Preparation and application of all-solid-state ion selective sensing chip

Abstract

The invention discloses a preparation method and application of an all-solid-state ion selective sensing chip, through a multi-metal active site regulation strategy, an ion-electron transduction interface of 3d transition metal cobalt sulfide (X-Co3S4, X = Mn, Fe, Co, Ni and Cu) derived on the basis of Co-LDH rich in micro / nano structures is developed, and the ion-electron transduction interface can be used for preparing the all-solid-state ion selective sensing chip. And a high-stability all-solid-state environment water quality hardness chip based on hydrophobic Cu-Co3S4 transduction is constructed. An expandable process for customizing the sensing chips in batches is provided, and large-scale manufacturing of the sensing chips is achieved through precise mold design and a tabletting forming technology. The Cu-Co3S4-based sensing chip capable of being customized on a large scale has high interface capacitance (568 [mu] F) and ultralow potential drift (the drift is 1.76 + / -0.01 [mu] V.s <-1 > within 36 hours), and shows good detection performance on Ca < 2 + > and Mg < 2 + >.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical sensing chip manufacturing, and specifically to the preparation and application of an all-solid-state ion-selective sensing chip. Background Art

[0002] The hardness of water (evaluated by the concentration of Ca 2+ and Mg 2+ ions) is a core indicator for water quality monitoring and is highly relevant to the domestic water safety of urban and rural residents and industrial production. Specifically, too high a concentration of calcium and magnesium ions in environmental water bodies is likely to cause scaling of industrial equipment, reduce energy efficiency and even cause explosions, reduce domestic water use efficiency and may affect the physical health of residents. Conversely, too low a concentration will affect the metabolism of aquatic organisms and thus damage the stability of the ecosystem. Therefore, the real-time monitoring of water hardness is crucial for ensuring drinking water safety, improving industrial production efficiency, and maintaining the balance of the ecological environment. With the rapid development of intelligent technology and microelectronics technology, miniaturizable intelligent monitoring systems have shown broad application prospects in solving the monitoring requirements of complex chemical environments. For example, Bouhoun et al. developed a paper-based water hardness potentiometric measurement platform, which realized the rapid monitoring of water hardness. It is reported that the potential stability of the sensing chip is limited by the interfacial water layer brought about by the water permeability of the ion-selective membrane (ISM) and the interfacial polarization caused by the asymmetric transduction process from the ISM to the conductive substrate. Materials such as carbon nanotubes, which have excellent electronic conductivity and good chemical stability, are used as the transduction layer. The high-capacitance interfacial transduction mechanism thereof depends on the double-capacitance charge storage of the pore structure, and it is difficult to ensure the uniformity of pores and the stability of the sensing chip in mass production. The pseudocapacitive interfacial stabilization mechanism involving surface redox reactions at the atomic level shows the potential for mass production. Therefore, customizing a transduction material with high hydrophobic ability and interfacial capacitance containing controllable pseudocapacitive sites is a potential solution for long-term use of the sensing chip.

[0003] Cobalt sulfide with a complex stoichiometric relationship exhibits unique advantages in the field of energy storage and conversion (such as supercapacitors) due to its high specific capacitance and energy density, fast kinetic response, and tunable structure. However, the inherently low conductivity of cobalt sulfide will exacerbate the problems of active material aggregation and structural collapse during the cycling process, resulting in a significant decrease in its electrochemical stability and limiting its further practical application. Introducing a second metal ion can construct abundant active sites, regulate the electronic structure of cobalt sulfide to optimize the overall electron distribution, provide an additional Faraday pseudocapacitance contribution to increase the charge storage capacity and improve the conductivity. At the same time, the introduction of the second metal ion can improve the mechanical stability and chemical stability of the material, which is crucial for long-term cycling performance. Two-dimensional layered double hydroxides (LDH) are composed of orderly arranged bimetallic ions (Mn 2+ / 3+ 、Fe2+ / 3+ , Co 2+ / 3+ , Ni 2+ / 3+ and Cu 1+ / 2+ )(Combined with interlayer anions to construct multi - level pseudocapacitive active centers, providing abundant active sites and contributing to the construction of a stable chemical structure. The capacitance performance can be effectively improved through metal component regulation and the sulfidation process. Therefore, cobalt - based LDH - derived sulfides have become an ideal substrate for the preparation of highly efficient second - metal - doped cobalt sulfides.)

