CN112501631B

CN112501631B - Noble metal rhodium hydrogen evolution electrocatalyst and application

Info

Publication number: CN112501631B
Application number: CN202011099380.0A
Authority: CN
Inventors: 杨植; 郑仙诺; 陈倩倩; 张潇栋; 金玉威; 周学梅
Original assignee: Wenzhou University
Current assignee: Wenzhou University
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2022-01-04
Anticipated expiration: 2040-10-14
Also published as: CN112501631A

Abstract

The invention belongs to the field of electrolytic water hydrogen evolution catalytic materials, and particularly relates to a noble metal rhodium hydrogen evolution electrocatalyst and application thereof. The rhodium oxide-nickel-based phosphate-carbon carrier is prepared by the two-step electrodeposition mild synthesis method, and has low Rh content. Electrochemical experimental results show that the rhodium oxide-nickel based phosphate-carbon carrier shows excellent HER electrochemical performance, which can be compared with the performance of commercial Pt/C catalyst.

Description

Noble metal rhodium hydrogen evolution electrocatalyst and application

Technical Field

The invention belongs to the field of electrolytic water hydrogen evolution catalytic materials, and particularly relates to a noble metal rhodium hydrogen evolution electrocatalyst and application thereof.

Background

The environmental consequences of fossil fuel consumption and carbon dioxide emissions have forced significant efforts to develop new renewable materials of sufficient size to replace fossil fuels and meet the ever-increasing global energy consumption needs. The development of an effective production strategy for synthesizing molecular hydrogen into a hot tide. With the aid of highly active non-noble metal electrocatalysts, electrolyzed water is becoming a promising candidate for producing low cost, high purity hydrogen. Theoretically described gibbs free energy dependence (ag) for hydrogen adsorption_H) Typically associated with catalyst activity. Today, platinum (Pt) and its alloys have Δ G close to 0_HIt has high exchange current density and lowest Tafel slope under acidic condition, so it is considered as a superior catalyst in HER. Despite the above advantages, platinum HER catalysts have greatly limited large-scale commercial applications due to the scarcity of Pt, high price, and poor stability. Recently, several studies have demonstrated that other noble metals can also exhibit excellent HER performance, such as palladium (Pd), iridium (Ir), rhodium (Rh), and ruthenium (Ru), among others. Since noble metals are expensive, it is crucial to reduce their use in HERIn (1). But at the same time, in order to ensure the high activity of the noble metal, the compound of the noble metal and the transition metal is expected to obtain the HER electrocatalyst with high efficiency and low cost. .

Metal rhodium (Rh) exhibits excellent activity in various applications. In particular, rhodium phosphide (Rh-P) catalysts exhibit excellent HER performance and good cycle stability. Introduction of P into Rh catalyst material results in Δ G_H*Shifting to a more neutral value (closer to zero) indicates that decreasing Rh loading results in greater catalytic activity. Density functional theory calculations (DFT) indicate that the open shell effect of the P3P band not only promotes Rh 4d proton-electron charge exchange, but also provides excellent P-P overlap, which may be beneficial to the HER process in alkaline media. Effect of phosphorus (P) on HER activity, a strategy to further improve TMP catalytic efficiency and stability, mainly by structural engineering. The Fan topic group obtains Rh with small size, monodispersity and uniform distribution by a calcination method_xThe P nanoparticles are supported on phosphorus doped carbon nitride. An electrode with highly Rh-dense surface has high HER intrinsic activity in an acid electrolyte. However, as known from the literature reported at the present stage, the synthesis of Rh-based electrocatalytic catalysts by mild methods has been less studied.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a noble metal rhodium hydrogen evolution electrocatalyst and application thereof.

