| Hydrogen energy is regarded as one of the most promising renewable energy sources due to its wide source,high calorific value of combustion,high efficiency and zero pollution.Electrocatalytic hydrolysis technology can utilize the earth’s abundant water resources and produce hydrogen with high purity,which provides an effective way for the clean production of hydrogen energy.However,since the hydrolysis process involves multiple electron transfer steps,especially the anodic oxygen precipitation reaction(OER),a high overpotential is required to achieve a significant catalytic current density,resulting in a relatively low energy conversion efficiency.Conventional OER electrocatalysts are mainly based on noble metal-based materials,but their rarity and high cost limit their large-scale industrial application.Therefore,the development of high-performance non-precious metal OER electrocatalysts is of great significance to promote the sustainable development of hydrogen energy.Transition metal Fe-based materials with tunable electronic geometry and rich multiple valence distribution have become a hot research topic in electrocatalysis.However,most Fe-based oxide materials still face the disadvantages of insufficient active sites,poor electrical conductivity and easy solubility in alkaline solutions,which make their electrocatalytic activities not optimal.Therefore,in this project,FeV and FeCo bimetallic layered hydroxides(LDHs)were used to synthesize three-dimensional self-supporting structure catalysts by a simple hydrothermal method to achieve the modulation of electronic structure and active sites by using the bimetallic electronic synergy and highly ordered three-dimensional structure,which effectively reduces the effect of Fe based materials intrinsic activity on the electrocatalytic OER performance.Further,the activity and stability of the electrocatalysts were improved by suppressing the dissolution of metal active sites through metal atom deposition strategy.The final focus is on the catalytic reaction mechanism of Fe-based electrocatalysts,which provides new ideas for an in-depth understanding of different surface interface modulation strategies for optimizing the electrocatalytic activity of Fe-based self-supported structural materials.Specific research contents are as follows:(1)The electrocatalytic OER activity and stability of the three-dimensional self-supported FeV-LDHs catalyst were effectively improved by the VOOH deposition strategy.Firstly,FeV-LDHs catalyst with three-dimensional self-supporting structure was prepared.It was found that it had excellent OER catalytic activity,but its stability was reduced due to a large amount of V site dissolution in the reaction process.Further,FeOOH and VOOH were deposited on the surface to form FeOOH/FeV-LDHs and VOOH/FeV-LDHs composite catalysts,which optimized the number of active sites and electronic structure.It was found that the VOOH/FeV-LDHs composite catalyst showed the best OER catalytic activity and stability.At the current density of 50 mA/cm2,the potential decreased from 1.49 V vs.RHE to 1.45 V vs.RHE,and the stability remained above 48 h.Faraday efficiency is close to 98%.(2)The electrocatalytic OER activity and stability of FeCo-LDHs were improved by N2 plasma etching and FeOOH modification.The FeOOH/FeCo-LDHs composite electrocatalyst was prepared by plasma etching to form a large number of active sites and unsaturated vacancy structures on the surface.The electrochemical test showed that the potential decreased from 1.49 V vs.RHE to 1.43 V vs.RHE at the current density of 10 mA/cm2,and remained stable at 48 h stability test.The mechanism study found that a large number of oxygen vacancies and unsaturated metal sites were generated on the catalyst surface by N2 plasma treatment,which formed a close interfacial interaction with FeOOH.This structure increases the stability of the active site and imroves the electron transfer rate,so the FeOOH/FeCo-LDHs composite catalyst exhibits high catalytic activity and stability. |
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