Pd-doped mn02 carbonaceous bottle-like micromotor and application thereof

Abstract

The application belongs to the field of micro-nano materials, and discloses a Pd-doped MnO2 carbon bottle-shaped micro motor and application thereof. Results show that the synergistic effect of Pd and MnO2 effectively enhances the near-infrared light absorption capacity and photo-thermal conversion performance of the material, and the rich oxygen vacancies further promote the formation of local thermal gradient, so that the micro motor shows good self-thermal swimming motion behavior under 808 nm laser irradiation. Based on the temperature change (ΔT) and the motion speed change (ΔV), a double signal response mode is constructed, which can realize efficient identification and accurate differentiation of five organic acids. PCA results show that different organic acids have good clustering separation effect under different concentration conditions, proving that the platform has high identification sensitivity and stability. Compared with the traditional single signal sensing method, the static-dynamic double signal strategy proposed in the present study effectively improves the detection accuracy and discrimination ability.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano materials, specifically relating to a Pd-doped MnO2 carbon bottle-shaped micromotor and its applications. Background Technology

[0002] Organic acids are widely found in environmental water bodies, food processing, biological fluids, and chemical production. Accurate identification and quantitative detection of their types and concentrations are of significant practical importance and application value for environmental monitoring, food safety control, biomedical diagnosis, and chemical process optimization. Currently, the detection methods for organic acids mainly rely on sophisticated instruments such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and mass spectrometry (MS). While these methods offer high detection accuracy, they suffer from drawbacks such as expensive equipment, complex operating procedures, long detection cycles, and the need for professional personnel, making them unsuitable for real-time detection and rapid on-site screening, thus limiting their versatility and widespread adoption. To address the shortcomings of traditional detection methods, various sensing technologies are gradually being applied to the field of organic acid detection. Among them, array sensing platforms have become a research hotspot due to their advantages such as multi-signal coordinated response, strong anti-interference capabilities, and the ability to simultaneously identify multiple targets. However, existing organic acid array sensing platforms are mostly based on static response signals, resulting in problems such as low response sensitivity, single signal, and insufficient recognition resolution, making it difficult to accurately distinguish between structurally similar organic acids.

[0003] As a type of micro-nano device that can convert external energy into autonomous motion kinetic energy, micromotors, with their advantages of small size and autonomous controllable motion, can effectively promote sample solution mixing, improve mass transfer efficiency, shorten detection time, and achieve in-situ detection in ultra-small volume samples, providing a new approach for performance optimization of sensing platforms. Although micromotors combined with static-dynamic array sensing strategies have shown great potential, the technology still faces the following challenges: (1) The driving methods of existing micromotor systems are relatively simple. Some chemical fuel-driven micromotors rely on external fuels such as high-concentration hydrogen peroxide, which not only affects the stability of the detection system but may also interfere with complex sample environments, thus limiting their application in actual samples. (2) The photothermal conversion efficiency and energy utilization efficiency of most micromotor materials are limited, resulting in insufficient driving force and poor motion stability, making it difficult to achieve continuous and efficient active mass transfer and signal amplification. (3) The current micromotor array sensing system still needs to improve its ability to identify small molecules with similar structures such as different organic acids, especially in complex systems, where problems such as overlapping response modes, insufficient selectivity, and decreased classification accuracy are prone to occur. (4) Existing static sensing strategies mainly rely on a single signal output, which has limited information dimensions. The coupling mechanism between dynamic behavior parameters and chemical response is still unclear, which means that the advantages of micro motor motion behavior in array recognition have not been fully utilized.

[0004] Therefore, further research is needed to address the shortcomings of existing organic acid detection technologies and the deficiencies of array sensing platforms, by combining the dynamic advantages of micromotors with the functional characteristics of composite nanomaterials. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one deficiency of the prior art and to provide a Pd-doped MnO2 carbon bottle-shaped micromotor and its application.

[0006] The technical solution adopted in this invention is:

[0007] In a first aspect, the present invention provides a Pd-doped MnO2 carbon bottle-shaped micromotor, which is prepared by the following method steps:

[0008] 1) Disperse P123 and sodium oleate in water, then introduce carbon precursor for heat treatment to obtain carbon nano flasks, namely HCBs-16.

[0009] 2) Disperse KMnO4 in the HCBs-16 obtained in step 1, and grow MnO2 uniformly on its surface through in-situ redox reaction to obtain MnO2@HCBs-16;

[0010] 3) PdCl2 is introduced into the MnO2@HCBs-16 obtained in step 2 to carry out the reaction, and Pd-doped MnO2 carbon bottle-shaped micromotor is obtained.