[0004] Portable environmental water quality monitoring equipment has become a core tool in the environmental monitoring and governance system due to its fast response characteristics. Traditional monitoring equipment is vulnerable to factors such as temperature drift, sensor aging, and environmental interference, making it difficult to cope with the complex and changing natural water environment. Facing the problem of electrode loss during the long - term operation of the equipment, constructing a batch - manufacturable replaceable sensing chip can reduce maintenance costs and provide an effective solution for the intelligent sensing system to deal with pollution - induced failure. Therefore, we expect to propose a preparation process for batch - manufacturable chips based on customized transduction interface materials.) Summary of the Invention

[0005] In view of this, the present invention provides a preparation and application of an all - solid - state ion - selective sensing chip to solve the problems raised in the above - mentioned background technology. The core lies in using a strategically designed hydrophobic Co - based LDH - derived Cu - Co3S4 all - solid - state ion - selective sensing chip as the transduction layer. A scalable batch - customization preparation process for the sensing chip is proposed, and the scalable manufacturing of the sensing chip is realized through precise mold design and tablet pressing technology. Experiments show that the chip exhibits excellent detection performance with reproducibility, reversibility, and anti - interference in the detection of Ca 2+ and Mg 2+ , providing an engineering - feasible solution for constructing an intelligent water quality detection chip. Through the systematic optimization of multi - metal - site - regulated X - Co3S4 (X = Mn, Fe, Co, Ni, and Cu), it is confirmed that the Cu - Co3S4 system has the optimal interfacial capacitance (568 μF) and potential stability (the potential drift is only 1.76 ± 0.01 μV·s for 36 h continuously) -1 ).

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In the first aspect, the present invention discloses an all - solid - state ion - selective sensing chip material, which is composed of hydrophobic transition - metal cobalt sulfide; the transition metal X is at least one of Mn, Fe, Co, Ni, and Cu.)

[0008] In the second aspect, the present invention discloses a preparation method of the above - mentioned all - solid - state ion - selective sensing chip material, including the following steps:

[0009] S1. Add the soluble salt of transition metal X, the soluble salt of Co, the alkaline precipitant, and NH4F into deionized water. After stirring until it becomes clear, transfer it into a reaction kettle and react at 100 - 150 °C under sealed conditions for 4 - 6 h. Then filter to obtain the solid product X-Co-LDH. Among them, NH4F mainly provides NH4 + , serving as an auxiliary ammonia source, and F- acts as a structure-directing agent or mineralizer, affecting the crystallinity, lamellar charge distribution, or morphology of LDH;

[0010] S2. After uniformly stirring the solid product X-Co-LDH with the aqueous solution of sulfur source, transfer it into a reaction kettle and react at 100 - 140 °C under sealed conditions for 5 - 7 h to obtain the solid product X-Co3S4, that is, the hydrophobic transition metal sulfide.

[0011] Further scheme: In step S1, the soluble salt of transition metal X is the nitrate of X; the soluble salt of Co is Co(NO3)2·6H2O; the alkaline precipitant is urea; the aqueous solution of sulfur source is 0.1 M Na2S aqueous solution. Among them, urea serves as a pH regulator and precipitant.

[0012] Further scheme: In step S1, the molar ratio of the soluble salt of transition metal X, the soluble salt of Co, urea, and NH4F is (0 - 1):2:(5 - 20):(1 - 8).

[0013] Further scheme: In step S2, the molar ratio of the solution X-Co-LDH to the aqueous solution of sulfur source is (3 - 8):9.

[0014] In the third aspect, the present invention discloses a all-solid-state ion-selective sensing chip, which includes a first encapsulation housing, a second encapsulation housing nested in the first encapsulation housing, a transduction layer disposed in the second encapsulation housing, and an ion-selective membrane disposed on the surface of the transduction layer. Among them, the transduction layer of the all-solid-state ion-selective sensing chip material above is mixed with PVDF.

[0015] Further scheme: The mass ratio of the all-solid-state ion-selective sensing chip material to PVDF is 1:(1 - 10).

[0016] In the fourth aspect, the present invention discloses a all-solid-state ion-selective electrode, which uses the all-solid-state ion-selective sensing chip material prepared by the above preparation method as the transduction layer.