The technical scheme adopted by the invention is as follows: a noble metal rhodium hydrogen evolution electrocatalyst is prepared by the following steps:

(1) loading a carbon carrier on the conductive substrate to obtain a conductive substrate loaded with the carbon carrier;

(2) forming the conductive matrix loaded with the nickel-based phosphate-carbon carrier by an electrodeposition method by using the conductive matrix loaded with the carbon carrier obtained in the step (1) as a working electrode, a graphite rod as a counter electrode and an aqueous solution containing a nickel salt precursor and a phosphorus precursor as a deposition solution;

(3) and (3) forming the conductive matrix loaded with the rhodium oxide-nickel-based phosphate-carbon carrier by an electrodeposition method by using the conductive matrix loaded with the nickel-based phosphate-carbon carrier obtained in the step (2) as a working electrode, a rhodium wire as a counter electrode and sulfuric acid as a deposition solution.

In the step (1), the conductive matrix is one or a combination of glass carbon, platinum, titanium, copper, iron and nickel.

The conductive substrate is glassy carbon, the glassy carbon is firstly wiped clean by cotton wetted by alcohol, polishing is carried out by adopting polishing powder, finally polishing is carried out by adopting polishing cloth, after polishing is finished, the conductive substrate is sequentially placed in ultrapure water and alcohol solution for ultrasonic treatment, and the surface is dried by blowing.

In the step (1), the carbon carrier is dispersed in a solvent to prepare a uniformly dispersed suspension, the suspension is dripped on the conductive matrix, and the conductive matrix loaded with the carbon carrier is obtained after natural drying.

The carbon carrier is carbon black, carbon nano tube or graphene.

The noble metal rhodium hydrogen evolution electrocatalyst and the application thereof in the water electrolysis hydrogen production.

The invention has the following beneficial effects: the rhodium oxide-nickel-based phosphate-carbon carrier is prepared by the two-step electrodeposition mild synthesis method, and has low Rh content. Electrochemical experimental results show that the rhodium oxide-nickel based phosphate-carbon carrier shows excellent HER electrochemical performance, which can be compared with the performance of commercial Pt/C catalyst.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without inventive exercise.

FIG. 1 is a graphical representation of various catalysts. (a, b) NiPi_5c-SEM images of CNTs composites; (c, d) Rh_3h-SEM images of CNTs composites; (e, f) Rh_3h-NiPi_5c-SEM images of CNTs composites;

in FIG. 2, (a) NiPi_5c-CNTs compositesTEM image of the material; (b Rh_3hTEM images and HRTEM lattice fringes within boxes of CNTs composites; (c) NiPi_5c-EDS elemental profile and STEM map and high resolution lattice fringes of CNTs composites; (d) rh_3h-EDS elemental profile and STEM map of CNTs composites;

in FIG. 3, (a, b) Rh_3h-NiPi_5c-TEM images of CNTs composites; (c) rh_3h-NiPi_5cTEM images and HRTEM lattice fringes within boxes of CNTs composites; (d) rh_3h-NiPi_5c-EDS elemental profile and STEM map of CNTs composites;

fig. 4 is a structural characterization of various composite materials: NiPi_5c-CNTs、Rh_3hCNTs and Rh_3h-NiPi_5c-high resolution XPS spectra of CNTs composites, (a) is that of Ni 2P, (b) is that of P2P, (c) is that of Rh 4 f;

in FIG. 5, (a) cathodic polarization curves for different numbers of deposited NiPi-CNTs composites; (a) depositing cathode polarization curves of the Rh-CNTs composite material at different time;

in FIG. 6, (a) different catalysts CNTs, Pt/C, NiPi_5c-CNTs, Rh_3hCNTs and Rh_3h-NiPi_5cCNTs at 0.5M H₂SO₄Sweeping speed of 5 mV s⁻¹(ii) a polarization curve of (a), (b) a tafel slope based on the polarization curve in (a);

in FIG. 7, CV curves for different samples at different sweep rates, and corresponding capacitance values;

FIG. 8 shows NiPi_5c-CNTs、Rh_3hCNTs and Rh_3h-NiPi_5c-nyquist plot of CNTs composites;

FIG. 9 is a graph at 0.5M H₂SO₄In which Rh is measured by chronoamperometry_3h-NiPi_5c-i-t curve of CNTs composite (ŋ = 200 mV vs. RHE);

FIG. 10 shows Rh_3h-NiPi_5cCNTs at 1M KOH and 0.5M H₂SO₄Sweeping speed of 5 mV s⁻¹Polarization curve of (2).

