RuO2.xH2O / GP composite material and preparation method and application thereof

Abstract

The invention provides a RuO2.xH2O / GP-based composite material as well as a preparation method and application of the RuO2.xH2O / GP-based composite material. The composite material comprises the following raw material components: ruthenium dioxide hydrate, graphite powder and epoxy resin glue, wherein the mass ratio of the ruthenium dioxide hydrate to the graphite powder is (2-3.5): 1; based on the mass of the graphite powder, the dosage of the epoxy resin glue is 1-3ml / g. The novel metal oxide composite type pH sensitive electrode has remarkable advantages, and the excellent machinability enables the novel metal oxide composite type pH sensitive electrode to be adaptive to various sensor frameworks; good shape plasticity allows the composite material to be prepared into various physical shapes; meanwhile, the method has the advantages of convenience in operation and cost effectiveness, and an ideal sensitive material selection is provided for pH sensing application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite materials, in particular to a RuO2·xH2O / GP composite material and a preparation method and use thereof. BACKGROUND

[0002] Metal oxides (MO x ) have attracted considerable attention due to their broad application prospects in electrochemistry, biomedicine, and energy and environmental science. These materials have excellent electrical properties, tunable electrochemical activity, and good biocompatibility, which together contribute to their key role in the manufacture of high-performance chemical sensors. Benefiting from their high specific surface area structure, MO x can provide abundant active sites, thereby significantly improving the sensitivity, selectivity, and catalytic efficiency of sensors, and facilitating high-precision detection of specific analytes. In addition, MO x materials also exhibit excellent environmental stability and long service life, and can achieve rapid response under complex conditions, and are therefore widely considered as ideal candidate materials for the next generation of sensing networks and real-time online monitoring systems.

[0003] Among numerous application directions, electrochemical pH sensors are one of the most representative applications of MO x materials, and are widely used in the fields of biological fluid detection, environmental water quality monitoring, and chemical process control. However, such sensors still face significant challenges in actual promotion. For example, the preparation process is usually complex and tedious, often involving multiple key steps such as sol-gel, hydrothermal synthesis, high-temperature annealing, and electrode modification, which is time-consuming and requires high repeatability control. At the same time, the high purity of the precursors used in the preparation process and the harsh process conditions also result in high production costs. These factors seriously restrict the large-scale production and actual commercial application of MO x -based pH sensors, and therefore the development of low-cost, high-throughput preparation techniques has become a key problem that needs to be broken through in this field. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a RuO2·xH2O / GP composite material and a preparation method and use thereof, to solve the problems of high purity requirement of raw materials, harsh process conditions, and high production cost of sensing materials for electrochemical pH sensors in the prior art.

[0005] To achieve the above-mentioned objects and other related objects, the present application is implemented by including the following technical solutions.

[0006] In the present application, the applicant constructs a composite material based on RuO2.xH2O / GP for a pH-sensitive electrode, which can be used for pH detection by applying only a simple tabletting process to press the electrode into a cylindrical shape. Electrochemical tests show that, under the condition of 25℃, the sensor exhibits excellent potential response characteristics in the pH range of 1-12, with a sensitivity reaching the theoretical value (50 mV / pH, R2=0.996), and can realize real-time monitoring. The new metal oxide composite pH-sensitive electrode has obvious advantages, excellent processability enables it to adapt to various sensor architectures; good morphological plasticity allows it to be prepared into various physical forms; and at the same time, it has the advantages of convenient operation and cost-effectiveness, providing an ideal sensitive material selection for pH sensing applications.

[0007] The first aspect of the present application provides a RuO2·xH2O / GP composite material, the raw material components of the composite material comprising:

[0008] Ruthenium oxide hydrate, graphite powder and epoxy resin glue; wherein the mass ratio of ruthenium oxide hydrate to graphite powder is (2-3.5):1;

[0009] The amount of the epoxy resin glue is 1-3 ml / g based on the mass of the graphite powder.

[0010] Preferably, the mass ratio of ruthenium oxide hydrate to graphite powder is 2:1, 2.5:1, 3:1 or 3.5:1.

[0011] Preferably, the amount of the epoxy resin glue is 1-3 ml / g based on the mass of the graphite powder, such as 1 ml / g, 1.25 ml / g, 1.5 ml / g, 1.75 ml / g, 2 ml / g, 2.25 ml / g, 2.5 ml / g or 3 ml / g.

