PtN1C3 monatomic catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of nano material synthesis, and particularly relates to a PtN1C3 monatomic catalyst as well as a preparation method and application thereof. The monatomic catalyst comprises a carrier and a metal active component, the carrier is a nitrogen-doped multi-walled carbon nanotube, the metal active component is Pt, and Pt is dispersed on the carrier in an isolated monatomic form; pt is coordinated with three C and one N to form a PtN1C3 coordination configuration. The preparation method comprises the following steps: mixing a K2PtCl4 precursor with N-MWCNT (multi-walled carbon nanotubes) to react, so as to prepare K2PtCl4 / N-MWCNT; the K2PtCl4 / N-MWCNT and urea are mixed and ground, and the PtN1C3 is obtained through thermal annealing. The monatomic catalyst has the characteristics of high selectivity and high sensitivity, and is an ideal catalytic material for sensing hydrogen peroxide in the brain. The method provides support for construction of an electrochemical sensing platform for in-situ dynamic monitoring of H2O2 in the brain of a living body.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterial synthesis, and particularly relates to a PtN1C3 single-atom catalyst and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen peroxide (H2O2) as a key reactive oxygen species (ROS) plays a dual role in brain, both physiological signaling and pathological damage. Under physiological conditions, H2O2 is involved in the regulation of synaptic plasticity, neurotransmitter release and glial-neuron communication, which is essential for learning and memory. In pathological processes, abnormal accumulation of H2O2 triggers oxidative stress, directly leading to neuronal death, blood-brain barrier damage and neuroinflammatory cascade, which is the common pathological hub of Alzheimer's disease, Parkinson's disease, stroke and other diseases. Realizing the precise and specific in-situ dynamic monitoring of brain H2O2 and other neurochemical substances helps to reveal the physiological and pathological changes of the brain.

[0003] The electrochemical sensing platform based on implantable microelectrode provides an effective means for in vivo tracking of neurochemicals due to its excellent spatiotemporal resolution and mechanical adaptability. In the complex neurochemical monitoring environment in the living brain, the microelectrode needs to suppress non-target current interference, but the existing methods often reduce sensitivity as a trade-off. How to realize the synergistic optimization of high sensitivity and high selectivity of the sensing platform is still a major challenge. Single-atom catalysts (SACs) show breakthrough potential in the sensing field due to their maximum metal atom utilization, unique coordination and electronic structure. Most importantly, the result-oriented designability of SACs is expected to achieve high selectivity without sacrificing sensitivity. That is, by regulating the electronic cloud structure of SACs to shift the d-band center to the desired direction, the optimal adsorption strength of the target substance is achieved while other cross-reactions are eliminated. Current regulation methods such as defect site construction, axial ligand introduction and heteroatom doping all affect the electronic cloud configuration by introducing asymmetric factors to the periodic mirror structure. Notably, these systems with asymmetric factors often exhibit more excellent intrinsic activity and selectivity. Therefore, asymmetrically coordinated SACs developed based on symmetry breaking strategies will provide new ideas for developing implantable microelectrodes with both sensitivity and selectivity.

[0004] In the prior art, CN113786853B discloses a single-atom catalyst, a preparation method thereof, a microelectrode, a preparation method thereof and an application. The single-atom catalyst comprises graphite phase carbon nitride as a carrier, and copper single atoms loaded on the carrier as an active component; wherein the atomic percentage content of the active component in the single-atom catalyst is 0.07-0.2%; the graphite phase carbon nitride is mpg-C3N4. The single-atom catalyst has high selectivity for hydrogen peroxide and is not interfered by oxygen, but the sensitivity is unknown.

[0005] Therefore, it is of great significance to develop a single-atom catalyst with high selectivity and high sensitivity, and construct an implantable microelectrode for in-situ dynamic monitoring of target neurochemical substances in the brain of a living body, for studying the physiological and pathological processes of the brain. SUMMARY

[0006] Therefore, one of the purposes of the present application is to provide an asymmetrically coordinated single-atom catalyst. The single-atom catalyst has high selectivity and high sensitivity, and provides support for the construction of an electrochemical sensing platform for in-situ dynamic monitoring of H2O2 in the brain of a living body.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] An asymmetrically coordinated single-atom catalyst comprises a carrier and a metal active component;

[0009] The carrier is a nitrogen-doped multi-walled carbon nanotube;

[0010] The metal active component is Pt, and the metal active component is dispersed on the carrier in the form of isolated single atoms;

[0011] The Pt is coordinated with 3 carbon atoms and 1 nitrogen atom to form a PtN1C3 coordination configuration.

[0012] Further, the PtN1C3 single-atom catalyst contains single N atom doping, and the single N atom doping causes the electronic structure of the central metal atom to be asymmetric.

[0013] Further, the Pt loading in the asymmetrically coordinated single-atom catalyst is 0.5-2.0wt%, preferably 1.0-1.5wt%, and most preferably 1.26wt%.

[0014] Further, the d-band center of the central Pt atom of the asymmetrically coordinated PtN1C3 single-atom catalyst is -2.662eV.

[0015] The present application researches and finds that the result-oriented designability of SAC is expected to achieve high selectivity while not sacrificing sensitivity. That is, by regulating the electronic cloud structure of SAC through different strategies to make the d-band center shift in the desired direction, the optimal adsorption strength of the target substance is achieved while the occurrence of other cross reactions is eliminated. The current regulation means such as defect site construction, axial ligand introduction and heteroatom doping all affect the electronic cloud configuration by introducing asymmetric factors to the periodic mirror structure. Further research finds that these systems containing asymmetric factors often exhibit more excellent intrinsic activity and selectivity. Therefore, the asymmetrically coordinated engineering SAC developed based on the symmetry breaking strategy will provide a new idea for developing implantable microelectrodes with sensitivity and selectivity.

[0016] The present application further extends the theoretical advantage to the field of neurochemical sensing, and reports the atomic-level electronic structure reconstruction of the active site of Pt metal by a symmetry-breaking strategy to manufacture a PtN1C3 SAC with high sensitivity and high selectivity, and use it as a catalytic material for sensing hydrogen peroxide (H2O2) in the brain. The present application uses nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) fully immersed in K2PtCl4 solution as a precursor, and successfully prepares Pt-N-MWCNTs with an asymmetric N1C3 coordination and a typical N4 coordination in the first shell by adjusting the ratio of the dopant precursor and performing high-temperature annealing. Through theoretical calculation simulation, we found that the asymmetric electronic structure of the central metal atom caused by single N atom doping makes the d-band center of the Pt atom (-2.662eV) shift upward compared with PtN4 (-2.725eV), and is closer to the Fermi level, so that it is more active than other PtN x C 4-x The configuration of (x=0, 2-4) better balances the adsorption and desorption processes, thereby exhibiting a lower rate-determining step (RDS) energy barrier (0.173eV). In addition, in the reaction with common neurochemicals, the RDS energy barrier of each interferent is much higher than the 0.173eV of the RDS in the hydrogen peroxide reduction reaction (HPRR), which indicates that it is almost impossible for the interferents to react on the surface of PtN1C3 in thermodynamics. The present application develops a new type of microelectrode (PEDOT / PtN1C3 / CFE) based on PtN1C3, systematically evaluates its electrochemical performance in vitro, and verifies its application in actual complex environments. The results show that the microelectrode based on PtN1C3 can effectively monitor the in vivo H2O2 kinetic changes caused by resorcinol and rosmarinic acid. The PtN1C3 SAC provided by the present application provides support for in situ dynamic monitoring of neurochemicals in the brain.

[0017] The second object of the present application is to provide a preparation method of the asymmetric coordination single atom catalyst.

[0018] To achieve the above object, the present application adopts the following technical solutions:

[0019] The preparation method of the asymmetric coordination single atom catalyst comprises the following steps:

[0020] (1) mixing and reacting K2PtCl4 precursor and N-MWCNT to prepare K2PtCl4 / N-MWCNT;

[0021] (2) mixing and grinding the K2PtCl4 / N-MWCNT obtained in step (1) with urea, and obtaining PtN1C3 single atom catalyst by heat annealing;

[0022] The mass ratio of the K2PtCl4 / N-MWCNT to the urea is 1:3-6.

[0023] Further, the mass ratio of the K2PtCl4 precursor to the N-MWCNT is 1-2:1, preferably 9:8.

[0024] Further, the reaction condition of step (1) is magnetic stirring, and the rotation speed of the magnetic stirring is 1200-2000 rpm, and the time is 3-6 hours.

[0025] As preferred, the condition of the magnetic stirring is 1500 rpm vigorous stirring for 4 hours.

[0026] As preferred, after the solution obtained by the reaction of step (1) is rapidly frozen, vacuum freeze-drying is performed to obtain K2PtCl4 / N-MWCNT powder.

[0027] As more preferred, the freezing temperature is -70 to -90°C, more preferably -80°C.

[0028] As a preferred scheme, step (1) is specifically as follows:

[0029] 1) The K2PtCl4 precursor is dissolved in ultrapure water to prepare a Pt stock solution;

[0030] 2) The N-MWCNTs are dispersed in ultrapure water, and ultrasonic treatment is performed to fully disperse to obtain an N-MWCNT suspension;

[0031] 3) The Pt stock solution obtained in step 1) is added dropwise to the N-MWCNT suspension obtained in step 2), and Pt is loaded on the carbon tube by magnetic stirring; after rapid freezing, vacuum freeze-drying is performed to obtain K2PtCl4 / N-MWCNT powder.

[0032] As preferred, in step 1), the concentration of the Pt stock solution is 2-5 mg / mL, more preferably 3 mg / mL.

[0033] As preferred, in step 2), the ultrasonic treatment time is 20-60 minutes, more preferably 30 minutes.