[0011] Optionally, the carbon precursor is selected from ribose.

[0012] Optionally, the mass ratio of sodium oleate to P123 is 1:(1.1-1.8).

[0013] Optionally, the mass ratio of sodium oleate to ribose is 1:(80-100).

[0014] Optionally, the heat treatment temperature in step 1) is 155-175 °C.

[0015] Optionally, the heat treatment time in step 1) is 11.5-24.5 h.

[0016] Optionally, the mass ratio of KMnO4 to HCBs-16 is 1:(9.5-13.5).

[0017] Optionally, the mass ratio of PdCl2 to MnO2@HCBs-16 is 1:(4.5-8.5).

[0018] Secondly, the application of the Pd-doped MnO2 carbonaceous bottle-shaped micromotor provided in the first aspect of the present invention in the preparation of organic acid detection materials.

[0019] The organic acid may be selected from ascorbic acid, citric acid, malic acid, tartaric acid, and oxalic acid.

[0020] The beneficial effects of this invention are:

[0021] This invention successfully fabricated a Pd-MnO2@HCBs-16 carbon-based bottle-shaped micromotor and, based on its excellent photothermal response and autonomous motion performance, constructed a static-dynamic dual-signal array sensing platform for the recognition of various organic acids. Results show that the synergistic effect of Pd and MnO2 effectively enhances the near-infrared light absorption and photothermal conversion performance of the material. Abundant oxygen vacancies further promote the formation of local thermal gradients, enabling the micromotor to exhibit excellent autothermal phoretic motion behavior under 808 nm laser irradiation. A dual-signal response mode based on temperature change (ΔT) and motion velocity change (ΔV) enables efficient recognition and accurate differentiation of five organic acids. PCA results show that different organic acids exhibit good clustering and separation effects under various concentration conditions, demonstrating that the platform has high recognition sensitivity and stability. Compared with traditional single-signal sensing methods, the static-dynamic dual-signal strategy proposed in this study effectively improves detection accuracy and discrimination ability. In summary, this study provides a novel micromotor sensing strategy for the rapid detection and multi-component identification of complex organic acid systems, which has promising application prospects in fields such as food safety, environmental monitoring, and bioanalysis. Attached Figure Description

[0022] Figure 1 The following are the relevant spectra of the synthesis of Pd-MnO2@HCBs-16: (A) Figure is a schematic diagram of the synthesis route of Pd-MnO2@HCBs-16 micromotor; (B), (C), and (D) Figures are SEM images of HCBs-16, MnO2@HCBs-16 and Pd-MnO2@HCBs-16; (E) and (F) Figures are TEM and HRTEM images of Pd-MnO2@HCBs-16; (G) Figure is a magnified view of the lattice fringes of Pd-MnO2@HCBs-16 and (H) the corresponding interplanar spacing diagram; (I) Figure is a HAADF-STEM image of Pd-MnO2@HCBs-16; (J), (K), (L), (M), and (N) Figures are elemental mapping analysis diagrams of each element.

[0023] Figure 2The following are the photothermal performance analysis diagrams of the Pd-MnO2@HCBs-16 micromotor: (A) The diagram shows the UV absorption spectra of HCBs-16 (a), MnO2@HCBs-16 (b), and Pd-MnO2@HCBs-16 (c); (B) and (C) The diagrams show the UV absorption spectra of different samples (H2O (a), HCBs-16 (b), MnO2@HCBs-16 (c), and Pd-MnO2@HCBs-16 (d)) at 1.5 W / cm². 2 Photothermal heating curves and corresponding thermal images under near-infrared light irradiation; (D) Photothermal heating curves of Pd-MnO2@HCBs-16 at different concentrations (af: 75, 100, 125, 150, 175 and 200 μg / mL); (E) Photothermal heating curves of Pd-MnO2@HCBs-16 at different laser power densities (ae: 0.5, 0.75, 1.0, 1.25 and 1.5 W / cm²). 2 (a) Photothermal heating curves of HCBs-16 (a), MnO2@HCBs-16 (b), and Pd-MnO2@HCBs-16 (c) and their corresponding photothermal conversion efficiencies, respectively; (H) Photothermal stability test of Pd-MnO2@HCBs-16 during 4 cycles of heating-cooling; (I) Electron paramagnetic resonance (EPR) spectra of HCBs-16 (a), MnO2@HCBs-16 (b), and Pd-MnO2@HCBs-16 (c).