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

1. Pretreatment of glassy carbon electrodes

Firstly, wiping the glassy carbon electrode with cotton wetted by alcohol, and then taking polishing powder (aluminum oxide, Al) with different particle sizes₂O₃) (the particle size is: d = 0.3 μm, d = 0.05 μm) was wetted on a polishing cloth and then polished. And after each polishing, the electrode is washed by ultrapure water, and then polishing is continued. The polishing of the last step is performed on a polishing cloth having only ultrapure water. Each polish was about 1.5 minutes for a total of 3 times. And after polishing, placing the glassy carbon electrode in ultrapure water and ethanol solution successively and ultrasonically treating for 30 s. Finally, the surface of the glassy carbon electrode is dried (high-purity N is used for drying)₂Airflow) and standing for standby.

Preparation of NiPi-CNTs Material

(1) Preparation of CNTs-loaded electrodes

A certain amount (2 mg) of Carbon Nanotubes (CNTs) were weighed into a centrifuge tube, and ultrapure water and an ethanol solution in a volume ratio of 1: 4 (100. mu.l: 400. mu.l) were added to obtain a mixed solution. And placing the centrifuge tube filled with the mixed solution in an ultrasonic cleaning instrument, and performing ultrasonic treatment for 2 hours (the temperature of ultrasonic water is not too high) to obtain uniformly dispersed suspension. On the surface of the pretreated clean glassy carbon electrode, a CNTs suspension (8. mu.l) obtained after ultrasonication was added dropwise using a pipette gun. Naturally dried at room temperature overnight. And obtaining the CNTs loaded glassy carbon electrode.

(2) Preparation of deposition solution

Quantitative nickel chloride (more than or equal to 98 percent), boric acid and sodium hypophosphite reagents are respectively weighed into a beaker, ultrapure water is added, and a volumetric flask is used for preparing deposition solution with the concentration of 0.3M (the concentrations of the nickel chloride, the boric acid and the sodium hypophosphite are all 0.3M).

(3) Synthesis of NiPi-CNTs material by electrodeposition method

By utilizing a three-electrode system, a CNTs loaded glassy carbon electrode is taken as a working electrode, a graphite rod is taken as a counter electrode, and a saturated calomel electrode is taken as a reference electrode, and the working electrode, the graphite rod and the saturated calomel electrode are placed in a device filled with deposition liquid (wherein SC)E was calibrated according to reversible hydrogen electrode calibration). Setting potential window from-1.8 to 0.5V and scan rate of 50 mV s by Cyclic Voltammetry (CV) test^-1. And after circulation, rinsing the deposited electrode with ultrapure water, and naturally drying at room temperature to obtain the NiPi-CNTs loaded glassy carbon electrode. Wherein, the number of cycles of cyclic scanning during deposition is compared, and 2 cycles (2cyc), 5 cycles (5cyc) and 10 cycles (10cyc) are respectively set and recorded as NiPi_2c-CNTs、NiPi_5c-CNTs and NiPi_10c-CNTs。

3. Rh₂O₃Preparation of CNTs Material

(1) Preparation of deposition solution

Measuring a certain amount of concentrated sulfuric acid (H)₂SO₄98%) was placed in a beaker containing a certain amount of ultrapure water, and a sulfuric acid solution having a concentration of 0.5M was prepared using a volumetric flask.