[0017] In the fifth aspect, the present invention discloses the application of the above all-solid-state ion-selective electrode in detecting the cation concentration in the environment, including calcium ion, magnesium ion concentration, and other ion species for evaluating environmental indicators.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. Through the directional regulation of active sites of the two-dimensional layered cobalt-based hydroxide precursor, a structurally stable derived sulfide system is constructed. This not only effectively inhibits the structural collapse of cobalt-based sulfides, but also synchronously retains the double-layer capacitance characteristics endowed by the inherent two-dimensional layered structure of cobalt-based LDH, as well as the pseudo-capacitance active sites of 3d transition metals formed through the regulation of active sites. This synergistic effect significantly enhances the interfacial capacitance and improves the stability of the interfacial potential.

[0020] 2. The present invention proposes a scalable batch manufacturing process for customized sensing chips, which realizes large-scale manufacturing through precision mold design and tablet pressing technology. Specifically: (1) A dual-mold system with a stepped structure (a copper mold with a gold-plated surface) is innovatively designed. The small mold (bottom radius 1.5 mm × height 2.5 mm) is used for precise molding of the sensitive material layer, and the large mold (bottom radius 1.75 mm × internal depth 2.5 mm) integrates the function of wire welding. It is precisely pressed and formed at 5 MPa to ensure uniform material density. The customized copper mold combines precise dimension design and welding process to ensure the stability and consistency of the interface. (2) A thermal protection pressing process is developed. After wire welding at 280 °C / 1 s, secondary pressing is carried out to effectively avoid the problem of material high-temperature deformation. At the same time, a target ion membrane is precisely coated on the chip surface, effectively improving the responsiveness and long-term stability of the sensor. Description of the Drawings

[0021] Figure 1 Scanning electron microscope photos of X-Co-LDH obtained in Examples 1-5. Among them, a-b show the scanning electron microscope results of Mn-Co-LDH, c-d show the scanning electron microscope results of Fe-Co-LDH, e-f show the scanning electron microscope results of Co-LDH, g-h show the scanning electron microscope results of Ni-Co-LDH, and i-j show the scanning electron microscope results of Cu-Co-LDH;

[0022] Figure 2 Scanning electron microscope photos of X-Co3S4 obtained in Examples 1-5. Among them, a-b show the scanning electron microscope results of Mn-Co3S4, c-d show the scanning electron microscope results of Fe-Co3S4, e-f show the scanning electron microscope results of Co3S4, g-h show the scanning electron microscope results of Ni-Co3S4, and i-j show the scanning electron microscope results of Cu-Co3S4;

[0023] Figure 3 Cyclic voltammetry test curves of X-Co3S4 obtained in Examples 1-5 in an acetonitrile solution of 0.1 M NaTFPB;

[0024] Figure 4 Water contact angle test results of X-Co-LDH and X-Co3S4 obtained in Examples 1-5;

[0025] Figure 5 Schematic diagram of the manufacturing process of the sensor chip and the reference electrode in the present invention;

[0026] Figure 6 Dynamic potential response curves and corresponding linear calibration curves; where a-b is Cu-Co3S4-Ca 2+ -ISM and Ca 2+ -ISM, c-d is Cu-Co3S4-Mg 2+ -ISM and Mg 2+ -ISM;

[0027] Figure 7 For Mn-Co3S4-Ca 2+ -ISM, Fe-Co3S4-Ca 2+ -ISM, Co3S4-Ca 2+ -ISM, Ni-Co3S4-Ca 2+ -ISM and Cu-Co3S4-Ca 2+ Chronopotentiometry curves of -ISM;

[0028] Figure 8 Potential detection curves of the sensing chip for 36 consecutive hours, where a is the potential detection curve of Cu-Co3S4-Ca 2+ -ISM and Cu-Co3S4-Mg 2+ -ISM, b is the potential detection curve of the prepared Ag / AgCl / PVB(NaCl) reference electrode;

[0029] Figure 9 Schematic diagram of the three-dimensional structure of the all-solid-state ion-selective sensing chip in the present invention;

[0030] Figure 10 Side sectional view of the all-solid-state ion-selective sensing chip in the present invention;

[0031] In the figure, 1 - the first encapsulation housing, 2 - the second encapsulation housing, 3 - the transduction layer, 4 - the ion-selective membrane, 5 - the wire. Detailed implementation mode

[0032] For the convenience of understanding the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0034] Any range recited in the present invention includes the end values, any value between the end values, and any sub-range constituted by any value between the end values or the end values.