[0012] Preferably, the mesh number of the graphite powder is 300-5000 mesh, such as 300 mesh, 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh, 1000 mesh, 1100 mesh, 1200 mesh, 1300 mesh, 1400 mesh, 1500 mesh, 1600 mesh, 1800 mesh, 2000 mesh, 2500 mesh, 3000 mesh, 3500 mesh, 4000 mesh, 4500 mesh or 5000 mesh.

[0013] Preferably, the ruthenium oxide hydrate is in the form of powder, and the particle size thereof is not more than 10 μm. More preferably, the particle size of the graphite powder is not more than 5 μm.

[0014] Preferably, the ruthenium dioxide is ruthenium dioxide hydrate. In actual research and development, the applicant found that the electrode formed by pressing the non-hydrated ruthenium dioxide has a large difference in Nernst response value from the theoretical value.

[0015] Preferably, the epoxy resin glue comprises an epoxy resin composition and a curing agent, wherein the mass ratio of the epoxy resin composition to the curing agent is 1:(0.3-1.2), such as 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2.

[0016] The epoxy resin composition described in the present application is preferably a medium hardness epoxy resin composition. In a preferred embodiment, the epoxy resin composition comprises the following ingredients by weight:

[0017]

[0018] Preferably, the 2,2'-[(1-methylethylidene)bis(4,1-phenyleneformaldehyde)] bisoxirane can be 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight or 75 parts by weight. More preferably, the 2,2'-[(1-methylethylidene)bis(4,1-phenyleneformaldehyde)] bisoxirane is 55-65 parts by weight.

[0019] Preferably, the phenolic epoxy resin can be 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight and 30 parts by weight.

[0020] Preferably, the 1,6-ethanediol is 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight.

[0021] Preferably, the 3-(trimethoxysilyl)-1-propanethiol can be 0 parts, or 0.1 parts, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight and 1 parts by weight.

[0022] Preferably, the phenolic epoxy resin is an epoxy resin of type F-44.

[0023] Preferably, the curing agent comprises 3-aminomethyl-3, 5, 5-trimethylcyclohexylamine and benzyl alcohol, wherein the mass ratio of 3-aminomethyl-3, 5, 5-trimethylcyclohexylamine and benzyl alcohol is 0.5-2:1. Such as can be 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1. More preferably, the mass ratio of 3-aminomethyl-3, 5, 5-trimethylcyclohexylamine and benzyl alcohol is 1-2:1.

[0024] The second aspect of the present application also provides a processing forming method of the composite material as described above, comprising the following steps: mixing RuO2.xH2O, graphite powder and epoxy resin glue;

[0025] Then, after preforming, heat treatment is performed. Preferably, further performing the step of pressing forming is included.

[0026] Preferably, preforming and further pressing forming can be performed in a tablet press.

[0027] Preferably, the pressure of preforming and further pressing forming is 8-16 MPa, such as can be 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa. Further, the pressure of preforming is not higher than the pressure of further pressing forming.

[0028] More preferably, the pressure treatment time of preforming and further pressing forming is 5-20 minutes.

[0029] The above-mentioned heat treatment is to promote the better adhesion and curing forming of the epoxy resin glue and the ruthenium dioxide hydrate and graphite powder. The temperature of heat treatment is 35-120℃, and the heat treatment time is 40-120 min. Gradient temperature treatment can be performed, or gradient temperature treatment and gradient temperature reduction treatment can be performed, and the treatment time under each gradient is 8-15 minutes.

[0030] Further preferably, after mixing RuO2.xH2O, graphite powder and epoxy resin glue, the mixture is first pressed to preform in a tablet press, and then heat treatment is performed at several gradient temperatures between 35-110℃, first increasing the temperature and then reducing the temperature, and the heat treatment time is 40-60 min; then further pressing forming is performed under 10-15 MPa. Still further preferably, the heat treatment at gradient temperature includes 8-12 min treatment at 30-40℃, 65-75℃, 100-110℃, respectively.

[0031] More preferably, when pressing forming is performed, vacuumizing operation is performed.