[0024] Figure 3 This is a motion performance analysis of the Pd-MnO2@HCBs-16 micromotor under different near-infrared light intensities. Specifically: Figure (AF) shows the motion trajectory of Pd-MnO2@HCBs-16 under different near-infrared light intensities, where the blue dot represents the initial time (0 s) and the red dot represents the final time (3 s); Figures (G), (H), and (I) show the motion trajectory of Pd-MnO2@HCBs-16 under different near-infrared light intensities (AF: 0, 0.5, 0.75, 1.0, 1.25, and 1.5 W / cm²). 2 The mean square displacement-time variation curve, average velocity, and diffusion coefficient of Pd-MnO2@HCBs-16.

[0025] Figure 4 This is a principal component analysis score chart of five organic acids at different concentrations (0.005-30 μM) using (AF). Detailed Implementation

[0026] The following disclosure provides many different implementations or examples for different ways of implementing the present invention.

[0027] Pd-MnO2@HCBs-16 micromotors were prepared through a sequential process of soft template polymerization, redox deposition, and Pd doping. First, P123 and sodium oleate were dispersed in water, forming mixed micelles driven by hydrophobic interactions. Ribose was then introduced as a carbon precursor, and the mixture was heat-treated in an oven. When the temperature rose to approximately 160 °C, the hydrogen bonding between polyethylene glycol (PEO) segments in P123 and water molecules weakened, leading to a decrease in the hydration of the PEO segments. The enhanced hydrophobic interactions further promoted the penetration of PEO blocks into the mixed template, causing structural expansion and crack formation in areas where the carbon shell was relatively thin. Simultaneously, ribose molecules diffused into the interior, causing the confined surfactant to be extruded outwards. Subsequently, ribose polymerized along the inner wall, and the extruded surfactant continued to act as a soft template, guiding directional polymerization growth at the shell cracks, ultimately yielding a carbon nanoflask (HCBs-16) with an open structure. During the MnO2 deposition process, KMnO4 was dispersed in an aqueous suspension of HCBs-16, and MnO2 was uniformly grown on its surface through an in-situ redox reaction. Finally, PdCl2 was introduced into MnO2@HCBs-16 to obtain Pd-MnO2@HCBs-16 micromotors with enhanced photothermal properties and autonomous movement capabilities.

[0028] Example 1

[0029] This embodiment provides a synthesis of a Pd-doped MnO2 carbonaceous bottle-shaped micromotor (Pd-MnO2@HCBs-16), the process of which is as follows. Figure 1 A. The specific synthesis method is as follows:

[0030] 1) First, 0.073 g of sodium oleate and 0.087 g of P123 were dissolved in 40 mL of ultrapure water and stirred for 30 min to obtain a clear and homogeneous solution A. Simultaneously, 6 g of ribose was dispersed in 80 mL of ultrapure water and stirred for 5 min to obtain solution B. Then, solution A was poured into solution B to obtain a mixed solution. The mixed solution was magnetically stirred for 30 min and then transferred to a high-pressure reactor, heated at 160 °C for 12 h to obtain an open-structure carbon nanofiber flask (HCBs-16).

[0031] 2) Subsequently, 100 mg HCBs-16 and 10 mg potassium permanganate were dispersed in 10 mL of ultrapure water, ultrasonicated to obtain a uniform suspension, and stirred at 25 °C for 12 h to obtain MnO2@HCBs-16.

[0032] 3) Finally, 100 mg MnO2@HCBs-16 was dispersed in 10 mL of water, sonicated for 10 min, and then 20 mg of palladium chloride (PdCl2) was added. After reacting for 5 h, the precipitate was washed three times each with water and ethanol, and then dried under vacuum to obtain Pd-MnO2@HCBs-16.

[0033] The specific material characterization results are as follows:

[0034] To further reveal the morphological and structural evolution of the material at different construction stages, the obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).

[0035] like Figure 1 As shown in B–1D, the SEM images clearly demonstrate the morphological evolution of the material at different construction stages. HCBs-16 exhibits a uniform asymmetric flask-shaped morphology with a narrow size distribution and a relatively smooth surface. Figure 1 B). After in-situ growth of MnO2 and subsequent Pd doping / etching, the surfaces of both MnO2@HCBs-16 and Pd-MnO2@HCBs-16 became significantly rougher. Figure 1 (C-1D), indicating that MnO2 and Pd have been successfully deposited on the carbonaceous framework surface. This rough heterogeneous surface is beneficial for establishing a local interface temperature gradient during subsequent photothermal driving processes.