[0034] As preferred, in step (2), the mass ratio of the K2PtCl4 / N-MWCNT to the urea is 1:4.

[0035] Further, in step (2), thermal annealing is performed under N2 atmosphere.

[0036] As preferred, the thermal annealing is performed in a tube furnace.

[0037] Further, in step (2), the thermal annealing comprises: heating to 700-1000℃ at a rate of 8-20℃ per minute, holding for 40-120 minutes, and then cooling to room temperature to obtain the PtN1C3 single-atom catalyst.

[0038] As preferred, in step (2), the thermal annealing comprises: heating to 750-850℃ at a rate of 8-15℃ per minute, holding for 50-70 minutes, and then cooling to room temperature to obtain the PtN1C3 single-atom catalyst.

[0039] As more preferred, in step (2), the thermal annealing comprises: heating to 800℃ at a rate of 10℃ per minute, holding for 1 hour, and then cooling to room temperature to obtain the PtN1C3 single-atom catalyst.

[0040] A third object of the present application is to provide an application of the aforementioned asymmetric coordination single-atom catalyst and / or the asymmetric coordination single-atom catalyst prepared by the aforementioned preparation method in the preparation of a microelectrode for monitoring the dynamic changes of H2O2 in the brain of a living body.

[0041] As preferred, the microelectrode is an implantable microelectrode.

[0042] The present application has the following beneficial effects:

[0043] 1. The present application reports a PtN1C3 single-atom catalyst prepared based on a symmetry-breaking strategy, which is applied to an implantable microelectrode sensing platform, which can not only monitor the small dynamic changes of the target substance hydrogen peroxide, but also shield the interference of common neurochemical substances. This is mainly due to the d-band center shift caused by high asymmetric coordination, which weakens the competitive adsorption of other neurochemical substances on the PtN1C3 single-atom catalyst, and makes it exhibit the lowest catalytic energy barrier (0.173 eV) to hydrogen peroxide. This endows the PtN1C3-based sensor with the ability to sensitively and specifically monitor the dynamic changes of hydrogen peroxide in the brain of a living rat induced by resorcinol and rosmarinic acid (the sensitivity can reach 692.1 μA·mM -1 ·cm -2 ). This study provides new insights for designing electrochemical sensing platforms using asymmetric coordination engineered single-atom catalysts.

[0044] 2. The asymmetric coordination PtN1C3 single-atom catalyst provided by the present application is an ideal HPRR catalyst, which has higher HPRR catalytic activity than other configurations such as PtN3C1, PtN2C2-1, PtN2C2-2, PtC4, and PtN4.

[0045] 3. The asymmetrically coordinated PtN1C3 monatomic catalyst provided by the application has the characteristics of high selectivity and high sensitivity to hydrogen peroxide. Data show that the amperometric response of the PtN1C3 monatomic catalyst to other neurochemical substances in the brain, such as ascorbic acid, dopamine, DOPAC, glucose, 5-hydroxytryptamine, and adrenaline, is extremely weak.

[0046] 4. The preparation method of the PtN1C3 monatomic catalyst provided by the application has the characteristics of simple operation, easy implementation, and suitability for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 are the synthesis and characterization experimental results of PtN1C3 and PtN4; wherein, Figure 1 -a is a synthesis flowchart of Pt-N-MWCNTs; Figure 1 -b is a TEM image of PtN1C3; Figure 1 -c is a HAADF-STEM image (10 nm) of PtN1C3; Figure 1 -d is a HAADF-STEM image (5 nm) of PtN1C3, and the Pt content measured by inductively coupled plasma mass spectrometry is inserted in the figure; Figure 1 -e is a HAADF-STEM image (2 nm) of PtN1C3, and the red circles in the figure represent the presence of single metal atoms; Figure 1 -f is a corresponding EDS element mapping image (stacked image) of PtN1C3; Figure 1 -g is a distribution image of C, N, O, and Pt elements in PtN1C3; Figure 1 -h is an EDS spectrum of N elements in PtN1C3; Figure 1 -i is an EDS spectrum of Pt elements in PtN1C3; Figure 1 -j is an XRD spectrum of PtN1C3, PtN4, and N-MWCNTs;

[0048] Figure 2 is a TEM image of PtN4;

[0049] Figure 3 is a ring-shaped dark-field scanning transmission electron microscope (AC HAADF STEM) image of PtN4, wherein the red circles represent the presence of single metal atoms;

[0050] Figure 4 is an EDS full spectrum of PtN1C3;

[0051] Figure 5 are the atomic structure analysis results of PtN1C3 and PtN4 by X-ray absorption spectroscopy; wherein, Figure 5-a is the XPS full spectrum of PtN1C3; Figure 5 -b is the N1s high-resolution XPS spectrum of PtN1C3; Figure 5 -c is the high-resolution XPS spectrum of Pt4f for PtN1C3; Figure 5 -d is the XPS full spectrum of PtN4; Figure 5 -e is the N1s high-resolution XPS spectrum of PtN4; Figure 5 -f represents the high-resolution XPS spectrum of Pt4f for PtN4; Figure 5 -g represents the Pt L3 edge X-ray absorption near-edge structure (XANES) spectrum of PtN1C3, Pt foil, and PtO2; Figure 5 -h represents the Fourier transform extended X-ray absorption fine structure (FT-EXAFS) spectra of PtN1C3, Pt foil, and PtO2; Figure 5 -i represents the EXAFS fitting curve of PtN1C3 in R space; Figure 5 -j represents the XANES spectra of PtN4, Pt foil, and PtO2 in PtL3; Figure 5 -k represents the EXAFS spectra of PtN4, Pt foil, and PtO2; Figure 5 -l is the EXAFS fitting curve of PtN4 in R space; Figure 5 -m represents the k of the Pt foil (PtN1C3 reference sample). 2 Wavelet transform (WT) plot of weighted EXAFS signal; Figure 5 -n is the k of PtO2 (PtN1C3 reference sample). 2 Wavelet transform diagram of weighted EXAFS signal; Figure 5 -o is the k of PtN1C3 2 Wavelet transform diagram of weighted EXAFS signal; Figure 5 -p represents the k of the Pt foil (PtN4 reference sample). 2 Wavelet transform diagram of weighted EXAFS signal; Figure 6 -q represents the k of PtO2 (PtN4 reference sample). 2 Wavelet transform diagram of weighted EXAFS signal; Figure 6 -r is the k of PtN4 2 Wavelet transform diagram of weighted EXAFS signal;

[0052] Figure 6 High-resolution XPS spectra of C1s and O1s of PtN1C3; among which, Figure 7 -a is the high-resolution XPS spectrum of PtN1C3's C1s; Figure 7 -b is the O1s high-resolution XPS spectrum of PtN1C3;

[0053] Figure 7High resolution XPS spectra of C1s and O1s for PtN4; wherein, Figure 8 - a is high resolution XPS spectra of C1s for PtN4; Figure 8 - b is high resolution XPS spectra of O1s for PtN4;

[0054] Figure 8 EXAFS spectra fitting plots of Pt foil (PtN1C3 reference sample) in k-space and R-space; wherein, Figure 9 - a is EXAFS spectra fitting plot of Pt foil (PtN1C3 reference sample) in k-space; Figure 9 - b is EXAFS spectra fitting plot of Pt foil (PtN1C3 reference sample) in R-space;

[0055] Figure 9 EXAFS spectra fitting plots of Pt foil (PtN4 reference sample) in k-space and R-space; wherein, Figure 10 - a is EXAFS spectra fitting plot of Pt foil (PtN4 reference sample) in k-space; Figure 11 - b is EXAFS spectra fitting plot of Pt foil (PtN4 reference sample) in R-space;

[0056] Figure 12 EXAFS fitting plot of PtN1C3 in k-space;

[0057] Figure 12 EXAFS fitting plot of PtN4 in k-space;

[0058] Figure 12 Amperometric responses of PtN1C3 / GCE and PtN4 / GCE upon continuous addition of 0.5 mM H2O2 and the corresponding fitted line plots; wherein, Figure 12 - a is amperometric responses of PtN1C3 / GCE and PtN4 / GCE upon continuous addition of 0.5 mM H2O2; Figure 13 - b is Figure 14 - a corresponding fitted line plots;

[0059] Figure 14 Optimized structures of H2O2 adsorbed on different PtN x C 4-x Calculated free energy diagram of HPRR in different configurations;

[0060] Figure 14 Optimized structures of H2O2 adsorbed on PtC4, PtN1C3, PtN2C2-1, PtN2C2-2, PtN3C1 and PtN4 and the calculated charge density difference of PtC4, PtN1C3, PtN2C2-1, PtN2C2-2, PtN3C1 and PtN4; wherein, Figure 14-a is the optimized structure diagram of H2O2 adsorbed on PtC4; Figure 14 -b is the optimized structure diagram of H2O2 adsorbed on PtN1C3; Figure 14 -c is the optimized structure diagram of H2O2 adsorbed on PtN2C2-1; Figure 14 -d is the optimized structure diagram of H2O2 adsorbed on PtN2C2-2; Figure 14 -e is the optimized structure diagram of H2O2 adsorbed on PtN3C1; Figure 14 -f is the optimized structure diagram of H2O2 adsorbed on PtN4; Figure 14 -g is the calculated charge density difference diagram of PtC4; Figure 14 -h is the calculated charge density difference diagram of PtN1C3; Figure 14 -i is the calculated charge density difference diagram of PtN2C2-1; Figure 14 -j is the calculated charge density difference diagram of PtN2C2-2; Figure 14 -k is the calculated charge density difference diagram of PtN3C1; Figure 15 -l is the calculated charge density difference diagram of PtN4;

