Synthesis Of Cobalt Phosphide-based Electrocatalyst And Its Application In Electrocatalytic Oxidation Of 5-hydroxymethylfurfural

With the increasing scarcity of fossil resources and the development of renewable energy,transforming biomass resources into high value-added products to replace fossil fuels is one of the important ways to achieve sustainable energy development.Among them,5hydroxymethylfurfural(HMF),as a bridge between biomass energy resources and chemical industry,has attracted extensive attention in the field of electrocatalysis.In this paper,Ce-doped CoP nanosheets and Cu2P7-CoP nanosheets with porous structures are synthesized by using choline chloride/oxalate deep eutectic solvents(DES)combined with atomic doping strategy and heterostructure construction strategy respectively,and they were applied to electrocatalytic oxidation of HMF.The experimental results show that these two new catalysts have excellent electrocatalytic HMF oxidation performance and have good application prospects.In addition,the mechanism of enhancing the electrocatalytic performance of the synthesized nanosheets is revealed by open-circuit potential method and density functional theory calculation,which provide a theoretical basis for future research.Two specific research tasks are as follows:(1)For the first time,we synthesize Ce-doped CoP nanosheets with porous structure by using choline chloride/oxalic acid DES combined with atomic doping strategy,in which atomic doping,vacancy defects and porous two-dimensional structure are simultaneously integrated in cobalt phosphide-based materials.CoCl2 and Ce(NO3)3 powders are dissolved in choline chloride/oxalic acid DES,and then the Ce-doped CoP nanosheets with phosphorus vacancy and porous structure are prepared by microwave and phosphating.The Ce-doped CoP nanosheet catalyst with the best performance is obtained by adjusting the proportion of Ce doping.Thanks to the rich phosphorus vacancies,unique nanosheet structure and optimized electronic structure,the prepared 5.2%Ce-CoP nanosheet show excellent electrocatalytic HMF oxidation performance in 1.0 M KOH electrolyte containing 10 mM HMF at 1.44 V(vs.RHE)voltage.The HMF conversion rate of 100%,FDCA yield of 98%and Faraday efficiency of 96.4%are obtained,which are better than most Co-based electrocatalysts reported before,and have a good application prospect in the field of electrocatalytic HMF oxidation.We also reveal the mechanism of enhancing the electrocatalytic performance of Ce-CoP nanosheets by opencircuit potential method and density functional theory calculation.(2)Because the activity of water oxidation(the competitive reaction of HMF oxidation)is usually lower than that of Ni/Co-based materials,Cu-based materials have attracted more and more attention in the field of HMF electrocatalytic oxidation.Therefore,we first propose and use choline chloride/oxalic acid DES to combine Co-based and Cu-based materials effectively,and synthesize Cu2P7-CoPheterostructure nanosheets,which are used for electrocatalytic HMF oxidation.In 1.0 M KOH electrolyte containing 10 mM HMF,the synthesized Cu2P7-CoP(1:5)heterostructure nanosheets show excellent electrocatalytic HMF oxidation performance at lower potential(1.43 V vs.RHE)(HMF conversion rate:100%;FDCA yield:98.8%;Faraday efficiency:98%),which exceeds most electrocatalysts reported.