[0036] TEM image ( Figure 1 E) Further confirmation indicates that Pd-MnO2@HCBs-16 possesses a typical hollow flask-like structure with clearly discernible internal cavity boundaries, demonstrating that the anisotropic cavity structure has been successfully constructed via a soft-template-guided polymerization process. Simultaneously, a distinct high-contrast region was observed on the shell, indicating that the high-electron-density metal components (Mn and Pd) have been successfully loaded onto the shell surface. Figure 1 As shown in Figure F, the magnified HRTEM image of the surface region reveals clear and regular lattice fringes with a plane spacing of approximately 0.225 nm, which belong to the Pd(111) plane.

[0037] Lattice fringes were extracted using inverse Fourier transform (FFT). Figure 1 G, where the regular periodic diffraction fringes further demonstrate that the Pd nanoparticles embedded in the micromotor structure have high crystallinity, and the line intensity distribution curve of the lattice fringes ( Figure 1 H) further validated the measured interplanar spacing. Furthermore, the HAADF-STEM image ( Figure 1 I) It shows a complete flask-shaped outline, which is highly consistent with the TEM observation results.

[0038] Element mapping results ( Figure 1 J-1N indicates that C, O, Mn, and Pd elements are uniformly distributed throughout the micromotor structure, with Pd signal mainly enriched in the shell region, further confirming its successful loading onto the MnO2@HCBs-16 framework surface. This uniform elemental distribution enhances near-infrared light capture capability and provides a structural basis for subsequent oxygen vacancy regulation and photothermal performance improvement.

[0039] Photothermal Performance Analysis of Pd-MnO2@HCBs-16 Micromotors

[0040] In this embodiment, a static-dynamic dual-signal array sensor was developed using a Pd-MnO2@HCBs-16 micromotor as a response probe to achieve the detection and differentiation of five organic acids (ascorbic acid (AA), citric acid (CA), malic acid (MA), tartaric acid (TTA), and oxalic acid (OA)).

[0041] Specifically, solutions of five organic acids with different concentrations were prepared, and equal volumes of micromotor dispersions were mixed with these solutions. Temperature and motion signals were simultaneously acquired under 808 nm near-infrared laser irradiation at the same power density. The static sensing unit was constructed based on photoinduced temperature response; under the same near-infrared irradiation conditions, the system temperatures before and after the addition of the target organic acid were recorded, denoted as T0 and T. The dynamic sensing unit, under the same near-infrared irradiation conditions, used the change in the average speed of the micromotor as the output signal. The motion trajectory of the micromotor before and after the addition of the target organic acid was recorded using an inverted fluorescence microscope, and the coordinates of the motion trajectory and the corresponding average speed were extracted using Python, denoted as V0 and V. Finally, ΔT(T-T0) and ΔV(V-V0) were integrated into a two-dimensional feature vector to construct a dual-signal response matrix for principal component analysis (PCA) to identify and distinguish the five organic acids.

[0042] Since the localized thermal gradient induced by light absorption is considered the main energy source driving the autothermal phoretic motion of micro / nanostructures, it is necessary to systematically elucidate the photothermal response behavior of the constructed carbon-based materials and composites. To evaluate the light-harvesting ability of different materials, the UV-vis absorption spectra of all samples were recorded.

[0043] like Figure 2 As shown in Figure A, HCBs-16 exhibits a distinct absorption band in the ultraviolet region, which is mainly attributed to sp... 2The π–π* electronic transitions of the conjugated carbon framework. In contrast, HCBs-16 exhibits weak absorption in the 650–900 nm region, indicating limited utilization of near-infrared light and hindering efficient photothermal conversion. After modification with MnO2, the absorption of MnO2@HCBs-16 in the 650–900 nm region is significantly enhanced, with a redshift of the absorption edge, a phenomenon attributable to the narrow bandgap semiconductor characteristics of MnO2. Further introduction of Pd further enhances the absorption intensity of Pd-MnO2@HCBs-16 in the 650–900 nm region, which may be related to the generation of additional oxygen vacancies in MnO2.

