Synthesis Of Ni,Co-based Metal-organic Frameworks And The Study Of Their Electrocatalytic Performance

The energy crisis and environmental pollution caused by the consumption of fossil energy have become two major problems.In order to achieve low carbon emissions and improve energy security,it is imperative to develop and utilize clean and renewable energy.As a "carbon reduction expert",hydrogen energy is regarded as the clean energy with the most potential for development in the 21st century due to its high calorific value and energy density,abundant sources and non-polluting product.So far,industrial hydrogen production is mainly based on steam methane recombination and coal gasification,which consumes a lot of resources,produces low purity hydrogen,a lot of pollutants and high carbon emissions.Water splitting is one of the environmentally friendly hydrogen production paths,and the efficient catalysts are the key to improving the efficiency of hydrogen production.Therefore,in this paper,metal-organic framework(MOF)was used as the research object,two kinds of high-efficiency electrocatalysts were prepared by surface modification to construct the interface and regulating the internal coordination form,which successfully reduced the energy consumption of hydrogen production from water splitting.The reaction mechanism and electrochemical performance of the two catalysts in the process of electrocatalysis were studied.The specific research results are as follows:(1)The NiCo-BDC was optimized based on the surface modification to construct the interface,and the NiCo-BDC/Ni-S nanocomposite with both oxygen evolution reaction(OER)and urea oxidation reaction(UOR)capabilities was synthesized.The modification of NiCo-BDC with Ni-S film layer promotes the adjustment of its intrinsic electronic structure,improves the conductivity and the intrinsic activity of active sites,and accelerates the charge transfer rate.In addition,the synergistic effect of the two substances at the interface improves the absorption and desorption ability of the reaction intermediates,and accelerates the reaction kinetics.When the NiCo-BDC/Ni-S and Pt/C are assembled into overall water splitting system,the driving potential of urea full hydrolysis(1.46 V vs.RHE)is lower than that of overall water splitting(1.53 V),which proves that using UOR,Urea instead of OER can not only effectively reduce the driving voltage for hydrogen production,but also realize the decomposition of urea in wastewater.(2)The NiCo-BDC was optimized by regulating the internal coordination forms,and the Fc-NiCo-BDC triangular nanosheet material with efficient oxygen evolution was successfully synthesized.When the Fc-NiCo-BDC is combined with Pt/C to drive overall water splitting,only a driving potential of 1.49 V(vs.RHE)was applied.By introducing monocoordinated ferrocenecarboxylic acid(Fc),NiCo-BDC exposed more unsaturated sites and reconstructed electrons.The adsorption and desorption ability of NiCo-BDC to reaction intermediates was optimized,making it more consistent with Sabatier rule.In addition,the introduction of Fc can reduce the band gap of NiCo-BDC,significantly improve its conductivity,accelerate the charge transfer,and effectively improve the catalytic performance.