Preparation Of The Transition Metal Phosphides/Carbonized Wood Composites And The Investigation Of Their Electrocatalytic Performance

Using catalysts with excellent catalytic activity can reduce the overpotential in the reaction process of water electrolysis and improve the efficiency of energy conversion,in the technology of hydrogen production from water electrolysis.Therefore,it is of great significance to explore and develop efficient and cheap catalysts.As a natural and renewable biomass material,wood is cheap and easy to obtain and easy to process.However,the fact that wood does not conduct electricity limits its range of applications.Carbonized wood obtained by high-temperature carbonization has good electrical conductivity and keeps the structural advantage of wood,which is expected to be applied in the field of hydrogen production by electrolysis of water.Transition metal phosphating is considered one of the most promising non-noble catalysts.However,the poor conductivity and insufficient exposure of catalytic active sites,its catalytic activity is low in practical applications.Therefore,this thesis proposes the strategy of developing carbon-based electrodes and building heterostructure to improve the catalytic activity of nickel phosphide,reduce the overpotential of hydrogen evolution reaction and oxygen evolution reaction of electrolytic water,and improve the energy conversion efficiency.At the same time,explore ways for wood development and efficient utilization.The conclusions are as follows:（1）Basswood was used as raw material,pre-carbonized at 260℃ in air,and carbonized at 700℃,800℃,900℃ and 1000℃ in argon atmosphere to obtain carbonized wood.The carbonized wood at1000℃ had the best conductivity(conductivity of 21 S cm^-1)and retained the porous structure and hydroxyl functional groups of the original basswood.Carbonized wood（CW）has advantages in structure,chemical composition and electrical conductivity,which is a potential substrate material.（2）The nickel/nickel phosphide/carbonized wood hydrogen evolution electrode(Ni/Ni₁₂P₅/CW)was prepared by solvothermal and electroplating methods with carbonized wood as the substrate.In an alkaline environment,Ni/Ni₁₂P₅/CW can reach a current density of 10 m A cm^-2 with only 86 m V and can work continuously at different current densities of 20,40,60,80,and 100 m A cm^-2 for 60 hours.Indicates the good hydrogen evolution activity and stability of Ni/Ni₁₂P₅/CW.（3）The nickel-phosphorus/nickel hydroxide/carbonized wood oxygen evolution electrode（NiP/Ni（OH）₂/CW）was prepared by hydrothermal and electroplating methods with carbonized wood as the substrate.The NiP/Ni（OH）₂/CW exhibited excellent oxygen evolution reaction catalytic activity,which required overpotentials of 325 m V to drive 100 m A cm^-2 in the alkaline environment,and can work stably for more than 15 hours without obvious attenuation at the current density of 15 m A cm^-2.The Ni/Ni₁₂P₅/CW and NiP/Ni（OH）₂/CW were assembled,and the water splitting test was performed in 1.0M KOH.It takes 1.73 V to reach a current density of 50 m A cm^-2and works for 20 hours at a current density of 10 m A cm^-2 without obvious attenuation.