[0032] RuO2·xH2O can inhibit the accumulation of space charge due to its chemical stability and high conductivity. This feature makes the electrode pH response speed better than the aforementioned oxides. Its pH detection principle is that the metal oxide (represented as MO x ) will undergo a hydrolysis reaction on its surface when in contact with an aqueous solution, forming a layer of hydroxylated surface (M-OH). This layer of surface functional groups is called surface hydroxyl sites. These sites can undergo protonation or deprotonation reactions like polybasic acids, depending on the pH of the solution, thereby carrying a charge: in acidic solutions (high H + concentration): The oxide surface gains protons and carries a positive charge. In basic solutions (low H + concentration): The oxide surface loses protons and carries a negative charge.

[0033] Graphite has become an extremely attractive candidate material in the field of electrochemical sensors due to its excellent electrical conductivity, good chemical stability, and high cost-effectiveness. Its inherent porous structure and large specific surface area not only facilitate efficient electron transport but also enable high loading of active materials. When mixed with metal oxide powders such as RuO2·xH2O, graphite can form a continuous conductive network, significantly improving the sensitivity of the sensor. Although pure RuO2·xH2O powder is difficult to directly form, graphite powder has good lubricity and plasticity, which can effectively improve the processing performance of the material. In addition, graphite also exhibits excellent mechanical strength and excellent corrosion resistance, which can ensure the long-term stable operation of the sensor under diverse environmental conditions.

[0034] The third aspect of the present application also discloses the use of the composite material as described above as a pH sensing element.

[0035] Preferably, the pH sensing element includes a pH sensor, a pH sensing electrode, etc.

[0036] Preferably, the pH sensing element formed by the composite material has good potential response characteristics in the pH range of 1-12, and its sensitivity can reach the theoretical value of 50 mV / pH (R2=0.996). It can be conveniently used in electrochemical detection.

[0037] According to the process of press molding, the specific shape or structure of the pH sensing element can be determined by a specific mold. It can be cylindrical, round, square, spherical, prismatic, etc., or irregular shape to match specific application scenarios.

[0038] As described above, the RuO2·xH2O / GP composite material, its preparation method and use of the present application have the following beneficial effects:

[0039] 1. Metal oxides are important sensitive materials in pH detection, but the scarcity and high cost of ruthenium in RuO2·xH2O, a platinum group metal, limit its practical application. In contrast, graphite powder is chemically stable, readily available, has a simple preparation process, low cost, and good storage stability. Composite materials based on RuO2·xH2O and graphite powder (GP) can overcome the problems of high cost and difficult processing.

[0040] 2. The pH sensor constructed based on RuO2·xH2O / graphite powder composite material exhibits excellent detection performance, has a wide pH detection range, and conforms to the Nernst response theory.

[0041] 3. This composite material can be prepared for pH detection using only a tableting process, which is simple and efficient.

[0042] 4. Its excellent processability allows it to be adapted to a variety of sensor structures; its good morphological plasticity allows it to be processed into a variety of physical forms; at the same time, it has the advantages of easy operation and cost-effectiveness, making it an ideal sensitive material choice for pH sensing applications. Attached Figure Description

[0043] Figure 1 The image shown is a photograph of the pH electrode obtained in Example 1 of this invention.

[0044] Figure 2 Tables (a) and (b) show the pH electrical response curves and linear calibration curves of the composite materials constructed with graphite powder of different mesh sizes in Example 1 of this invention. (1:3)

[0045] Figure 2 Figures (c) and (d) show the pH electrical response curve and linear calibration curve of the composite material formed by different raw material mass ratios in Example 2 of the present invention.

[0046] Figure 3 The pH electrical response curve and linear calibration curve of the composite material formed in Example 3 are shown.

[0047] Figure 4 The figures show the pH electrical response curve and linear calibration curve of the composite material formed using non-ruthenium dioxide hydrate in Comparative Example 1. Detailed Implementation

[0048] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] Various raw materials and reagents were purchased from commercial suppliers and used without further purification unless otherwise stated. Raw materials and reagents susceptible to moisture were stored in airtight bottles and used directly without special treatment.

[0050] The composition of the composite material in the present application needs to be mixed when used. In order to facilitate uniform mixing, the type of stirring is not particularly limited, for example, it can be mechanical stirring, i.e. stirring under the action of mechanical force.