(2) Synthesis of Rh by electrodeposition₂O₃-CNTs materials

By utilizing a three-electrode system, the prepared CNTs electrode is taken as a working electrode, a rhodium wire (Rh wire) is taken as a counter electrode, and a saturated calomel electrode is taken as a reference electrode and is placed in a device filled with deposition liquid. Setting the potential from-1.0V by using a chronoamperometry (i-t) test, continuously dissolving rhodium wires under the hydrogen evolution potential, slowly depositing dissolved particles on a working electrode, and synthesizing Rh₂O₃-a CNTs composite. Screening the deposition time, setting 2h, 3h and 4h respectively, and naming as Rh respectively_2h-CNTs、Rh_3hCNTs and Rh_4h-CNTs。

4. Rh₂O₃Preparation of-NiPi-CNTs material

(1) Preparation of deposition solution

(2) Synthesis of Rh by electrodeposition₂O₃-NiPi-CNTs material

The NiPi-CNTs electrode is used as a working electrode, and a rhodium wire (Rh wire) is used as a counter electrode by utilizing a three-electrode systemAnd Saturated Calomel Electrode (SCE) as a reference electrode in a unit containing 0.5M sulfuric acid deposit. Setting the potential from-1.0V by using a chronoamperometry (i-t), continuously dissolving rhodium filaments under the hydrogen evolution potential, slowly depositing the dissolved particles on a working electrode to synthesize Rh₂O₃-NiPi-CNTs composites. Wherein NiPi is selected_5cPreparation of Rh from-CNTs as a primer₂O₃-NiPi-CNTs material. 3h is the preferred deposition time, so after 3h of deposition Rh is obtained_3h-NiPi_5c-CNTs. Rh used for subsequent characterization₂O₃-NiPi-CNTs composite material is Rh_3h-NiPi_5c-a CNTs composite.

As shown in fig. 1, is an SEM characterization of various composite catalysts. From FIG. 1 (a, b) NiPi_5cAs can be seen in the SEM image of the CNTs composite material, after NiPi is deposited, a large number of uniform spheres grow on the net-shaped surface of the carbon nanotubes, and the spheres are uniformly dispersed and have similar sizes. From the SEM images, the successful deposition of nanoparticles onto CNTs is demonstrated by Cyclic Voltammetry (CV). According to FIG. 1 (c, d) Rh_3hSEM picture of-CNTs composite material, rhodium wire is used as counter electrode, material is deposited on glassy carbon electrode loaded with carbon nano tube, and Rh deposited by i-t method can be seen₂O₃Unlike NiPi, the size is slightly smaller and the sphere is more realistic than NiPi. But the dispersion is also more uniform. It can be seen that the use of rhodium wire as counter electrode successfully deposits material on the surface of CNTs at i-t. From FIG. 1 (e, f) Rh_3h- NiPi_5cAs can be seen in the SEM images of the CNTs composite, the morphology of the particles is preserved and still uniformly distributed, possibly with the second deposited material embedded in the NiPi material or separated from each other for respective shape growth.

As shown in FIG. 2, (a) is NiPi_5cTEM image of a composite of CNTs, it can be seen that there is a more regular spherical morphology, and NiPi of FIG. 2 (c)_5cAs can be seen from the EDS element distribution diagram, STEM diagram and high resolution lattice fringe of the CNTs composite material, NiPi is deposited on the surface of the carbon nanotube and the element distribution is relatively uniform, and from FIG. 2 (c), it can be seen that the material has more obvious lattice fringe corresponding to Ni₂P₂O₇The (12-2) crystal plane of (i.e., NiPi) is a material having a crystal form. FIG. 2(b) Rh_3hTEM images of CNTs composites and HRTEM lattice fringes within the box. The high resolution lattice fringes in the inset correspond to the (111) plane of Rh. From FIG. 2(b) we find Rh deposited₂O₃The particles are not all particles, but rather are nanospheres formed by the agglomeration of a plurality of particles. I-t deposit to synthesize Rh_3hthe-CNTs composite material is Rh simple substance. From FIG. 2 (d) Rh_3hAn EDS element distribution diagram and an STEM diagram of the CNTs composite material have uniform element distribution and can be well matched with highlight particles.