[0061] Figure 15 are the band structure and the projected density of states (PDOS) of Pt d orbitals of different PtN x C 4-x configurations; wherein, Figure 15 -a is the band structure calculation result diagram of PtC4; Figure 15 -b is the Pt d orbital projected density of states calculation result diagram of PtC4; Figure 15 -c is the band structure calculation result diagram of PtN1C3; Figure 15 -d is the Pt d orbital projected density of states calculation result diagram of PtN1C3; Figure 15 -e is the band structure calculation result diagram of PtN2C2-1; Figure 15 -f is the Pt d orbital projected density of states calculation result diagram of PtN2C2-1; Figure 15 -g is the band structure calculation result diagram of PtN2C2-2; Figure 15 -h is the Pt d orbital projected density of states calculation result diagram of PtN2C2-2; Figure 15 -i is the band structure calculation result diagram of PtN3C1; Figure 15 -j is the Pt d orbital projected density of states calculation result diagram of PtN3C1; Figure 15 -k is the band structure calculation result diagram of PtN4; Figure 16 -l is the Pt d orbital projected density of states calculation result diagram of PtN4;

[0062] Figure 16The graph shows the selective experimental results for PtN1C3; where, Figure 16 -a is a schematic diagram of PtN1C3 selectivity; Figure 16 -b is the amperometric response curve of PtN1C3 / GCE in 0.1M PBS to 100μM H2O2, 3,4-dihydroxyphenylacetic acid, glucose, adrenaline, dopamine, uric acid, ascorbic acid, 5-hydroxytryptamine, and the addition of 100μM H2O2 again. Figure 16 -c is Figure 16 -b corresponding statistical bar chart (n=3); Figure 16 -d represents the free energy diagram of the reaction of H2O2 on PtN1C3, with the inset showing the corresponding catalytic mechanism schematic diagram; Figure 16 -e represents the free energy diagram of the reaction of AA on PtN1C3, where the inset is a schematic diagram of the corresponding catalytic mechanism; Figure 16 -f is the free energy diagram of the reaction of 5-HT on PtN1C3, where the inset is a schematic diagram of the corresponding catalytic mechanism; Figure 16 -g represents the free energy diagram of the reaction of DA on PtN1C3, with the inset showing the corresponding catalytic mechanism schematic diagram; Figure 16 -h is the free energy diagram of the reaction of Glu on PtN1C3, where the inset is a schematic diagram of the corresponding catalytic mechanism; Figure 16 -i represents the free energy diagram of the reaction of UA on PtN1C3, where the inset is a schematic diagram of the corresponding catalytic mechanism; Figure 16 -j is the Pt d orbital PDOS calculation result diagram when H2O2 reacts on PtN1C3; Figure 16 -k is the plot of the calculated projection density of states of the Pt d orbitals and Op orbitals when AA reacts on PtN1C3; Figure 16 -l is the calculated Pt d orbital projected density of states for the reaction of 5-HT on PtN1C3; Figure 16 -m is the plot of the calculated projection density of states of the Pt d orbitals and Op orbitals when DA reacts on PtN1C3; Figure 16 -n is the calculated density of states of the Ptd and Op orbitals of Glu during the reaction on PtN1C3; Figure 17 -o is the calculated Pt d orbital density of states for the reaction of UA on PtN1C3;

[0063] Figure 18 The graph shows the calculated Hamiltonian population (COHP) of the crystal orbitals of dopamine.

[0064] Figure 19 The graph shows the COHP calculation results of the Pt-O bond in the ascorbic acid reaction;

[0065] Figure 20 The graph shows the COHP calculation results for Pt-O bonds in the glucose reaction;

[0066] Figure 20 Figures related to the construction and electrochemical performance of PEDOT / PtN1C3 / CFE; wherein, Figure 20 -a is a schematic diagram of the preparation process of PEDOT / PtN1C3 / CFE; Figure 20 -b is a SEM image of bare CFE; Figure 20 -c is a SEM image of PEDOT / PtN1C3 / CFE; Figure 20 -d is the EIS diagram of bare CFE, PtN1C3 / CFE and PEDOT / PtN1C3 / CFE in 5 mM [Fe(CN)6] solution containing 0.1 M KCl; 3- / 4- Figure 20 -e is a graph of the response of PEDOT / PtN1C3 / CFE to different interferents; Figure 20 -f is the cyclic voltammetry (CV) curve of PEDOT / PtN1C3 / CFE at different scan rates (v) in 2 mM H2O2 solution; Figure 20 -g is Figure 20 -f corresponding current vs. scan rate graph; Figure 20 -h is a typical cyclic voltammetry curve of PEDOT / PtN1C3 / CFE in 0.1 M PBS solution (pH 7.40) with the addition of 0 mM, 2 mM and 4 mM H2O2, with a scan rate v = 100 mV / s; Figure 20 -i is the amperometric current response of PEDOT / PtN1C3 / CFE to the continuous addition of 5 mM to 100 mM (5, 10, 20, 50, 100 mM) H2O2; Figure 20 -k is the amperometric current response of PEDOT / PtN1C3 / CFE to the continuous addition of 200 mM to 5 mM (0.2, 0.5, 1, 2, 5 mM) H2O2; Figure 20 -l is an image of PEDOT / PtN1C3 / CFE before bending; Figure 20 -m is an image of PEDOT / PtN1C3 / CFE after the 50th bending; Figure 20 -n is the CV curve of PEDOT / PtN1C3 / CFE at different bending times in 0.1 M PBS solution (pH 7.40) containing 4 mM H2O2; Figure 20 -o is the amperometric current response of PEDOT / PtN1C3 / CFE and bare CFE to 1 mM H2O2, I0 and I represent the current values at the initial time and the specified time, respectively; Figure 20 -p is Figure 20 -o corresponding statistical bar graph (n = 3); Figure 20 ​q is a plot of cell viability of PC12 cells incubated with PEDOT / PtN1C3 / CFE or bare CFE for 24 hours (n=3); Figure 20 r is bright field and fluorescence images of PC12 cells stained with calcein-AM (green) and propidium iodide (PI, red); Figure 20 s is fluorescence microscopy images of PEDOT / PtN1C3 / CFE and bare CFE treated with 5 mg / ml FITC-BSA; Figure 20 t is a plot of contact angle measurements of bare CC (n=3); Figure 20 u is a plot of contact angle measurements of PEDOT / PtN1C3 / CC (n=3); Figure 20 v is a plot of amperometric response of PEDOT / PtN1C3 / CFE and bare CFE to 1 mM H2O2 in 0.1 M PBS solution (pH 7.40) containing 10 mg / ml BSA at -0.3 V vs. Ag / AgCl potential (n=3); Figure 20 w is Figure 20 v is the corresponding statistical bar graph (n=3);

[0067] Figure 20 is a plot of cyclic voltammograms of bare CFE, PtN1C3 / CFE and PEDOT / PtN1C3 / CFE in 0.1 M PBS solution (pH 7.40) without H2O2;

[0068] Figure 20 is a plot of amperometric current curves of PEDOT / PtN1C3 / CFE at different potentials upon continuous addition of 1 mM H2O2 in stirred 0.1 M PBS (pH=7.40) and the corresponding statistical results plot; wherein, Figure 21 a is a plot of amperometric current curves; Figure 22 b is Figure 22 a statistical results plot of a;

[0069] Figure 22 is a plot of amperometric response curves of PEDOT / PtN1C3 / CFE to 100 mM H2O2, DOPAC, Glu, E, DA, UA, AA, 5-HT and 100 mM H2O2 added again in 0.1 M PBS and the corresponding statistical bar graph (n=3); wherein, Figure 22 a is a plot of amperometric response curves; Figure 23 b is Figure 23 a corresponding statistical bar graph (n=3) of a;

[0070] Figure 23Differential pulse voltammetry (DPV) plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM H2O2, 1 mM 5-HT, 1 mM AA, 1 mM DA, 1 mM DOPAC, 1 mM E, 1 mM Glu and 1 mM UA; wherein, Figure 23 -a is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM H2O2; Figure 24 -b is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM 5-HT; Figure 24 -c is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM AA; Figure 24 -d is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM DA; Figure 24 -e is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM DOPAC; Figure 24 -f is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM E; Figure 24 -g is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM Glu; Figure 24 -h is the DPV plot of PEDOT / PtN1C3 / CFE in PBS containing 1 mM UA;

[0071] Figure 24 Cyclic voltammogram of bare CFE, PtN1C3 / CFE and PEDOT / PtN1C3 / CFE in 0.1 M PBS solution (pH 7.40) containing 2 mM H2O2;

[0072] Figure 24 Typical amperometric current response of PEDOT / PtN1C3 / CFE in PBS with successive additions of H2O2 (500 μM each addition) before and after 2 hours of immersion in cell culture medium and plot of pre- and post-calibration curves obtained under this condition; wherein, Figure 25 -a is the plot of typical amperometric current response; Figure 26 -b is the plot of pre- (blue) and post- (purple) calibration curves obtained under condition Figure 26 -a;

[0073] Figure 26 H2O2 sensing related experimental results of PEDOT / PtN1C3 / CFE in PBS solution containing PC12 cells and in vivo; wherein, Figure 27-a is the H2O2 release current response graph recorded by PEDOT / PtN1C3 / CFE when PBS (NC), 100 mM resorcinol (Res), 500 U catalase (CAT) + 100 mM Res, 100 μM rosmarinic acid (RA) + 100 mM Res are added to the PBS solution containing PC12 cells; Figure 27 -b is Figure 27 -a is the corresponding H2O2 release amount statistical result graph (n = 3); Figure 27 -c is the fluorescence imaging graph of the reactive oxygen species (ROS) level in PC12 cells under different treatment conditions; Figure 27 -d is the quantitative analysis result graph of the ROS production amount (n = 3); Figure 27 -e is a schematic diagram of PEDOT / PtN1C3 / CFE for in vivo H2O2 monitoring; Figure 27 -f is a graph of the catalytic mechanism of HPRR on PtN1C3; Figure 27 -g is the H2O2 release current response graph recorded by PEDOT / PtN1C3 / CFE when PBS (NC), 100 mM Res, 500 U CAT + 100 mM Res, 100 μM RA + 100 mM Res are locally microinjected (200 nL·s -1 , for 5 seconds) into the cerebral cortex; Figure 27 -h is Figure 28 -g is the corresponding H2O2 release amount statistical result graph (n = 3); the data points represent the average value of multiple samples, and all error lines are standard deviations; statistical analysis uses one-way ANOVA (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001);

[0074] Figure 28 is the pre-calibration curve and linear relationship graph for in vivo H2O2 detection; wherein, Figure 28 -a is the amperometric current response graph of PEDOT / PtN1C3 / CFE when 500 μM H2O2 is continuously added to PBS (pH 7.4); Figure 1 -b is the functional relationship graph of current intensity and H2O2 concentration. DETAILED DESCRIPTION

[0075] The technical solutions of the present application will be described further clearly and completely in combination with specific examples. Obviously, the described examples are only some of the examples of the present application, but not all. Therefore, all other examples obtained by those skilled in the art based on the examples in the present application without creative labor are within the protection scope of the present application.