[0051] The hydrate ruthenium dioxide in the present application is a hydrate of ruthenium dioxide.

[0052] The epoxy resin glue used in the examples is SpeciFix-40. The product itself includes a resin composition and a curing agent. In use, the pH value electrical response curve and the linear calibration curve are calculated according to the pH value electrical response curve. The resin composition and the curing agent are used in a ratio of 1:1.

[0053] In the following examples, a hand press (YLJ-40T-SJ) was used as the tablet press, and a cylindrical die was used as the tablet press die; a Gramy (Reference 6000) workstation was used; a two-electrode system was used, and the reference electrode was Ag / AgCl. The open circuit potential method was used to obtain the corresponding electrical response curve and calculate the linear calibration curve. The test object was a standard solution with a pH of 1-12, which was prepared according to HG-23676-2008. The test temperature was 25°C.

[0054] Example 1

[0055] In the present specific example, the RuO2·xH2O / GP composite material, the raw material components of the composite material include:

[0056] Ruthenium dioxide hydrate, graphite powder and epoxy resin glue;

[0057] The mass ratio of the ruthenium dioxide hydrate to the graphite powder is 2:1.

[0058] The amount of the epoxy resin glue is 1.75 ml / g based on the mass of the graphite powder.

[0059] The mesh number of the graphite powder is 325 mesh, 3000 mesh and 10000 mesh, respectively.

[0060] Tablet forming method: after mixing, the mixture was placed in a tablet press to be pre-formed (without pressure), then heated at 105°C for 30 min, and finally further pressed in the tablet press at 10 MPa for 10 min to form.

[0061] The electrical response curve and linear calibration curve obtained by testing are shown in Figs. 3(a) and 3(b). Figure 2 As shown in Figs. 3(a) and 3(b), the curves of 325 mesh and 3000 mesh are more consistent with the theoretical values, and the curve of 3000 mesh is better. The test curve of the electrode formed by 10000 mesh graphite has deviated from the theoretical value, and the Nernst response value is poor.

[0062] Example 2

[0063] In the specific embodiment, the raw material components of the RuO2·xH2O / GP composite material include:

[0064] Ruthenium dioxide hydrate, graphite powder and epoxy resin glue;

[0065] The mass ratio of the ruthenium dioxide hydrate to the graphite powder is 2:1, 3:1 or 4:1, respectively.

[0066] The amount of the epoxy resin glue is 1.75 ml / g based on the mass of the graphite powder.

[0067] The mesh number of the graphite powder is 3000.

[0068] The tablet forming method is as follows: after mixing, the mixture is put into a tablet press to be pre-formed (without pressure), then heated at 105°C for 30 min, and finally further pressed in the tablet press at 10 MPa for 10 min to be formed.

[0069] The electrical response curve and linear calibration curve obtained by testing are shown in Figs. 3(a) and 3(b). Figure 2 As shown in Figs. 3(c) and 3(d), the curve of the 4:1 ratio has deviated.

[0070] Example 3

[0071] In the specific embodiment, the raw material components of the RuO2·xH2O / GP composite material include:

[0072] Ruthenium dioxide hydrate, graphite powder and epoxy resin glue;

[0073] The mass ratio of the ruthenium dioxide hydrate to the graphite powder is 3:1.

[0074] The amount of the epoxy resin glue is 1.75 ml / g based on the mass of the graphite powder.

[0075] The mesh number of the graphite powder is 3000.

[0076] The tablet forming method in the embodiment is more detailed, which is as follows:

[0077] After mixing, the mixture is placed in a tablet press, vacuumed, and then pressed into a preform at 10 MPa.

[0078] The reheating treatment specifically involved gradient heating (35℃; 70℃; 105℃) followed by gradient cooling (105℃; 70℃; 35℃), with each temperature lasting 10 minutes.

[0079] Finally, the tablets were further compressed in a tablet press at 10 MPa for 10 min and then at 15 MPa for 10 min.

[0080] The electrical response curve and linear calibration curve obtained from this are as follows: Figure 3 As shown, by Figure 3 It can be seen that the obtained electrical response curve and linear calibration curve are very close to the theoretical values.

