Synthesis And Electrocatalytic Water Decomposition Of Transition Metal Phosphides Derived From Carboxylic Metal Organic Frameworks

Electrocatalytic decomposition of water is considered to be a practical strategy to promote the conversion of sustainable energy such as solar energy and wind energy from electricity to clean hydrogen fuel.In order to realize large-scale hydrogen production,it is very important to develop low-cost,efficient and stable electrocatalysts.Metal organic framework（MOF）and its derivatives have been proved to be efficient water decomposition catalysts because of their large surface area and rich active centers.The application of MOF derived nanostructured materials in electrocatalysis was studied in this paper.The synthesis method of MOF nano materials was explored,and different types of electrocatalysts were prepared by derivatization,which improved their electrocatalytic activity and stability.This study provides some new ideas for electrocatalytic water decomposition.（1）The Co_xFe_y-MOF composite structure was synthesized by adding different proportions of metal Co and Fe solutions into 4,6-pyrimidine dicarboxylic acid solution and stirring at room temperature.Then the synthesized bimetallic MOF material was pyrolyzed and phosphated to prepare the composite structure Co_xFe_yP@CN layered composites.The synthesized material was loaded on 1cm²graphite sheet with prepared conductive adhesive to make working electrode.The properties of oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）were tested in an electrolytic cell with 1M KOH solution as electrolyte.Found in OER performance test Co₃Fe₁P@CN at a current density of 10 m A·cm^-2,the voltage is 294 m V.In HER performance test Co₃Fe₁P@CN at a current density of 10 m A·cm^-2,the voltage is 161m V.（2）Based on the exploration of the first chapter,Ni/CO bimetals were prepared Co_xNi_yP@NC bifunctional electrocatalyst.The performance of electrocatalytic OER and HER has been further improved.The research shows that for the optimized Co_0.82Ni_{0 18}P@NC,the over potentials of electrocatalyst,HER and OER were as low as 140 m V and 280 m V at 10 m A·cm^-2,respectively.In addition,fully decomposed water（OWS）can be started at a voltage of 1.67 V.This MOFs limits the pyrolytic phosphating strategy derived from Co_0.82Ni_{0 18}P@NC electrocatalyst has the advantages of high activity,low cost and good durability.It has broad application prospects in the field of water decomposition.（3）The ligand dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid solution and the transition metal salt solution were mixed.Using water and N’N-dimethylformamide as solvents,the nanostructured Co_xFe_y MOF material was synthesized by hydrothermal method.The transition metal phosphide（TMP）prepared after phosphating was used as electrocatalyst.The electrocatalysis performance was good.The oer overpotential of the optimized sample Co₃Fe₁-P was as low as 223mv at 10 mA·cm^-2.