[0035] Example 1

[0036] 0.5 mmol of Cu(NO3)2·3H2O, 1 mmol of Co(NO3)2·6H2O, 2.5 mmol of urea and 1 mmol of NH4F were added to 30 mL of deionized water. After stirring and dissolving until the solution was clear and transparent, it was poured into a Teflon liner and then sealed in a reaction kettle, and kept at a constant temperature of 130 °C for 5 h. The obtained product was alternately centrifuged and washed with ethanol and water, and denoted as Cu-Co-LDH. Subsequently, 0.25 g of Cu-Co-LDH was weighed and poured into 80 mL of 0.1 M Na2S aqueous solution. After stirring until evenly mixed, it was put into a Teflon liner and sealed in a reaction kettle, and reacted at a constant temperature of 120 °C for 6 h. The obtained product was Cu-Co3S4.

[0037] Example 2

[0038] 0.5 mmol of Co(NO3)2·6H2O, 1 mmol of Co(NO3)2·6H2O, 2.5 mmol of urea and 1 mmol of NH4F were added to 30 mL of deionized water. After stirring and dissolving until the solution was clear and transparent, it was poured into a Teflon liner and then sealed in a reaction kettle, and kept at a constant temperature of 130 °C for 5 h. The obtained product was alternately centrifuged and washed with ethanol and water, and denoted as intrinsic Co-LDH. Subsequently, 0.25 g of intrinsic Co-LDH was weighed and poured into 80 mL of 0.1 M Na2S aqueous solution. After stirring until evenly mixed, it was put into a Teflon liner and sealed in a reaction kettle, and reacted at a constant temperature of 120 °C for 6 h. The obtained product was Co3S4.

[0039] Example 3

[0040] 0.5 mmol of Mn(NO3)2·4H2O, 1 mmol of Co(NO3)2·6H2O, 2.5 mmol of urea and 1 mmol of NH4F were added to 30 mL of deionized water. After stirring and dissolving until the solution was transparent and clear, it was poured into a Teflon inner liner and then sealed in a reaction kettle. It was kept at a constant temperature of 130 °C for 5 h. The obtained product was alternately centrifuged and washed with ethanol and water, denoted as Mn-Co-LDH. Subsequently, 0.25 g of Mn-Co-LDH was weighed and poured into 80 mL of 0.1 M Na2S aqueous solution. After stirring until evenly mixed, it was placed in a Teflon inner liner, sealed in a reaction kettle, and reacted at a constant temperature of 120 °C for 6 h. The obtained product was Mn-Co3S4.

[0041] Example 4

[0042] 0.5 mmol of Fe(NO3)3·9H2O, 1 mmol of Co(NO3)2·6H2O, 2.5 mmol of urea and 1 mmol of NH4F were added to 30 mL of deionized water. After stirring and dissolving until the solution was transparent and clear, it was poured into a Teflon inner liner and then sealed in a reaction kettle. It was kept at a constant temperature of 130 °C for 5 h. The obtained product was alternately centrifuged and washed with ethanol and water, denoted as Fe-Co-LDH. Subsequently, 0.25 g of Fe-Co-LDH was weighed and poured into 80 mL of 0.1 M Na2S aqueous solution. After stirring until evenly mixed, it was placed in a Teflon inner liner, sealed in a reaction kettle, and reacted at a constant temperature of 120 °C for 6 h. The obtained product was Fe-Co3S4.

[0043] Example 5

[0044] 0.5 mmol of Ni(NO3)2·6H2O, 1 mmol of Co(NO3)2·6H2O, 2.5 mmol of urea and 1 mmol of NH4F were added to 30 mL of deionized water. After stirring and dissolving until the solution was transparent and clear, it was poured into a Teflon inner liner and then sealed in a reaction kettle. It was kept at a constant temperature of 130 °C for 5 h. The obtained product was alternately centrifuged and washed with ethanol and water, denoted as Ni-Co-LDH. Subsequently, 0.25 g of Ni-Co-LDH was weighed and poured into 80 mL of 0.1 M Na2S aqueous solution. After stirring until evenly mixed, it was placed in a Teflon inner liner, sealed in a reaction kettle, and reacted at a constant temperature of 120 °C for 6 h. The obtained product was Ni-Co3S4.