[0076] The reagents involved in the present application, such as no special instructions, can be purchased through the conventional market channels. For example, in the embodiments of the present application, nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) are purchased from Nanjing Xianfeng Nanometer Material Technology Co., Ltd. of China; 3,4-ethylenedioxythiophene (EDOT) is purchased from Cool Chemical Technology Co., Ltd. of Beijing, China; tetrabutylammonium tetrafluoroborate (TFB) and rosmarinic acid (RA) are purchased from Aladdin Biochemical Technology Co., Ltd. of Shanghai, China; hydrogen peroxide (AR, 30wt%), acetone, nitric acid, urea and potassium hydroxide are purchased from Chongqing Chuandong Chemical Industry Group Co., Ltd. of China; potassium tetrachloroplatinate (K2PtCl4), resorcinol (Res), dopamine (DA), uric acid (UA), ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC), epinephrine (E), 5-hydroxytryptamine (5-HT) are purchased from Alfa Aesar (Titan Science and Technology Co., Ltd. of Shanghai, China); glucose (Glu) is purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd.; acetonitrile is purchased from Chengdu chron Chemical Co., Ltd. of China; phosphate buffered solution (PBS) is prepared by mixing 0.1M Na2HPO4·12H2O and 0.1M NaH2PO4·2H2O at a ratio of 81:19, and the pH is adjusted to 7.40 by 0.1M Na2HPO4·12H2O or 0.1M NaH2PO4·2H2O using a pH meter; potassium ferrocyanide trihydrate (K4[Fe(CN)6]) and potassium ferricyanide (K3[Fe(CN)6]) are purchased from Shanghai Aladdin Reagent Co., Ltd.; potassium ferricyanide solution ([Fe(CN)6] 3- / 4- ) is prepared with PBS containing 5mM K3[Fe(CN)6], 5mM K4[Fe(CN)6] and 0.1M KCl; CCK-8 and calcein / propidium iodide cell viability / cytotoxicity detection kit are purchased from Biyun Tian Biotechnology Co., Ltd.; RPMI1640 basic medium is purchased from Gibco; fetal bovine serum (FBS) is provided by Lonsera; ultrapure water (18.2MΩ) used in the experiment is prepared by an ultrapure water system (AOSIDE INSTRUMENT); freeze-dried catalase (A001847-0002) is purchased from Shanghai Sangon Biological Engineering Co., Ltd.

[0077] In the embodiments of the present application, the scanning electron microscope (SEM) images of the morphology of the modified carbon fiber electrode (CFE) are taken by a field emission gun Hitachi S-8010 scanning electron microscope (Tokyo, Japan, Hitachi). The transmission electron microscope (TEM) images are recorded on a JEM-2100F (Japan Electron Instruments) operating at 200 kV. The X-ray diffraction (XRD) patterns of Pt-N-MWCNTs are obtained by an X-ray diffractometer (XRD-6100, Shimadzu). The X-ray photoelectron spectroscopy (XPS) measurements are performed using a photoelectron spectrometer (K-Alpha, Thermo Fisher Scientific), radiation source: Al Kα source, test energy: 1486.8 eV, test spot area: 400 μm, test tube voltage: 15 kV, tube current: 10 mA, analysis chamber background vacuum: 2 × 10 -9 mbar, Ar ion etching can be performed, energy 2000 V, depth generally 3-5 nm. Inductively coupled plasma mass spectrometry (ICP-MS) is measured on an Agilent 7800 inductively coupled plasma mass spectrometer. Dark field scanning transmission electron microscopy (STEM) characterization is performed using FEI-Themis Z (FEI / Thermo Fisher Scientific, USA) at 200 kV. X-ray absorption spectroscopy (XAS) at Pt K edge (7709 eV), including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), is collected at the central beamline of the Singapore Synchrotron Light Source (SSLS), where the monochromator uses a pair of channel-cut Si(111) crystals. Pt K-edge XANES data are recorded in transmission mode. Pt foil and PtO2 are used as references. The storage ring operates at an energy of 2.5 GeV with an average electron current below 200 mA. The EXAFS data collected are extracted and processed according to standard procedures using the ATHENA module in the FEFIT software package. By applying a Bessel window function, k x(k) is obtained in the range of 1 3 The weighted Fourier transform (FT) results in R space.

[0078] In the embodiments of the present application, the electrochemical measurement method is as follows:

[0079] All electrochemical measurements are performed using an electrochemical workstation (CHI 660E, Shanghai, China). Glassy carbon electrodes (GCE) are cleaned by physical polishing and chemical cleaning, and then immersed in a 0.01 M Fe(CN)6 3- / Fe(CN)6 4-The reversible electrode reaction was checked. Then, for sensitivity measurement, 4 μΐ of 10 mg / mL of PtN1C3 or PtN4 was dropped onto a clean GCE and dried at room temperature. For selectivity measurement, 8 μΐ of 10 mg / mL of PtN1C3 or PtN4 was dropped and dried. A classic three-electrode system was constructed with a Pt wire as CE, Ag / AgCl as RE, and PtN1C3 / GCE, PtN4 / GCE or PEDOT / PtN1C3 / CFE as WE. The modified electrodes were characterized by EIS in 5 mM potassium ferricyanide solution containing 0.1 M KCl. The EIS spectra frequency range was 1000000 Hz to 0.08 Hz. i-t, CV, DPV were performed in 0.1 M PBS solution (pH = 7.40). The optimal working voltage was -0.3 V. The CV characterization conditions were: potential range -1.0 V to 1.0 V, scan rate 100 mV / s. The DPV voltage range was -1.0 V to 1.0 V, pulse amplitude 50 mV, pulse period 0.5 s.

[0080] In the embodiments of the present application, the cytotoxicity quantitative test method is as follows:

[0081] PC12 cells (rat pheochromocytoma cells) were purchased from Shanghai Aicell Bioscience Co., Ltd. The PC12 cells were cultured in 1640 medium containing 10% FBS and 1% penicillin-streptomycin (5% CO2, 37°C). The CCs with the same modification were cut into appropriate sizes and sterilized under ultraviolet (UV) light. After the PC12 cells were resuspended after digestion, they were inoculated in a 96-well plate and cultured for 24 hours. Then, small pieces of CC were added to the wells. After 24 hours of incubation, the culture medium was removed, fresh culture medium (100 μΐ) containing CCK-8 (10 μΐ) was added to each well, and incubated for 2 hours. When the solution color changed to orange, the absorbance at 450 nm was recorded. The relative cell viability was calculated according to the following formula: (ODtest / ODControl) x 100%.

[0082] In the embodiments of the present application, the fluorescent staining and cell imaging method is as follows:

[0083] PC12 cells were cultured on the same modified CC (1 cm x 1 cm) to evaluate the biocompatibility of the electrode. After a period of cell inoculation, the culture medium was aspirated, washed once with PBS, and then the cells growing on the CC were stained with the fluorescent live / dead cell dyes calcein acetyl oxymethyl (AM) and propidium iodide (PI). Finally, the stained cells were incubated in a cell incubator at 37°C for 30 minutes before being observed and imaged using a fluorescence microscope.

[0084] In the embodiments of the present application, the intracellular reactive oxygen species level method is as follows:

[0085] To verify the amount of reactive oxygen species produced by cells induced by different treatment conditions, PC12 cells were seeded in culture dishes and incubated at 37°C, 5% CO2 and humidified environment for 24 hours, incubated with DCFH-DA (Beyotime Biotechnology) for 30 minutes at 37°C, then added with a fresh prepared Res solution with a final concentration of 100 μM, a fresh Res solution containing 100 μM RA, and acted for 10 minutes. Imaging observation and analysis were performed using an inverted fluorescence microscope (ECLIPSE Ti2, Nikon).

[0086] In the embodiments of the present application, the density functional theory calculation method is as follows:

[0087] The density functional theory (DFT) calculation is performed using the Vienna ab initio simulation package (VASP). The interaction between core electrons and valence electrons is determined by the projected augmented wave (PAW) pseudo-potential. The exchange correlation functional adopts the Perdew-Burke-Ernzerhof (PBE) functional under the generalized gradient approximation. The DFT-D3 method with Grimme semi-empirical dispersion correction is used to calculate the van der Waals interaction.