[0044] Subsequently, the photothermal heating behavior of different samples under 808 nm laser irradiation was evaluated. For example... Figure 2 As shown in Figure B, under the same laser power density and sample concentration, the temperature difference (ΔT) of Pd-MnO2@HCBs-16 relative to room temperature is significantly higher than that of MnO2@HCBs-16 and HCBs-16, indicating that it has superior photothermal properties. Furthermore, pure water also exhibits a slight temperature rise under near-infrared irradiation, mainly attributed to the inherent weak absorption of 808 nm laser light by water molecules. The absorbed photon energy can be converted into heat through OH bond vibration relaxation. In addition, the weak light absorption of the experimental container and local heat accumulation may also contribute to this phenomenon.

[0045] To further demonstrate the material's excellent photothermal response behavior, infrared thermal imaging was used to monitor the heating process in real time. For example... Figure 2 As shown in Figure C, the Pd-MnO2@HCBs-16 dispersion exhibits a color change from black to bright yellow during near-infrared irradiation, further confirming its efficient photothermal conversion capability and rapid localized heat generation characteristics.

[0046] Subsequently, the photothermal response behavior of Pd-MnO2@HCBs-16 was systematically investigated under different experimental conditions. For example... Figure 2 As shown in Figure D, the temperature difference gradually increases with increasing sample concentration. This indicates that higher concentrations provide more photothermal active sites for near-infrared light absorption, thereby promoting more efficient heat generation and achieving a more significant temperature rise.

[0047] like Figure 2 As shown in E, when the laser power density increases from 0.5 to 1.5 W / cm² 2 At this time, Pd-MnO2@HCBs-16 exhibited significant laser power-dependent heating behavior. This result indicates that higher photon flux is beneficial for improving photothermal conversion efficiency, thereby establishing a steeper local thermal gradient, which is extremely advantageous for the subsequent autothermal phoretic motion of the micromotor.

[0048] Meanwhile, the photothermal conversion efficiency (η) of HCBs-16, MnO2@HCBs-16, and Pd-MnO2@HCBs-16 was further calculated based on the heating-cooling curves. Figure 2 F-2G, Pd-MnO2@HCBs-16 exhibited the highest η value among all samples, indicating its superior photothermal conversion capability. Subsequently, the photothermal stability of Pd-MnO2@HCBs-16 was evaluated through multiple laser on / off cycle irradiation experiments. Figure 2 (H). After multiple cycles of irradiation, no significant decrease in the system's maximum temperature was observed, indicating that Pd-MnO2@HCBs-16 exhibits excellent photothermal stability under repeated near-infrared irradiation conditions. This stable photothermal performance provides a significant advantage for long-term driving and repetitive biosensing applications.

[0049] Finally, the presence of oxygen vacancies was verified through EPR testing, further revealing the intrinsic source of the enhanced photothermal performance. Figure 2 As shown in Figure I, Pd-MnO2@HCBs-16 exhibits a significantly enhanced characteristic EPR signal around a g value of 2.003, indicating that it has a richer number of oxygen vacancy defects.

[0050] Motion performance analysis of Pd-MnO2@HCBs-16 micromotor

[0051] To evaluate the photothermal driven motion behavior of the Pd-MnO2@HCBs-16 micromotor, its motion trajectory was recorded under different 808 nm laser power densities.

[0052] like Figure 3 As shown in A-3F, under no-light conditions, the micromotor exhibits only limited Brownian motion displacement. As the laser power density increases from 0.5 to 1.5 W / cm², the displacement decreases. 2 The length of its trajectory gradually increases, indicating a continuous enhancement in its motion capability. This is mainly attributed to the stronger local thermal gradient formed under higher near-infrared photon flux, which promotes a more significant autothermal propulsion effect. As the laser power density increases, the slope of the mean square displacement (MSD) curve gradually increases, indicating a significant acceleration in the displacement dynamics of the micromotor. Figure 3 D). Based on the MSD results, the effective diffusion coefficient (D) was further calculated. eff ).like Figure 3 As shown in H and 3I, D eff It monotonically increases with increasing laser power density, and reaches 1.5 W / cm². 2 The value reached its maximum, indicating a significant improvement in its active diffusion capability under stronger photothermal stimulation. Simultaneously, the average speed of the micromotor also showed a clear trend of increasing dependence on laser power, gradually increasing from unlit conditions to 1.5 W / cm². 2Further evidence demonstrates that enhanced photothermal conversion efficiency at higher laser power can establish a steeper interfacial thermal gradient, thereby providing stronger driving force for the autonomous movement of micromotors.

