Preparation And Electrocatalytic Performance Of Transition Metal Phosphides Derived From Metal-Organic Framework Materials

The global economy continues to develop rapidly and with the growth of the world’s population,the annual global energy consumption continues to grow rapidly.In particular,the rapid consumption of disposable fuels such as coal,oil,and natural gas has brought a round of pollution problems that have become increasingly serious.As the most promising clean energy in the future,zero-carbon hydrogen（H₂）can deal with a series of environmental and energy problems caused by the burning of fossil fuels.The use of electrochemical decomposition of water to produce hydrogen is regarded as the most promising strategy for current production of hydrogen.Therefore,a lot of work has been done to develop low-cost,high-performance and non-Pt,Ru and Ir noble metal-based electrocatalysts for water splitting.At the same time,in order to reduce the cost of preparing electrocatalysts,it is urgent to explore dual-functional electrocatalysts that can simultaneously perform oxygen evolution reaction and hydrogen evolution reaction in the same electrolyte.Transition metal phosphides（TMPs）are considered to be a very promising class of dual-function electrocatalysts for HER and OER.However,single metal-based phosphides usually exhibit excellent HER or OER performance,resulting in unsatisfactory total water splitting activity.For this reason,adopting appropriate strategies to design and construct heterostructure electrodes is essential for preparing bifunctional transition metal phosphide electrode materials with enhanced interfacial effects to achieve effective water splitting.Based on the above factors,this thesis conducted the following research:1.The zeolite imidazole salt skeleton-67（Co/Ni-LDH@ZIF-67）coated with Co/Ni double-layer hydroxide was pyrolyzed at high temperature,and then CoP and Ni₂P nanoparticles embedded in hollow N doped with porous carbon polyhedrons electrocatalyst were prepared by oxidation and low-temperature phosphating strategies.The introduction of LDH can not only promote the formation of a hollow porous structure to supply more active sites,but also generate the CoP/Ni₂P nanoheterostructure to afford extra active sites and modulate the electronic structure of the catalyst.As a result,CoP/Ni₂P@HPNCP exhibits excellent p H universal hydrogen evolution reaction activity and alkaline oxygen evolution reaction activity.Furthermore,the electrolytic cell assembled from bifunctional CoP/Ni₂P@HPNCP requires a cell voltage of 1.59V in 1.0 M KOH at 10 m A cm^-2,revealing its potential as a high performance bifunctional electrocatalyst.2.The Ni-doped zeolite imidazole salt skeleton-67（ZIF-67）was pyrolyzed in a mixed atmosphere containing hydrogen directly,and after low-temperature phosphating technology,Ni-doped hollow CoP nanoparticles were prepared to embed N-doped porous carbon nanotube polyhedron（Ni-CoP@NPCNP）catalyst material.The doping of metallic Ni forms highly active hollow Ni-doped CoP nanoparticles,which have a strong synergy with the N-doped carbon nanotube hollow polyhedrons,and the optimized electronic structure and adsorption of catalyst can effectively promote the electrocatalytic performance.