[0081] Comparative Example 1

[0082] Instead of using ruthenium oxide hydrate, non-ruthenium oxide hydrate, i.e., ruthenium dioxide, is used.

[0083] In this specific embodiment, the RuO2 / GP composite material comprises the following raw material components:

[0084] Ruthenium dioxide, graphite powder, and epoxy resin adhesive;

[0085] The mass ratio of ruthenium dioxide to graphite powder is 2:1.

[0086] Based on the mass of graphite powder, the amount of epoxy resin adhesive used is 1.75 ml / g.

[0087] The graphite powder has a mesh size of 3000.

[0088] Tableting method: After mixing, the mixture is placed in a tablet press and pre-formed (without pressure), then heated at 105℃ for 30 minutes, and finally further pressed in a tablet press at 10MPa for 10 minutes to form the final product.

[0089] The electrical response curve and linear calibration curve obtained from the test are as follows: Figure 4 As shown, by Figure 4 It can be seen that the electrode materials obtained using non-ruthenium dioxide hydrate (ruthenium dioxide) have poor performance.

[0090] The electrode formed by pressing ruthenium oxide hydrate and graphite powder of a specific mesh size into sheets using epoxy resin, as described in this application, not only exhibits good molding and processing performance but also demonstrates excellent pH sensitivity in the final electrode material, showing a favorable electrical response curve within the range of 1 to 12. Therefore, this invention effectively overcomes the various shortcomings of the prior art and possesses high industrial applicability.

[0091] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A RuO2·xH2O / GP composite material, characterized in that, The raw material components of the composite material include: Ruthenium oxide hydrate, graphite powder, and epoxy resin adhesive; wherein the mass ratio of ruthenium oxide hydrate to graphite powder is (2-3.5):1; and the amount of epoxy resin adhesive used is 1-3 ml / g based on the mass of graphite powder.

2. The composite material according to claim 1, characterized in that, Includes one or more of the following features: The graphite powder has a particle size of 300-5000 mesh; The ruthenium oxide hydrate is in powder form with a particle size not exceeding 10 μm; The epoxy resin adhesive comprises an epoxy resin composition and a curing agent, wherein the mass ratio of the epoxy resin composition to the curing agent is 1:(0.3-1.2). The epoxy resin adhesive is a medium-hardness epoxy resin adhesive.

3. The composite material according to claim 2, characterized in that, The epoxy resin composition comprises the following components in parts by weight:

4. The composite material according to claim 3, characterized in that, The phenolic epoxy resin is type F-44 epoxy resin.

5. The composite material according to claim 2, characterized in that, The curing agent comprises 3-aminomethyl-3,5,5-trimethylcyclohexylamine and benzyl alcohol, wherein the mass ratio of 3-aminomethyl-3,5,5-trimethylcyclohexylamine to benzyl alcohol is 0.5 to 2:

1.

6. A method for processing and molding the composite material as described in any one of claims 1 to 5, characterized in that, The process includes the following steps: mixing ruthenium oxide hydrate, graphite powder and epoxy resin, then pressing and preforming the mixture, followed by heat treatment; preferably, it also includes further pressing and molding.

7. The processing and molding method for composite materials according to claim 6, characterized in that, Includes one or more of the following features: Pre-forming and further compression molding are carried out in a tablet press; The pressure for preforming and further compression molding is 8–16 MPa; The pressure of preforming should not be higher than the pressure of further pressing. The pressure treatment time for preforming and further pressing is 5 to 20 minutes; The heat treatment temperature is 35–120℃, and the heat treatment time is 40–120 min; During the pressing and molding process, a vacuuming operation is performed.

8. The processing and forming method according to claim 7, characterized in that, Ruthenium oxide hydrate, graphite powder and epoxy resin are mixed and then pressed in a tablet press for pre-forming. Then, the tablets are subjected to heat treatment at several temperature gradients between 35 and 110°C, with the temperature first rising and then falling for 40 to 60 minutes. Finally, the tablets are pressed into shape at 10 to 15 MPa.

9. The processing and forming method according to claim 8, characterized in that, The heat treatment under gradient temperatures includes treatments at 30–40℃, 65–75℃, and 100–110℃ for 8–12 minutes each.

10. Use of a composite material as described in any one of claims 1 to 5 as a pH sensing element.

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