[0053] Static and Dynamic Array Sensing Performance Analysis of Pd-MnO2@HCBs-16 Micromotors

[0054] To verify the ability of the constructed Pd-MnO2@HCBs-16 micromotor array sensing platform to identify different organic acids, a dual-mode strategy combining static temperature signals and dynamic motion signals was adopted to distinguish and analyze five organic acids.

[0055] In the experiment, the Pd-MnO2@HCBs-16 micromotor dispersion was mixed with equal volumes of target organic acid solutions of different concentrations (0.005, 0.5, 5, 10, 20, 30 μM), and the photothermal temperature change and motion behavior change signals were collected simultaneously under the same power density 808 nm near-infrared laser irradiation conditions.

[0056] Subsequently, a two-dimensional response matrix was constructed using the temperature difference ΔT and velocity difference ΔV as dual-signal characteristic parameters, and principal component analysis (PCA) was used to identify patterns in different organic acids. Different organic acids exhibit differentiated interfacial interactions with the Pd-MnO2@HCBs-16 micromotor; their acidity, reducing power, and surface adsorption behavior all affect the local chemical environment and motion behavior of the micromotor. On one hand, the reduction effect of organic acids on the Pd-MnO2@HCBs-16 components alters the system's absorption capacity for near-infrared light, leading to varying degrees of photothermal temperature changes. On the other hand, different organic acids have different effects on the catalytic reaction and local concentration gradient regulation of the micromotor surface, further causing differences in motion velocity. Therefore, various organic acids can generate characteristic static-dynamic dual-signal response patterns, providing a foundation for subsequent array identification.

[0057] like Figure 4As shown in A-4F, the five organic acids exhibited good clustering and separation characteristics under different concentration conditions. PCA analysis results showed that the contribution rate of the first principal component (PC1) was mainly distributed between 81.3% and 96.0%, while the contribution rate of the second principal component (PC2) was 4.0% to 18.7%, with both having a cumulative contribution rate exceeding 90%, indicating that the established dual-signal feature can effectively reflect the differences between different organic acids. Specifically, under low concentration conditions (0.005-0.5 μM), the data points corresponding to different organic acids could already form relatively independent cluster regions, indicating that the array sensing platform has high recognition sensitivity. As the organic acid concentration further increased to 5-30 μM, the separation boundaries between the samples became clearer, and the overlap of cluster regions was reduced, indicating that the dual-signal mode can stably distinguish different targets. Notably, the static-dynamic dual-signal fusion strategy significantly improved the discrimination capability of the array sensor. Temperature response mainly reflects the influence of organic acids on the photothermal behavior of micromotors, while changes in motion speed are more sensitive to interfacial catalytic reactions and local mass transfer behavior. The two types of signals have good complementarity, which can effectively reduce the risk of misjudgment caused by single signal fluctuations and improve the system's accuracy and stability in identifying complex targets.

[0058] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A Pd-doped MnO2 carbon bottle-shaped micromotor, characterized in that, The Pd-doped MnO2 carbon bottle-shaped micromotor was prepared by the following steps: 1) Disperse P123 and sodium oleate in water, then introduce carbon precursor for heat treatment to obtain carbon nano flasks, namely HCBs-16. 2) Disperse KMnO4 in the HCBs-16 obtained in step 1, and grow MnO2 uniformly on its surface through in-situ redox reaction to obtain MnO2@HCBs-16; 3) PdCl2 is introduced into the MnO2@HCBs-16 obtained in step 2 to carry out the reaction, and Pd-doped MnO2 carbon bottle-shaped micromotor is obtained.

2. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1, characterized in that, The carbon precursor is selected from ribose.

3. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1, characterized in that, The mass ratio of sodium oleate to P123 is 1:(1.1-1.8).

4. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1 or 2, characterized in that, The mass ratio of sodium oleate to ribose is 1:(80-100).

5. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1, characterized in that, The heat treatment temperature in step 1) is 155-175 °C.

6. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1, characterized in that, The heat treatment time in step 1) is 11.5-24.5 h.

7. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1, characterized in that, The mass ratio of KMnO4 to HCBs-16 is 1:(9.5-13.5).

8. The Pd-doped MnO2 carbon bottle-shaped micromotor according to claim 1, characterized in that, The mass ratio of PdCl2 to MnO2@HCBs-16 is 1:(4.5-8.5).

9. The application of the Pd-doped MnO2 carbonaceous bottle-shaped micromotor according to any one of claims 1-8 in the preparation of organic acid detection materials.

10. The application according to claim 9, characterized in that, The organic acid is selected from ascorbic acid, citric acid, malic acid, tartaric acid, and oxalic acid.

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