| With the comsuption of traditional fossil fuels and the accumulation of carbon emissions,clean and renewable hydrogen is the next generation of major energy source in the future.Economic and large-scale hydrogen production is a prerequisite for achieving the“hydrogen economy”.Aiming at obtaining inexpensive and efficient electrocatalysts,most of the used-catalysts are mostly about transition metal based catalysts which can reduce energy consumption and improve electrolysis efficiency.At present,there are several strategies to effectively reduce the energy barrier required for water electrolysis.On one hand,the electrocatalytic performance is closely related to the intrinsic material property.On the other hand,the original oxygen evolution reaction can be replaced by the half-reaction with lower required energy.Therefore,it is particularly important to find and develop effective ways to reduce energy consumption and improve efficiency.The research is around cobalt-based catalysts.And the application of transition metal compound catalysts in water electrolysis systems is also explored.The general methods of reducing the required of water electrolysis systems are used through materials and reactions.1.Electrodeposition,especially cathodic reduction of metal oxyacid anions,is a widely used strategy for constructing self-supporting catalysts.It has the advantages of highly efficient active site utilization and simple manufacturing processes.We have developed a one-step electrodeposition method to synthesize CoV?hydr?oxides as an excellent self-supporting OER catalyst with high activity,stability and low cost.With strong 3D interconnected nanosheet structure and electronic synergy effect between Co atom and V atom,its OER activity can reach 100 mA cm-2 with only 345 mV overpotential.2.Vanadium is a preferred dopant as a typical 3d transition metal with enough vacancy d orbitals and multiple valence states.The one-step electrodeposition method of introducing vanadium is a generally applicable strategy for effectively improving the electrocatalytic performance of transition metal?hydr?oxides.Doping 3d transition metal vanadium can effectively adjust the center of the d-band of the host material,provide more active sites or change the electronic structure,thereby essentially promoting the electrocatalytic activity.Therefore,we prepared a series of transition matal based catalyst and explored the catalytic activity of the catalyst with or without vanadium doping.3.We synthesized CoCH/Cu Foam using a one-step hydrothermal method.This cobalt carbonate hydroxide catalyst reduces the potential for hybrid water electrolysis to1.271 V@10 mA cm-2,with nearly 100%HMF conversion,close to 100%FDCA selectivity,and the 99%Faraday efficiency.The catalyst refreshes the lowest performance in HMF electrooxidation and hybrid water electrolysis.In addition to the highest electrochemical performance and superior product selectivity,we also investigated the factors affecting the concentration of the reactants,the concentration of the alkaline electrolyte,the forced convection of the agitation and the type of exchange membrane in the HMF oxidation to determine the experimental standard conditions.Based on all experimental data,we first explained the following issues:i)the relationship between OER and HMF electrooxidation;ii)the possible causes and improvement measures of low current density in HMF electrooxidation. |
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