[0088] The cutoff energy of the plane wave basis set is set to 450 eV. During the structure optimization process, a (3x2x1) k-point grid generated by the Gamma scheme is used to sample the Brillouin zone. The total energy convergence threshold of the ground state electron density is set to 10 -5 eV, and the structure optimization is considered to be converged when the maximum force on any ion is less than A vacuum layer of about is set in the z direction to avoid the interaction between the periodic substrate and its repeated images. For N-doped systems, a (4x4x1) graphene supercell is used, in which a Pt atom is embedded in a double vacancy site (denoted as PtNX). Molecular calculations are performed in a (15x15x15) box, k-point sampling is performed using the Gamma grid scheme, and the cutoff energy is 450 eV.

[0089] The HPRR pathway includes the following steps:

[0090] H2O2+*→H2O2*

[0091] H2O2*→2OH*

[0092] 2OH*+H + +e - →H2O+OH*

[0093] OH*+H + +e - →H2O+*

[0094] Under standard conditions (298 K, PH2 = 1 bar, Ph = 0), the chemical potential of (H + +e - ) (i.e. the free energy of each H) is equal to the chemical potential of 1 / 2 H2 when the reference potential is set to the potential of the standard hydrogen electrode. The change in free energy of the reaction (Delta G) is further estimated by the following function:

[0095] Delta G = Delta H - T Delta S - q U + kBTln10 x pH

[0096] Where Delta H: the reaction enthalpy of each elementary step, calculated by using the zero-point energy (ZPE) corrected reaction energy (Delta E); Delta S: the entropy change at temperature T; U: the applied potential; q: the charge transferred in each elementary step; kB: the Boltzmann constant.

[0097] We use vesta to build a series of surface structure models of PtNXC4-X (X = 0-4). The influence of different N atom coordination numbers on the HPRR of single-atom catalysts with Pt as the active site is studied. The reason why the PtN1C3 configuration has high electrocatalytic activity for HPRR compared with the typical PtN4 configuration is theoretically explained from multiple aspects such as thermodynamics and electronic structure. Finally, we continue to build other small molecule adsorption and catalysis models to theoretically explain the selectivity of PtN1C3 to H2O2.

[0098] In the embodiment of the application, the in situ detection method of cell-secreted H2O2 is as follows:

[0099] PC12 cells are purchased from Shanghai Aicell Biotechnology Co., Ltd. They are cultured in 1640 medium containing 10% FBS and 1% penicillin-streptomycin under 5% CO2 and 37 DEG C. The cells are inoculated in a cell culture dish for 24 hours, and the amperometric current response is measured at the optimal applied potential (-0.3 V) using the sterile PEDOT / PtN1C3 / CFE obtained after ultraviolet irradiation. During the measurement, after the signal is stable, 100 muM Res, 100 muM Res+100 muM RA and 100 muM Res+500 uCAT are used as stimulants to detect the H2O2 released by the cells.

[0100] In the embodiment of the application, the in vivo experiment is as follows:

[0101] Adult male SD rats (300-350 g) were anesthetized with isoflurane (4% induction, 2% maintenance) by a gas pump R520 (RWD Life Science Co., Ltd., Shenzhen, China) and fixed on a stereotaxic frame for craniotomy surgery. PEDOT / PtN1C3 / CFE was inserted into the right cortex (AP = 3 mm, L = 2 mm lateral to the bregma, V = 1 mm from the skull surface) according to the stereotaxic procedure. A prepared micron Ag / AgCl (saturated KCl) reference electrode and a platinum wire counter electrode were placed intradurally. Exogenous PBS containing 100 mmol Res, 100 μmol RA or 500 U / mL C AT was microinjected into the local area of the microelectrode in the brain through a quartz capillary (length 4 cm, inner diameter 50 μm, outer diameter 375 μm) implanted in the right cortex in parallel with PEDOT / PtN1C3 / CFE, which is also called a single-atom catalyst-based microsensor. These solutions were pumped from a gas-impermeable syringe by a microsyringe pump R480 (RWD Life Science Co., Ltd., Shenzhen, China). All local microinjections were performed at a rate of 200 nl s -1 The local microinjection volume of Res was 1000 nL. In the inhibitor treatment, 2000 nL of RA and CAT were injected, respectively, before the injection of Res, and incubated for 15 min and 1 min. PEDOT / PtN1C3 / CFE was polarized at -0.3 V for amperometric measurement of H2O2 in the rat cerebral cortex.

[0102] In the embodiments of the present application, the statistical analysis method is as follows:

[0103] Statistical analysis was performed using Excel and GraphPad Prism 9. The sample size for each statistical analysis was greater than or equal to 3 (n≥3). Statistical comparisons between two groups used two-tailed t-tests and one-way ANOVA. Significance was represented as *p≤0.05, **p≤0.01, ***p≤0.001, ****p≤0.0001. n.s. represents no statistically significant difference.

[0104] In the embodiments of the present application, carbon fiber electrodes (CFEs, diameter 7 μm) were prepared as follows:

[0105] Glass capillary tubes (inner diameter 1.5 mm, length 100 mm) were drawn into two tapered glass-coated carbon fiber tip electrodes using a micropipette puller (MP-500, RWD, Shenzhen, China), and the thin tips of each tip were broken to a diameter of 10-15 pm. The drawn capillary tubes were used as sheaths for the CFEs. Carbon fibers (diameter 7 pm, Tony Electronic Co. Ltd, Shenzhen, China) were then sequentially sonicated in acetone, 3 M HNO3, 1 M KOH, and ultrapure water (18.2 MW) for 5 min each. They were then dried in a vacuum oven at 60 °C for 6 h. Individual carbon fibers on a clean glass plate were attached to a copper wire (diameter 200 pm) that was slightly longer than the glass capillary tube using silver conductive glue and left at 80 °C for 1 h. Then, the CFEs were made by carefully inserting the carbon fiber with the copper wire into the capillary tube such that the carbon fiber was exposed to the thin open end of the capillary tube and the copper wire was exposed to the other end of the capillary tube. Next, the end of the glass capillary tube was vertically dipped into a pool of molten paraffin wax, taking care that the paraffin wax did not touch the carbon fiber of the tip, and then it was left in room temperature air for the paraffin wax to solidify. Finally, the exposed CFEs were cut to about 200-250 pm using a surgical blade under a microscope.

[0106] Example 1. Preparation of PtN1C3 and PtN4

[0107] (1) Preparation of K2PtCl4 / N-MWCNT: K2PtCl4precursor was dissolved in ultrapure water to form a stock solution of 3 mg / mL. 0.16 g of N-MWCNTs were dispersed in 100 mL of ultrapure water and sonicated for 30 min to fully disperse and form a suspension. 600 pL of the Pt stock solution was added dropwise to the N-MWCNT suspension, which was vigorously stirred on a magnetic stirrer at maximum speed of 1500 rpm for 4 h to load Pt on the carbon tubes. It was quickly frozen in a -80 °C freezer and then transferred to a vacuum freeze-dryer until a black powder of K2PtCl4 / N-MWCNT was obtained.

[0108] (2) Preparation of PtN1C3: The K2PtCl4 / N-MWCNT powder prepared in step (1) was ground with urea at a mass ratio of 1 :4, and then heated to 800 °C at a rate of 10 °C per minute under N2flow in a tube furnace and kept at 800 °C for 1 h before cooling to room temperature to obtain PtN1C3.

[0109] (3) Preparation of PtN4: The K2PtCl4 / N-MWCNT powder prepared in step (1) was ground with urea at a mass ratio of 1 :10, and then heated to 800 °C at a rate of 10 °C per minute under N2flow in a tube furnace and kept at 800 °C for 1 h before cooling to room temperature to obtain PtN4.

[0110] Example 2. Characterization of PtN1C3 and PtN4

[0111] Pt monolayers were anchored on N-MWCNTs to synthesize materials with large surface area and good electrical conductivity. As shown in Figure 1 -a, the synthesis of Pt-N-MWCNTs with different coordination environments included several steps. Briefly, a small amount of Pt cations was first dispersed in ultrapure water containing N-MWCNTs under vigorous stirring, followed by freeze-drying and thermal annealing with specific dopant precursors in different proportions. No metal clusters or nanoparticles were observed in the PtN1C3 bright-field transmission electron microscopy (TEM) images with a constant Pt loading of 1.26 wt%, as shown in Figure 2 -b. We also observed the same results in the TEM images of PtN4, as shown in Figure 1 . Figure 1 -c Figure 3 -e shows the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) characterization of PtN1C3, which still retains the structure of N-MWCNTs with clear edges of the multi-layered rolled graphene layers, while isolated Pt monolayers are identified as bright spots due to their higher Z-contrast compared to the adjacent C / N sites. Similarly, Figure 1 Pt in PtN4 is also atomically dispersed. Figure 1 -d, the Pt content of PtN1C3 was measured to be 1.26 wt% by inductively coupled plasma mass spectrometry (ICP-MS). Figure 1 -f and Figure 1 -g show that the carbon (C), nitrogen (N), and platinum (Pt) elements are uniformly distributed throughout the structure by energy dispersive X-ray spectroscopy (EDS) mapping images. In addition, Figure 1 -h, Figure 4 -i, and Figure 1 EDS spectra clearly show the characteristic peaks of Pt and N elements, which suggests the possible formation of Pt-N X species. Figure 5 -j shows the high-resolution X-ray diffraction (XRD) patterns, which indicate that there is no long-range ordered Pt crystal structure or nanoparticles in PtN1C3 and PtN4.