FIG. 3 (a-c) is Rh_3h-NiPi_5cycTEM images of CNTs composites. It can be seen that the granular morphology of NiPi is retained and from fig. 3 (c) it can be seen that the granules have many defects and are not smooth uniform surfaces, which also provides more catalytic sites for catalytic activity to facilitate gas generation and release. In FIG. 2 (c), the insert in FIG. 1 is Ni₂P₂O₇The (12-2) crystal face of (1), the inset (2) is Rh₂O₃And Rh can be seen₂O₃And do not deposit alone, but rather deposit well on the particles of NiPi. As can be seen from the EDS element distribution and STEM chart of FIG. 3 (d), Ni, P, O, Rh were uniformly distributed in the highlighted particle sites, and the second i-t deposition process yielded Rh after oxidation₂O₃It is illustrated that during the longer deposition, there is a simultaneous oxidation process in combination with NiPi. Also by the measurement of the content of ICP element, the content of Rh was determined to be 1.7 wt%, indicating that the composite material synthesized by electrodeposition has a lower Rh content.

Rh was further verified by X-ray photoelectron spectroscopy (XPS)₂O₃The presence of the components and their electronic states in the NiPi-CNTs composite material are shown in FIG. 4.

As seen from FIG. 4 (a), Ni is present in the spectrum of Ni 2p²⁺Peak and Ni³⁺Peak and satellite peak of Rh_3h-NiPi_5c-CNTs composite and NiPi_5cCompared with the CNTs composite material, the peak with low energy level has oneMore significantly toward higher energy levels. FIG. 4 (b), the spectrum of P2P, shows that P exists mainly as P-O bond, via Rh_3h-NiPi_5c-CNTs composite and NiPi_5cComparison of the-CNTs materials shows that the P-O peak shifts to lower energy levels. NiPi-CNTs with Rh₂O₃After binding, the peaks in both the Ni 2P spectrum and the P2P spectrum showed changes, indicating Rh₂O₃The introduction of (b) causes a change in the electronic structure of the material. In fig. 4 (c), the oxidation peak of Rh is significantly increased and has a tendency to move to a higher level, and in the presence of NiPi, the electronic structure of Rh is also changed. Electron transfer due to differences in elemental electronegativity will alter the adsorption energy of hydrogen on the catalyst surface, possibly affecting the HER process.

To study Rh₂O₃The performance of the NiPi-CNTs composite material in electrochemical hydrogen evolution is tested on the electrochemical performance of the catalyst. All electrochemical tests were at 0.5M H₂SO₄Completed in solution environment, the test equipment was Shanghai Chenghua electrochemical workstation (CHI 760). Under room temperature, a three-electrode system was used [ in which a catalyst-modified glassy carbon electrode was used as the working electrode, a graphite electrode was used as the counter electrode, and SCE was used as the counter electrode (SCE was calibrated according to a reversible hydrogen electrode calibration, 0.5M H)₂SO₄In E_RHE=E_SCE+0.267+0.059pH)]. 0.5M H before testing₂SO₄All use high-purity N₂The gas flow was saturated with gas over 30 minutes to eliminate interference from other gases. Linear voltammetry (LSV) test material polarization curve (sweep rate 5 mV s)^-1). Test conditions of CV curve: the test voltage range is 0.1-0.3V vs. RHE, different sweep rates are cycled: 20. 40, 80, 160 and 200 mV s^-1. And alternating current impedance (EIS) curve testing: under the open circuit voltage, the test frequency is 0.01 Hz-100 kHz, and the amplitude is 5 mV. And the stability of the material was assessed by chronoamperometry (i-t) overpotential η = 200 mV vs. RHE.