[0045] Figure 1 Scanning electron microscope photographs of X-doped cobalt double hydroxides (X-Co-LDH, X = Mn, Fe, Co, Ni or Cu), from Figure 1It can be seen that the sea urchin plush-like X-doped cobalt double hydroxide (X-Co-LDH, X = Mn, Fe, Co, Ni or Cu) nanoflower precursor composed of nanoneedles with a diameter of about 50 nm allows for the thorough progress of the subsequent sulfidation reaction, and a larger specific surface area can be constructed during the subsequent process. Subsequently, under the action of S 2- ion etching, the original X-doped cobalt trisulfide (X-Co3S4, X = Mn, Fe, Co, Ni or Cu) all maintained the sea urchin nanoflower-like morphology approximately matching the original diameter of the X-Co-LDH precursor, and rich micro / nano structures were carved on the surface of the nanoneedles. Among them, the Co3S4 nanoflower needles were severely broken and showed a thin-layered shape. The morphologies of the Mn-Co3S4, Ni-Co3S4, and Cu-Co3S4 nanoflowers after element doping were well maintained, while there was partial needle adhesion in the Fe-Co3S4 nanoflower.

[0046] Figure 2 Scanning electron microscope photographs of X-doped cobalt trisulfide (X-Co3S4, X = Mn, Fe, Co, Ni or Cu), from Figure 2 It can be seen that under the action of S 2- ion etching, X-Co3S4 all maintained the precursor morphology and the surface was rich in surface micro / nano structures. There was partial needle adhesion in Fe-Co3S4, and the morphologies of Mn-Co3S4, Ni-Co3S4, and Cu-Co3S4 were maintained. The Co3S4 needles were severely broken and showed a thin-layered shape. This indicates that the introduction of the second metal ion (i.e., transition metal X) strengthened the structure of the cobalt double hydroxide matrix, effectively preventing structure collapse and damage. The rich surface micro / nano structures bring potential surface hydrophobic ability, and the more excellent structural stability after the introduction of the second metal may provide a guarantee for the subsequent development of stable interfaces.

[0047] Test examples

[0048] 1. Capacitance test

[0049] Using a glassy carbon electrode as the working electrode, Ag / AgCl as the reference electrode to form a three-electrode system, and a platinum wire electrode as the counter electrode, the test was carried out in 0.1 M KCl, and the scanning rate was 0.1 V·s -1 , and the potential range was -0.5 V to +0.5 V. The capacitance of the materials X-Co3S4 (X = Mn, Fe, Co, Ni or Cu) obtained in Examples 1-5 was measured by the integral area of the CV curve, and the test results are shown in Figure 3 .

[0050] Figure 3The results show that the CV integral area in the acetonitrile solution of 0.1 M NaTFPB follows the order: Cu-Co3S4 (10.77) > Ni-Co3S4 (8.57) > Fe-Co3S4 (8.11) > Mn-Co3S4 (7.71) > Co3S4 (7.46). Among them, Cu-Co3S4 shows an obvious redox pseudocapacitance process and has the best capacitance.

[0051] 2. Hydrophobicity test

[0052] Using a DSAHT17C high-temperature contact angle measuring instrument, the sessile drop method was used to measure the contact angle of water droplets on the surface of the X-Co-LDH (X = Mn, Fe, Co, Ni or Cu) ion-selective membranes obtained in Examples 1-5. The test results are shown in Figure 4 , and it can be seen that X-Co-LDH exhibits high hydrophobicity due to its surface hierarchical micro-nano structure. Under the hydrophobic regulation of the micro / nano hierarchical surface structure, the hydrophobic water contact angle follows the order: Mn-Co3S4 (118.96°) > Ni-Co3S4 (105.11°) > Fe-Co3S4 (99.70°) > Cu-Co3S4 (99.52°) > Co3S4 (94.75°).

[0053] Ion-selective membranes - calcium ion-selective membrane (Ca 2+ -ISM) and magnesium ion-selective membrane (Mg 2+ -ISM) were prepared as follows:

[0054] 1.3 wt% calcium ionophore II (ETH129), 0.6 wt% NaTFPB, 65.4 wt% o-NPOE, and 32.7 wt% PVC, a total of 300 mg, were dissolved in 3 mL of THF to obtain a calcium ion-selective membrane solution; 1.03 wt% magnesium ionophore VI (ETH5506), 0.76 wt% NaTFPB, 67.28 wt% o-NPOE, and 30.93 wt% PVC, a total of 300 mg, were dissolved in 3 mL of THF to obtain a magnesium ion-selective membrane solution.