[0112] The composition and related Pt valence states of PtN1C3 and PtN4 were further investigated by in situ X-ray photoelectron spectroscopy (XPS), as shown in Figure 5 -a and Figure 5- d. The XPS spectra depict the compositional information, where a Pt content of about 0.15 at% was observed on the sample. The XPS spectra of the Pt N1C3, N 1s region is shown in Figure 5 - b, after core level decomposition, three different coordination structures were identified, namely pyridinic nitrogen (398.5 eV), graphitic nitrogen (401.2 eV) and Pt-N (399.9 eV). In addition, pyrrolic nitrogen (400.6 eV) can also be observed in the N 1s region of PtN4, which can be attributed to the introduction of a higher precursor ratio, see Figure 5 - e. Figure 5 - c, the core level XPS spectra of the Pt 4f region is plotted, where the Pt 4f 7 / 2 binding energy is 72.1 eV. Notably, this value is higher than metallic platinum (71.2 eV), indicating a partial charge transfer from the Pt central atom to the adjacent metallic impurity dopant. This can also be observed in the Pt 4f region of PtN4, see Figure 6 - f. More information on the C 1s and O 1s can be found in Figure 7 and Figure 5 In addition, we also utilized Pt L3-edge XAS spectroscopy to reveal the chemical state and coordination environment of PtN1C3 and PtN4 at the atomic level. The partial depletion of free electrons in the Pt valence band is further confirmed by the X-ray near-edge absorption structure (XANES) spectra shown in Figure 5 - d and Figure 5 - g, where the white line intensity of the prepared catalysts is higher than that of platinum foil, indicating the presence of slightly positively charged Pt δ+ species stabilized on the N-MWCNTs support. Furthermore, Figure 5 - e and Figure 8 - h show the Fourier-transform extended X-ray absorption fine structure spectroscopy (FT-EXAFS). Pt foil exhibits a typical first shell Pt-Pt pairing at about , see Figure 9 and Figure 5 ; while the Pt-O interaction is located at about , which is not observed in both prepared catalysts. For PtN1C3 and PtN4, the main R-space features are about and , which can be caused by the characteristic bonding of Pt-N and the different coordination numbers. To further explore the Pt atomic distribution in PtN1C3, we performed a wavelet transform (WT) analysis of the Pt L3-edge EXAFS. As shown in Figure 5 - j ~ Figure 5 - 1, only one Pt-N coordination related feature is observed from the WT spectrum of PtN1C3 at about The maximum intensity at this location differs from the WT spectrum of the Pt foil, which is at... There is a maximum intensity value corresponding to the Pt-Pt contribution, indicating that there are no Pt-Pt bonds in PtN1C3, but rather isolated Pt atoms. Similarly, only one maximum intensity value related to Pt-N coordination was observed in the WT of PtN4, see [link to WT]. Figure 5 -m~ Figure 5 -r. Based on the fitted curves obtained in k and R spaces ( Figure 5 -f、 Figure 10 -i、 Figure 11 and Figure 12 Based on Tables 1 and 2, the quantitative structural parameters of Pt in PtN1C3 and PtN4 were obtained using least-squares EXAFS fitting. Analysis showed that the coordination numbers of PtN1C3 and PtN4 are approximately 1 (PtN1C3) and 4 (PtN4), respectively, and the average bond lengths of Pt-N are... (PtN1C3) and (PtN4). However, since the precursor used was chloride, some Cl was not completely removed, resulting in some Pt-Cl coordination, which is normal. In PtN1C3, the second shell of Pt coordinates with C in CN, with an N bridge. In summary, given the similar manufacturing methods and processing procedures of the two samples, we believe that reducing the introduced urea ratio before thermal annealing directly contributed to the reduction of N doping content, disrupting the symmetric structure of PtN4, thus obtaining PtN1C3 with an asymmetric coordination structure.

[0113] Table 1. Pt L3 edge EXAFS fitting parameters (S0) 2 =0.89)

[0114]

[0115] In Table 1, CN represents the coordination number; R represents the bond length; and σ represents the σ value. 2 Debye-Waller factor; ΔE: internal potential correction; R factor: goodness of fit. *Fit with fixed parameters.

[0116] Table 2. EXAFS Fitting Parameters for Pt L3 Edge (S0) 2 =0.70 (from Pt foil)

[0117]

[0118] In Table 2, CN represents the coordination number; R represents the bond length; and σ represents the scalar distance. 2 Debye-Waller factor; ΔE: internal potential correction; R factor: goodness of fit.

[0119] Example 3. Electrocatalytic performance of PtN1C3

[0120] First, the electrocatalytic performance of PtN1C3 and PtN4 in phosphate buffered saline (PBS) for HPRR was investigated by amperometric method (it). Figure 13 As shown, with the continuous addition of H2O2, the current signals of both PtN1C3 / GCE and PtN4 / GCE exhibited a stepwise response, while the reduction current signal of PtN1C3 / GCE was significantly greater than that of PtN4 / GCE, with a sensitivity increase of approximately 4.9 times. This indicates that the electrocatalytic performance of asymmetrically coordinated PtN1C3 is significantly improved compared to that of classically symmetrically coordinated PtN4. To further explore the reasons for the high HPRR electrocatalytic activity of PtN1C3, we used DFT calculations to investigate the different configurations of Pt-N, including PtN1C3 and PtN4. x -C 4-x (x = 0–4) Catalytic mechanism of HPRR (see SI for more calculation details). We constructed Pt-N with different configurations. x -C 4-x The calculation model at -0.3V, i.e., PtC4, PtN1C3, PtN2C2-1 (cis configuration, two N atoms on the same side), PtN2C2-2 (trans configuration, two N atoms on opposite sides), PtN3C1, and PtN4 with different C and N positions, is presented. The Gibbs free energy (ΔG) and adsorption structure for each basic step are also described. Figure 14 , Figure 14 -a~ Figure 13 As shown in -f, the basic reactions of the HPRR reaction include the adsorption of H2O2 molecules, the homolytic cleavage of H2O2 into two hydroxyl groups adsorbed on Pt atoms, and two proton transfers that cause the adsorbed hydroxyl groups to generate water. Figure 14 The free energy diagram of HPRR shown indicates that Pt-N x -C 4-x The rate-determining step for the reaction (x=0-3) is the adsorption of H2O2, while for PtN4 the rate-determining step is the homolytic cleavage of H2O2. The reactivity decreases in the order of PtN1C3 > PtN3C1 > PtN2C2-1 > PtN2C2-2 > PtC4 > PtN4. This means that among all C and N atom coordination configurations, PtN1C3 exhibits the lowest reaction energy barrier (0.173 eV) for HPRR, making it the optimal N-doped coordination configuration for HPRR catalysis. Therefore, PtN1C3 is one of the most ideal HPRR catalyst choices. This is likely attributed to the asymmetry of the central metal atom's electronic structure caused by single N atom doping, which can be explained by… Figure 14 -g~ Figure 15The differential charge plots shown in FIG. 1 intuitively indicate that this will lead to a shift of the d-band center of Pt atom. Sabatier principle states that for a good catalyst with a well-defined active site structure, the adsorbed atom or molecule should be bound with moderate strength, neither too weak to activate the reactants nor too strong to prevent product desorption. The d-band center theory suggests that the adsorption strength of transition metal surface catalytic reactions is closely related to the d-band center position of the active metal center. By judging the adsorption strength through the d-band center of the central Pt atom, we can provide a conceptual framework for exploring the best catalyst. To this end, we calculated the band structure of different coordination systems and focused on the contribution of the d-orbital PDOS of transition metal Pt to the total DOS and the value of its d-band center, as shown in Figure 16 PtC4(-3.426eV)<PtN3C1(-2.769eV)<PtN4(-2.725eV)<PtN1C3(-2.662eV)<PtN2C2-2(-2.505eV)<PtN2C2-1(-2.244eV). The d-band center of the central Pt atom of PtN1C3(-2.662eV) is slightly shifted upwards compared to that of PtN4(-2.725eV) and is closer to the Fermi level, which makes it better balance the adsorption-desorption process. In addition, among the other configurations calculated, PtC4 and PtN3C1 have obvious deviation of d-band center and have difficulty in adsorption, and although PtN2C2-1 and PtN2C2-2 have a d-band center closer to the Fermi level, they may have a higher adsorption energy of H2O2 due to the lower DOS near the Fermi level. In summary, the symmetry-broken PtN1C3 is more suitable for the best adsorption-desorption position than other Pt-N x -C 4-x (x = 0, 2, 3, 4) is closer to the best adsorption-desorption position, which theoretically explains the high HPRR catalytic activity of PtN1C3.

[0121] Example 4. Selectivity of PtN1C3

[0122] Example 3 explains the high HPRR electrocatalytic activity of PtN1C3 prepared by symmetry-breaking strategy and its possible mechanism. This example further explores its high selectivity for H2O2, as shown in Figure 16 -a. To this end, we again directly modify PtN1C3 on a glassy carbon electrode (GCE), and measure its response to other neurochemicals in the brain, AA (ascorbic acid), DA (dopamine), DOPAC (3,4-dihydroxyphenylacetic acid), Glucose (glucose), 5-HT (5-hydroxytryptamine), E (epinephrine), and H2O2 of the same concentration by i-t method, and the results are shown in Figure 16 -b ~ Figure 16compared to H2O2. The above experimental results show that PtN1C3 only produces a significant response to H2O2, and does not produce a response to other neurochemicals in the brain, proving its high selectivity to H2O2. In order to further explore the possible mechanism of PtN1C3 having high selectivity to H2O2, we performed DFT simulation calculations to study the possible reaction mechanism of some interfering substances on PtN1C3 when the applied potential is -0.3 V, and further explored the thermodynamic possibility of the redox reaction of these substances on PtN1C3. As shown in Figure 16 -d and Figure 16 -j, when H2O2 is reduced, only the first step of H2O2 adsorption is an endothermic reaction, which is the rate-determining step (RDS), and ΔG = 0.173 eV. The d-orbital projected density of state of Pt atom has a relatively rich electronic state on the side of the Fermi level, indicating that the Pt atom has a relatively active d-orbital valence electron, which may be one of the reasons why Pt-N1C3 can effectively adsorb H2O2 molecules. The adsorbed H2O2 spontaneously homolytic into two OH* and adsorbed on the Pt atom, this step does not involve electron transfer, and the reaction intermediate at this time is in a relatively high-energy unstable state, followed by the two-step OH* desorption involving a proton transfer step. PtN1C3 has good adsorption capacity for hydroxyl groups, which can not only stabilize the hydroxyl group to complete the proton transfer step, but also can well desorb the product to avoid side reactions caused by long-term occupation of the active site.