To explore Rh₂O₃Influence of electronic structure of NiPi-CNTs composite material on performance of NiPi-CNTs composite material is mainly tested by linear voltammetry to obtain a cathode polarization curve (LSV) and a baseAnd (3) displaying electrochemical performances such as Tafel slope (Tafel slope) obtained from an LSV polarization curve, a capacitance diagram obtained by Cyclic Voltammetry (CV), Electrochemical Impedance (EIS), stability and the like. The electrochemical test environment is 0.5M H₂SO₄A three-electrode system (a counter electrode: a graphite rod and a reference electrode: a saturated calomel electrode) is adopted.

A polarization curve with a greater current density at the same potential or a smaller overpotential at the same current density indicates superior HER performance. Therefore, by performing LSV test on NiPi-CNTs composite material deposited for different cycles, as shown in FIG. 5 (a), it can be seen that NiPi obtained when 5 cycles of deposition are performed_5cCNTs composite is the material with the best performance. The increase of the number of deposition turns may cause the NiPi particles to be enlarged, reducing the exposure of active sites, and thus the performance is not excellent. As can be seen from FIG. 5 (b), the i-t method deposits Rh so that the performance of the catalyst is significantly enhanced, and when the deposition time is 3 hours, the current density is 10 mA cm^-2The lowest overpotential is 35 mV. The experimental conditions for Rh deposition were 3 h.

Mixing CNTs, Pt/C, NiPi_5c-CNTs, Rh_3hCNTs and Rh_3h-NiPi_5c-CNTs composite at 0.5M H₂SO₄Sweeping speed of 5 mV s⁻¹LSV test was conducted to obtain the polarization curve of FIG. 6 (a), and it was found that Rh was_3h-NiPi_5cthe-CNTs composite material has excellent hydrogen evolution performance and the current density is 10 mA cm^-2It had a similar overpotential (30 mV) as commercial Pt/C. And exhibits a smaller overpotential at higher current densities than commercial Pt/C. FIG. 6 (b) shows Rh in Tafel slope obtained based on the polarization curve in FIG. 6 (a)_3h-NiPi_5c-CNTs composite with minimum Tafel slope (26 mV dec)^-1) Has excellent hydrogen evolution kinetics. Therefore, Rh₂The ONiPi-CNTs composite material has the hydrogen evolution performance similar to Pt and the Tafel slope superior to Pt. Has excellent hydrogen evolution kinetics, which can be related to the change of the electronic structure of the composite material and the rough and defective particle surface, provides more active sites and is beneficial to the generation and release of hydrogen.

Experiments were generally performed at 0.5M H₂SO₄At different sweeping rates (20 mV s)^-1, 40 mV s^-1, 80 mV s^-1, 160 mV s^-1And 200 mV s^-1) Measurement of electric double layer capacitance (C) of composite Material_dl) To study the electrochemically active area of the nanocomposite. By the CV test method, fig. 7 (a, c, e) was obtained. And (c) linearly fitting according to the relation between different current densities and scanning rates under the potential of 0.2V to obtain the double-layer capacitance of the catalytic material shown in fig. 7 (b, d, f). Can be found out that Rh_3h-NiPi_5cLarger C of-CNTs composite_dlTherefore, the electrochemical active area is the most excellent among the three materials. This is also consistent with TEM results, Rh_3h-NiPi_5cThe particle surface of the-CNTs composite material is rough and has defects, the specific surface area is larger, more active sites can be increased, the transfer and diffusion of substances in the intermediate reaction process are facilitated, and the electrochemical active area is the most excellent.

To further investigate the properties of the composites, Electrochemical Impedance (EIS) tests were performed on different composites, as shown in FIG. 8, Rh_3hCNTs and Rh_3h-NiPi_5cCNTs composite material, compared to NiPi, due to the presence of Rh atoms_5cThe fact that CNTs have smaller radius also implies a larger electron transfer rate indicates that the electrochemical kinetics of the surface of the catalyst has strong charge transfer capability. This corresponds to the electrochemically active area, which is advantageous for the transfer and diffusion of substances, and the rough surface and the presence of defects provide the possibility of promoting the hydrogen evolution reaction.