[0055] 3. Dynamic potential response test

[0056] According to Figure 5The reference electrode is fabricated according to the process shown below: Customize a silver cylinder with a purity of 99.9% (bottom radius 1.5 mm, height 2.5 mm). Press the silver cylinder into the mold (large) with the wire already welded to prevent other elements from being introduced onto the surface of the silver cylinder during the wire welding process. Subsequently, 20 μL of 0.1 M FeCl3 solution is pipetted onto the surface of the silver cylinder and chlorinated for 60 s, and then the surface is rinsed with deionized water to prepare the Ag / AgCl layer on the surface. Finally, 10 μL of the Buvon polymer solution filled with NaCl and PVB is dropped onto the surface of the Ag / AgCl layer, and after drying in the fume hood for 12 h, it is ready for use.

[0057] According to Figure 5 For the indicator electrode of the sensing chip mass-produced according to the preparation process shown below, first, customize a copper mold (small) with a surface gold plating, a bottom radius of 1.5 mm and a height of 2.5 mm, and a copper mold (large) with a surface gold plating, a bottom radius of 1.75 mm, a height of 2.8 mm, and an internal depth of 2.5 mm. Weld a wire with an insulating layer on the surface at the bottom of the mold (large), with a welding temperature of 280 °C and a duration of 1 s. Grind X-Co3S4 and PVDF in a mass ratio of 1:5 to mix them evenly to obtain a mixed black powder. Weigh 20 mg of the mixed black powder and pour it into the mold (small). After applying a pressure of 5 MPa for 10 s, it is taken out after molding. Subsequently, the molded material is pressed into the mold (large) with the wire already welded to prevent material denaturation caused by high temperature during the wire welding process. Pipette 30 μL of the calcium ion selective membrane solution onto the top of the pressed sheet layer, and after placing it in the fume hood for 12 h to dry, the all-solid-state ion selective sensing chip X-Co3S4-Ca 2+ -ISM (X = Mn, Fe, Co, Ni or Cu); Pipette 30 μL of the magnesium ion selective membrane solution onto the top of the pressed sheet layer, and after placing it in the fume hood for 12 h to dry, the all-solid-state ion selective sensing chip X-Co3S4-Mg 2+ -ISM (X = Mn, Fe, Co, Ni or Cu).

[0058] The obtained sensing chip structure is as shown in Figure 9 and 10 shown below. The sensing chip includes a first encapsulation housing 1, a second encapsulation housing 2 nested in the first encapsulation housing 1, a wire 5 connected to the outer wall of the second encapsulation housing 2, a transduction layer 3 provided in the second encapsulation housing 1, and an ion selective membrane 4 provided on the surface of the transduction layer 3; wherein, the transduction layer 4 is made of a mixture of the all-solid-state ion selective sensing chip material and PVDF in a mass ratio of 1:5.

[0059] Use the open circuit potential test method to respectively test Cu-Co3S4-Ca 2+ -ISM and Cu-Co3S4-Mg 2+-ISM was used to conduct dynamic potential response tests, and the test results are shown in Figure 6 , it can be seen that Cu-Co3S4-Ca 2+ -ISM and Cu-Co3S4-Mg 2+ -ISM's dynamic potential response curves and the corresponding linear calibration curves showed near-Nernstian linear dynamic potential responses of 28.98 ± 1.66 (1.01×10 -1 -10 -6 M with R -7 = 0.999) and 27.99 ± 2.07 mV·dec 2 (2.27×10 -1 M with R -7 = 0.998) ([Fig. 2 a-b). For the directly coated ion-selective membrane Ca Figure 6 -ISM and Mg 2+ -ISM, the dynamic potential response curves and the corresponding linear calibration curves showed near-Nernstian linear dynamic potential responses of 28.50 ± 4.08 (4.27×10 2+ M with R -6 = 0.999) and 27.82 ± 1.29 mV·dec 2 (8.12×10 -1 M with R -6 = 0.993) ([Fig. 2 c-d). Figure 6