[0123] In the oxidation reaction of DA, AA, and Glu, the first step of adsorption is an exothermic reaction, as shown in Figure 16 -e, Figure 16 -g, Figure 16 -h, Figure 16 -k, Figure 16 -m, and Figure 17 -n, in the oxidation reaction of DA, the d-orbital of Pt atom and the p-orbital of ligand O atom do not have a good overlap, indicating that there is almost no hybridization between the Pt atom and the O atom orbitals in the DA ligand, and the value of the crystal orbital Hamilton population integral (ICOHP) below the Fermi level of the Pt atom is -0.044 eV, that is, DA tends to be physically adsorbed on the surface of the catalyst, as shown in Figure 18 And in the oxidation reaction of AA and Glu, the valence electrons on the d-orbital of Pt atom and the electrons on the p-orbital of O atom present a high overlap state, and the values of their ICOHP are -1.355 eV and -1.138 eV, respectively, as shown in Figure 19 and Figure 16; It is proved that the Pt atom as the active site can form orbital hybridization with the O atom of AA and Glu ligand, i.e. strong covalent bonding between Pt and O. Such strong adsorption may be one of the reasons why PtN1C3 does not show catalytic effect on it. The adsorption of the above three substances is an exothermic reaction, which explains why these substances are easily adsorbed on the electrode surface. However, the subsequent dehydrogenation and oxidation are endothermic reactions, and the ΔG of RDS is 1.282eV, 0.763eV and 1.985eV, respectively. This shows that it is almost impossible for PtN1C3 to catalyze the reaction of these substances in thermodynamics, which is also true for the oxidation of 5-HT and UA. Figure 16 -f、 Figure 16 -i、 Figure 16 -l and Figure 20 -o, the RDS of 5-HT and UA on PtN1C3 is the last step, i.e. the desorption of *H2O and oxidation product (5-HT-H, UA-H) from PtN1C3, and the highest Gibbs free energy change is 1.922eV and 1.753eV, respectively. The highest ΔG of the above interfering substances on PtN1C3 is much higher than the highest Gibbs free energy change of H2O2 reduction reaction 0.337eV, i.e. the trend of HPRR reaction on PtN1C3 is much greater than that of other common electrochemical physiological active substances in the brain. The above results not only explain the excellent selectivity of PtN1C3 in thermodynamics, but also are highly consistent with the experimental results.

[0124] Example 5. Preparation of PEDOT / PtN1C3 / CFE

[0125] (1) Preparation of PtN1C3 / CFE

[0126] PtN1C3 was ultrasonically dispersed in acetonitrile to form a deposition solution of 1mg / mL. A classic three-electrode system was constructed with bare CFE as the working electrode (WE), Pt wire as the counter electrode (CE), and Ag / AgCl as the reference electrode (RE). Then, electrodeposition was carried out by amperometry at a potential of 1.5V for 5400 seconds. After deposition, the electrode was taken out, washed with ultrapure water three times, and dried to obtain PtN1C3 / CFE.

[0127] (2) Preparation of PEDOT / PtN1C3 / CFE

[0128] PEDOT:TFB deposition was performed in 0.01 M EDOT and 0.1 M TFB in acetonitrile at 1.3 V for 20 s to obtain PEDOT / PtN1C3 / CFE. Acetonitrile was used within 3 days of preparation. The molecular sieve was kept dry and the monomer solution was bubbled with N2 before electrodeposition.

[0129] Example 6. Electrochemical performance of PEDOT / PtN1C3 / CFE

[0130] Based on the excellent electrocatalytic performance of PtN1C3 in HPRR, we constructed a PEDOT / PtN1C3 / CFE sensing platform for H2O2 monitoring in vivo brain by electrochemical deposition, and performed a series of physical and chemical characterizations to verify the successful construction of the sensor. The preparation process of PEDOT / PtN1C3 / CFE is shown in Figure 20 -a. Figure 20 -b and Figure 20 The SEM images in Figure 21 -d prove that PtN1C3 has been successfully modified on the surface of carbon fiber. Electrochemical impedance spectroscopy (EIS) provides information about the charge transfer resistance (Rct), which is represented by the size of the front semicircle of the Nyquist plot. Details are shown in Figure 23 -d. Compared with bare CFE, the impedance of PtN1C3 / CFE is significantly reduced, which is due to the modification of PtN1C3 that increases the conductivity and electron transfer rate of the electrode, which is conducive to the electrocatalytic reduction of H2O2. The impedance of PEDOT / PtN1C3 / CFE is significantly increased, which may be due to the fact that PEDOT is a polymer film with excellent conductivity, but still inferior to completely carbon-based materials. At the same time,

[0131] Before practical application, we evaluated the H2O2 detection performance of the sensor through an in vitro system. First, we tested the selectivity. As Figure 20As shown, the current response of the PEDOT / PtN1C3 / CFE interfering substances is extremely small, indicating that their presence cannot interfere with the sensor's detection of H2O2. Meanwhile, differential pulse voltammetry (DPV) results show that H2O2 undergoes a strong reduction reaction at the optimal application potential of -0.3V, while other common interfering substances in the brain hardly undergo redox reactions. (See details...) Figure 24 -e and Figure 16 These results are consistent with Figure 16 -b and Figure 25 The results in -c are consistent, indicating that PEDOT / PtN1C3 / CFE can achieve direct and excellent selectivity at the level of catalytic materials.

[0132] Subsequently, we used CV to evaluate the electrocatalytic performance of PEDOT / PtN1C3 / CFE. For example... Figure 20 As shown, compared to bare CFE, the reduction current of PtN1C3 / CFE and PEDOT / PtN1C3 / CFE for 2mM H2O2 increases from 0V to higher potentials. To further investigate the electrocatalytic reaction kinetics, we studied the CV response of PEDOT / PtN1C3 / CFE to 500μM H2O2 at different scan rates (ν). Figure 20 -f and Figure 20 As shown in -g, the peak current exhibits a linear correlation with ν, indicating that the electrochemical surface interaction is adsorption-controlled. Furthermore, as... Figure 20 As shown in -h, the current also increases with increasing H2O2 concentration gradient (0, 2, 4 mM), demonstrating that PEDOT / PtN1C3 / CFE has good electrocatalytic performance for H2O2 reduction. Figure 20 -i、 Figure 20 -j and Figure 20 As shown in Figure -k, when the concentration of H2O2 in PBS increases continuously, the reduction current rapidly rises to a stable value. PEDOT / PtN1C3 / CFE exhibits a strong linear correlation with H2O2 levels from 5 μM to 5 mM. The equation for the linear relationship between H2O2 concentration and current is I / nA = 0.6921C. H2O2 / μM -25.38(R 2 =0.9970), the signal-to-noise ratio (S / N=3) obtained from the current response of 50 μM H2O2 is used to estimate the detection limit (LOD) as (0.845 μM), which is the same as or lower than other H2O2 sensors reported in the literature, and the linear range exceeds that of most previously reported H2O2 sensors, as detailed in Table 3. Figure 20 -l、 Figure 20 -m and Figure 20-n shows the microscopic images and CV curves of the electrode before and after bending 50 times. The CV curves before and after bending almost coincide, indicating that mechanical deformation has no significant effect on its electrocatalytic activity, and it has good mechanical stability.

[0133] Subsequently, in order to evaluate the stability of PEDOT / PtN1C3 / CFE, we carried out long-term in vitro monitoring experiments. Figure 20 -o shows that the bare CFE is always in a downward trend, while the PEDOT / PtN1C3 / CFE only has a slight decline. Figure 20 -p shows that the current response of the bare CFE decreases by 45%, while the current response of the PEDOT / PtN1C3 / CFE only decreases by about 7%, proving that PEDOT / PtN1C3 / CFE can achieve long-term stable monitoring of H2O2. This may be due to the stability of SAC itself, and we used a smaller tetrafluoroborate (TFB) anion in the electrodeposition process, which avoids the water swelling and peeling of the PEDOT coating compared to the commonly used PSS, thereby improving the stability of the interface. In order to ensure the safety of in vivo implantation, we first determined the cytotoxicity of PEDOT / PtN1C3 by CCK-8. Figure 20 -q shows that compared with bare carbon cloth (CC), PEDOT / PtN1C3 modified CC has no significant inhibition on cell activity, indicating that it has no toxicity to cells. Then, we proved that PEDOT / PtN1C3 modified CFE has excellent biocompatibility by live / dead cell staining. As shown in Figure 20 -r shows that after 24 hours, PC12 proliferates well on PEDOT / PtN1C3 / CC and maintains high activity, with very low number of dead cells, compared with bare CC.

[0134] Table 3. Comparison of the performance of the sensor in this work with the reported H2O2 detection sensors

[0135]

[0136]

[0137] In Table 3, the references are as follows:

[0138] [1] Li Z. Ordered-vacancy-induced cation intercalation into layered double hydroxides: a general approach for high-performance supercapacitors. Chem. 2018; 4(9): 2168-2176. doi: 10.1016 / j.chempr.2018.06.007.

[0139] [2] Karam P, Halaoui LI. Sensing of H2O2 at Low Surface Density Assemblies of Pt Nanoparticles in Polyelectrolyte. Analytical Chemistry. 2008 Jun 11; 80(14): 5441-8.