The stability of the catalyst is also one of the important factors in evaluating the hydrogen evolution activity of the catalyst. There are generally two methods to assess the stability of a material: firstly, a timing current method (i-t) is utilized to give a certain potential and observe the change of current density along with time; and secondly, after the LSV is circulated for a certain time or a certain number of times, the LSV before and after the circulation is tested, and the performance attenuation condition is compared. The first method was used to evaluate the material stability in this experiment. As can be seen from FIG. 9, in an acidic medium, the overpotential at higher levels is 200 mV (vs. RHE) test for 45 h, Rh_3h-NiPi_5cCNTs composites exhibit a relatively smooth current density over time, with no significant change. Description of Rh_3h-NiPi_5cThe CNTs composite material has excellent acid corrosion resistance and stable electrochemical activity.

The catalyst has excellent hydrogen evolution performance in an acidic medium, so the performance in an alkaline medium is preliminarily tested. As can be seen from FIG. 10, it also shows excellent catalytic performance in a 1M KOH solution, at a current density of 10 mA cm^-2The overpotential was 42 mV. The material has excellent hydrogen evolution performance in acid-base environment and has wide application prospect.

In summary, this example prepares a low noble metal/transition metal phosphorus oxide composite (Rh) by a two-step electrodeposition, a mild synthesis method₂ONiPi-CNTs), with a lower Rh content (1.7 wt%). The appearance of the sample is characterized by SEM, TEM and EDS, and NiPi and Rh are proved₂O₃Upon successful loading, the granular structure may expose a larger contact area. The XPS test is used to research the structure of the composite material, NiPi and Rh₂O₃The combination of (a) causes a change in the electronic structure of the composite material. Electrochemical experiment results show that Rh is₂ONiPi-CNTs exhibit excellent electrochemical performance of HER: at a current density of 10 mA cm^-2The catalyst reaches lower overpotential (which can be compared with the performance of a commercial Pt/C catalyst) of 30 mV (in an acidic medium) and 43 mV (in a basic medium), and the Tafel slope is 26 mV dec^-1And good stability in acidic media.

Synergistic effect of carbon nanotubes, NiPi nanoparticles and low noble metal rhodium oxide to increase Rh₂The electrocatalytic activity of the ONiPi-CNTs nano composite material is a strategy for effectively designing a catalytic material with low content of noble metal and non-noble metal and low cost. Preliminarily confirmed the deposition of Rh₂O₃More active sites are added while forming defects with NiPi, and a new idea is provided for synthesizing a catalyst with high efficiency, high stability and no platinum.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.

Claims

1. A noble metal rhodium hydrogen evolution electrocatalyst is characterized in that the preparation process comprises the following steps:

2. The noble metal rhodium hydrogen evolution electrocatalyst according to claim 1, characterized in that: in the step (1), the conductive matrix is one or a combination of glass carbon, platinum, titanium, copper, iron and nickel.

3. The noble metal rhodium hydrogen evolution electrocatalyst according to claim 2, characterized in that: the conductive substrate is glassy carbon, the glassy carbon is firstly wiped clean by cotton wetted by alcohol, polishing is carried out by adopting polishing powder, finally polishing is carried out by adopting polishing cloth, after polishing is finished, the conductive substrate is sequentially placed in ultrapure water and alcohol solution for ultrasonic treatment, and the surface is dried by blowing.

4. The noble metal rhodium hydrogen evolution electrocatalyst according to claim 1, characterized in that: in the step (1), the carbon carrier is dispersed in a solvent to prepare a uniformly dispersed suspension, the suspension is dripped on the conductive matrix, and the conductive matrix loaded with the carbon carrier is obtained after natural drying.

5. The noble metal rhodium hydrogen evolution electrocatalyst according to claim 1, characterized in that: the carbon carrier is carbon black, carbon nano tube or graphene.

6. Use of a noble metal rhodium hydrogen evolution electrocatalyst according to any one of claims 1-5 in the electrolysis of water to produce hydrogen.