[0060] 4. Sensing Chip Interface Capacitance Test

[0061] As Figure 7 shown, by applying a current of ±1 nA at the interface and calculating according to I / C = ΔE / Δt (I = ±1 nA), the interface capacitance law showed that Ca 2+ -ISE (247.02 ± 1.99 μV·s -1 , n = 3, 4.05 μF) > Co3S4-Ca 2+ -ISE (96.16 ± 0.84 μV·s -1 , n = 3, 103.99 μF) > Mn-Co3S4-Ca 2+ -ISE (29.87 ± 0.36 μV·s -1 , n = 3, 33.47 μF) > Fe-Co3S4-Ca 2+ -ISE (10.93 ± 0.21 μV·s -1 , n = 3, 91.42 μF) > Ni-Co3S4-Ca 2+ -ISE (3.37 ± 0.04 μV·s -1, n = 3, 297.71 μF) > Cu - Co3S4 - Ca 2+ -ISE(1.76 ± 0.01 μV·s -1 , n = 3, 598.18 μF). Therefore, the introduction of Cu - Co3S4 results in a best short - term potential drift of 1.76 ± 0.01 μV·s -1 and an extremely high interfacial capacitance of approximately 568.18 μF, which greatly promotes the ion - electron transduction at the interface.

[0062] 5. Long - term stability test of the sensing chip

[0063] Figure 8 The continuous test results of potential stability for 36 h are shown. The Cu - Co3S4 - Ca 2+ -ISM, Cu - Co3S4 - Mg 2+ -ISM and Ag / AgCl / PVB(NaCl) have potential offset changes of 4.75 ± 0.04, 3.88 ± 0.08 and 4.39 ± 0.02 μV·h -1 respectively, revealing the excellent long - term usability of the developed batch - fabricable sensing chips. The broadened detection range, lower short - term potential drift and 36 - h long - term potential stability show that the introduction of hydrophobic Cu - Co3S4 stabilizes the electrode potential.

[0064] Although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0065] Therefore, the above - mentioned are only the preferred embodiments of this application, not used to limit the scope of implementation of this application; that is, all equivalent transformations made according to the scope of the claims of this application are within the protection scope of the claims of this application.

Claims

1. A material for an all-solid-state ion-selective sensing chip, characterized in that, It is composed of hydrophobic transition metal cobalt sulfide; the transition metal X is at least one of Mn, Fe, Co, Ni, and Cu.

2. The preparation method of the all-solid-state ion-selective sensing chip material according to claim 1, characterized in that, It includes the following steps: S1. Add the soluble salt of transition metal X, the soluble salt of Co, the alkaline precipitating agent, and NH4F into deionized water. After stirring until it becomes clear, transfer it into a reaction kettle and react at 100 - 150 °C under sealed conditions for 4 - 6 h. Filter to obtain the solid product X-Co-LDH. S2. After uniformly stirring the solid product X-Co-LDH with the aqueous solution of sulfur source, transfer it into a reaction kettle and react at 100 - 140 °C under sealed conditions for 5 - 7 h to obtain the solid product X-Co3S4, that is, the hydrophobic transition metal sulfide.

3. The preparation method according to claim 2, wherein In step S1, the soluble salt of transition metal X is the nitrate of X; the soluble salt of Co is Co(NO3)2·6H2O; the alkaline precipitating agent is urea; the aqueous solution of sulfur source is 0.1 M Na2S aqueous solution.

4. The preparation method according to claim 2, characterized in that, In step S1, the molar ratio of the soluble salt of transition metal X, the soluble salt of Co, urea, and NH4F is (0 - 1):2:(5 - 20):(1 - 8).

5. The preparation method according to claim 2, wherein, In step S2, the molar ratio of the solution X-Co-LDH to the aqueous solution of sulfur source is (3 - 8):

9.

6. A all-solid-state ion selective sensing chip, characterized in that, It includes a first encapsulation housing, a second encapsulation housing nested in the first encapsulation housing, a transduction layer provided in the second encapsulation housing, and an ion-selective membrane provided on the surface of the transduction layer; wherein, the transduction layer is made by mixing the all-solid-state ion-selective sensing chip material described in claim 1 with PVDF.

7. The all-solid-state ion-selective sensing chip according to claim 6, characterized in that, The mass ratio of the all-solid-state ion-selective sensing chip material to PVDF is 1:(1 - 10).

8. A all-solid-state ion-selective electrode, characterized in that, It uses the all-solid-state ion-selective sensing chip material prepared by the preparation method described in any one of claims 2 - 5 as the transduction layer.

9. Use of an all-solid-state ion-selective electrode as described in claim 8, characterized in that, The detection of the cation concentration in the environment.

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