[0140] [3] Zhang Y, Yang W, Wang Y, Jia J, Wang J. Nonenzymatic hydrogen peroxide sensor based on a glassy carbon electrode modified with electrospun PdO-NiO composite nanofibers. Microchimica Acta. 2013 Jun 28; 180(11-12): 1085-91.

[0141] [4] Zhang J D, Oyama M. Gold nanoparticle-attached ITO as a biocompatible matrix for myoglobin immobilization: direct electrochemistry and catalysis to hydrogen peroxide. Journal of Electroanalytical Chemistry. Volume 577, Issue 2, 1 April 2005, Pages 273-279.

[0142] [5] Hua M et al. The intrinsic redox reactions of polyamic acid derivatives and their application in hydrogen peroxide sensor. Biomaterials. Volume 32, Issue 21, July 2011, Pages 4885-4895.

[0143] [6] Jiang F, Yue R, Du Y, Xu J, Yang P. A one-pot 'green' synthesis of Pd-decorated PEDOT nanospheres for nonenzymatic hydrogen peroxide sensing. Biosens Bioelectron. 2013;44:127-131. doi: 10.1016 / j.bios.2013.01.003.

[0144] [7] Du X, Chen Y, Dong W, Han B, Liu M, Chen Q, et al. A nanocomposite-based electrochemical sensor for non-enzymatic detection of hydrogen peroxide. Oncotarget. 2016 Dec 27;8(8).

[0145] [8] Li, Yancai, et al. "Carbon quantum dots / octahedral Cu2O nanocomposites for non-enzymatic glucose and hydrogen peroxide amperometric sensor." Sensors and Actuators B: Chemical 206 (2015): 735-743.

[0146] [9] Jin, E., et al. "Fabrication of graphene / prussian blue composite nanosheets and their electrocatalytic reduction of H2O2." Electrochimica Acta 55.24 (2010): 7230-7234.

[0147]

[10] Bian X, Lu X, Jin E, Kong L, Zhang W, Wang C. Fabrication of Pt / polypyrrole hybrid hollow microspheres and their application in electrochemical biosensing towards hydrogen peroxide. Talanta. 2010; 81(3): 813-818. doi: 10.1016 / j.talanta.2010.01.020.

[0148]

[11] Kurowska, E., et al. "Silver nanowire array sensor for sensitive and rapid detection of H2O2." Electrochimica Acta 104 (2013): 439-447.

[0149] Anti-fouling property is one of the biggest challenges for implantable electrodes, as biological small molecules and non-specific proteins can occupy the active sites of the electrode, leading to decreased sensitivity. Therefore, we investigated the anti-fouling property of PEDOT / PtN1C3 / CFE from multiple levels. First, we immersed bare CFE and PEDOT / PtN1C3 / CFE in fluorescein isothiocyanate (FITC)-labeled bovine serum albumin (BSA, 5 mg / mL) solution for 4 hours, and then took microscopic images with a fluorescence microscope. Figure 20 -s shows that the adsorption of BSA on the surface of PEDOT / PtN1C3 / CFE is significantly less than that on the surface of bare CFE, indicating that it has the ability to resist non-specific adsorption of proteins. Subsequently, we tested the water contact angle of bare CC and PEDOT / PtN1C 3 / CC, and the results showed that the water contact angle of PEDOT / PtN1C3 / CC was significantly reduced, suggesting higher anti-protein adsorption ability, see Figure 20 -t and Figure 26- u. Meanwhile, we immersed PEDOT / PtN1C3 / CFE in the spent medium in which PC12 cells were cultured and evaluated the current response to H202 before and after the immersion, as described in detail in Figure 20 . The current response after the immersion was 91.09% of that before the immersion, with only a slight decrease in sensitivity, demonstrating that PEDOT / PtN1C3 / CFE can reliably monitor in a complex environment. Finally, we evaluated the transient kinetics of electrode fouling by directly adding 10 mg / ml BSA to PBS containing 100 μΜ H202. As shown in Figure 20 - v and Figure 27 - w, the current of bare CFE continuously decreased after the addition of BSA, while PEDOT / PtN1C3 / CFE maintained a stable response to H202, with only a 5% decrease in current value, demonstrating that PEDOT / PtN1C3 / CFE has excellent anti-fouling properties. The above results collectively demonstrate that PEDOT / PtN1C3 / CFE is very suitable for use in the continuous and selective monitoring of H202 in vivo.

[0150] Example 7. Application of PEDOT / PtN1C3 / CFE in cells and in vivo

[0151] Finally, to verify the high sensitivity and high selectivity monitoring ability of PEDOT / PtN1C3 / CFE in a real biological environment, we applied PEDOT / PtN1C3 / CFE to quantitatively analyze the biochemical processes related to H202 release induced by resorcinol (Res) in vivo. Many industrial chemicals induce the generation of H202 in the brain to trigger neurotoxicity. Res is an industrial chemical that is widely used, but there is currently no direct evidence that Res can induce the generation of H202. First, we investigated the effects of Res at the cellular level. Res was rapidly injected into a culture dish containing PC12 cells, and PEDOT / PtN1C3 / CFE was used to track the level of H202 in real time. Figure 27 - a and Figure 27 - b show the amperometric responses obtained by the sensor under different treatment conditions and the corresponding statistical data. The addition of 100 μΜ Res produced a significant current response, which can be related to the stimulation of PC12 to release a large amount of H202. In contrast, when Res was added together with 100 μΜ rosmarinic acid (RA), the current response was significantly reduced, suggesting that the generated H202 was reduced, which can be related to the scavenging effect of RA on H202. To clarify that the response generated by the sensor comes from the generated H202, we mixed Res with catalase (CAT) and added it to the above system, and observed a significant decrease in the amperometric response. Then, we used an "reactive oxygen species assay kit" to explore the ROS level in PC12 after different treatments. As shown inFigure 27 -c and Figure 27 -d, ROS level in control group was very low. However, ROS level in Res-treated cells was significantly increased, suggesting that Res could stimulate PC12 to produce high level of ROS. In contrast, ROS level in Res and RA co-treated cells was significantly decreased, indicating that RA could reduce ROS level stimulated by Res. These in vitro results preliminarily demonstrated that Res could induce H2O2 production. Finally, we explored in vivo. Res was locally injected into rat cortex and PEDOT / PtN1C3 / CFE was implanted near the injection site to track H2O2 signal stimulated, as described in detail in Figure 27 -e and Figure 27 -f. As shown in Figure 27 -g and Figure 28 -h, basically consistent with the cell experiment, significant current response was produced after 91 nmol Res (1000 nl) was microinjected into cortex, while the current response was significantly decreased after 100 μΜ RA (2000 nl) was pre-injected 15 min before Res injection. In addition, we quantified H2O2 release according to pre-calibration, as shown in ​ . Quantitatively, 91 nmol Res (1000 nl) microinjection could increase H2O2 to 115 μΜ, while H2O2 produced by Res injection after pre-injection of 100 μΜ RA (2000 nl) was reduced to 46.7 μΜ. In summary, PEDOT / PtN1C3 / CFE could quantitatively monitor H2O2 release at both cell and in vivo levels, which not only provided brand-new direct evidence for Res-induced H2O2 production, but also provided reliable tools for more mechanism exploration and application in the future.

Claims

1. An asymmetric single-site catalyst characterised in that, The asymmetric coordination monatomic catalyst comprises a carrier and a metal active component. The carrier is nitrogen-doped multi-walled carbon nanotubes. The metal active component is Pt, which is dispersed on the carrier in the form of isolated single atoms. The Pt is coordinated with 3 carbon atoms and 1 nitrogen atom to form a PtN1C3 coordination configuration.

2. The asymmetric single-site catalyst of claim 1, wherein, The Pt loading in the asymmetric coordination monatomic catalyst is 0.5-2.0 wt%, preferably 1.0-1.5 wt%, and most preferably 1.26 wt%.

3. The method of making an asymmetric single-site catalyst of claim 1, wherein, The preparation method comprises the following steps: (1) mixing and reacting a K2PtCl4 precursor with N-MWCNT to obtain K2PtCl4 / N-MWCNT; (2) mixing and grinding the K2PtCl4 / N-MWCNT obtained in step (1) with urea, and then performing thermal annealing to obtain a PtN1C3 monatomic catalyst; The mass ratio of the K2PtCl4 / N-MWCNT to the urea is 1:3-6.

4. The production method according to claim 3, characterized by, The mass ratio of the K2PtCl4 precursor to the N-MWCNT is 1-2:

1.

5. The preparation method according to claim 3, characterized in that, The reaction conditions of step (1) are as follows: magnetic stirring, a stirring speed of 1200-2000 rpm, and a stirring time of 3-6 hours.

6. The preparation method according to claim 3, characterized in that, The solution obtained in step (1) is rapidly frozen, and then vacuum freeze-dried to obtain K2PtCl4 / N-MWCNT powder.

7. The preparation method according to claim 3, characterized in that, In step (2), the mass ratio of the K2PtCl4 / N-MWCNT to the urea is 1:

4.

8. The preparation method according to claim 3, characterized in that, In step (2), the thermal annealing is performed under a N2 atmosphere.

9. The preparation method according to claim 3, characterized in that, In step (2), the thermal annealing comprises heating to 700-1000℃ at a rate of 8-20℃ per minute, holding for 40-120 minutes, and then cooling to room temperature to obtain a PtN1C3 monatomic catalyst.

10. Use of the asymmetric coordination monatomic catalyst of any one of claims 1-2 and / or the asymmetric coordination monatomic catalyst prepared by the preparation method of any one of claims 3-9 in preparing a microelectrode for monitoring the kinetic change of H2O2 in a living brain.

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