Controllable Construction And Catalytic Properties Of Self-supporting Structures Of Transition Metal Nickel-based Compounds

Electrochemical splitting water breaks the balance of the system under the action of the current,and makes the water of the system decompose continuously.This review focuses on the economical,energy saving and highly active nickel base electrocatalysts for reducing the overpotential of reactions by exposing specific energetic surfaces,multiple active sites,and large specific surface areas;increasing the current density and increasing the utilization efficiency of electric energy by using metal as the carrier to increase the transmission capacity of electrons and improve the density of carriers.In the first part of this paper,the controllable structures of transition metal sulfides are discussed.The synthesis of nickel sulfide was carried out by a simple one-step process of sulfuration of the precursor.The performance of electrocatalytic hydrogen production is-115 mV vs.RHE when the current density at 10 mA cm^-2.In the second part of the paper,we mainly introduce the precursor of the synthetic flower like structure,and then selenation the precursor to obtain the two nickel selenide nanostructure.Comparing the electrocatalytic activity of these two catalysts,it is found that the reaction activity of nickel selenide is superior,which indicates that nickel based material has the same surface state,but nickel selenide has stronger metal and faster electron transport.At 10 mA cm^-2,the over potential of two nickel selenide synthesized at 450 ^oC is-105.3 mV.In the third part using the traditional hydrothermal method,the synthesis of flower like microspheres nickel hydroxide nano self-assembled film on titanium substrate,though chemical vapor deposition method to generate four five nickel phosphide phosphate.This is a supporting electrode exposed?001?high specific activity,effectively reduce the overpotential and improve the catalytic current.We have proved the existence of?001?high-energy surface by means of DFT theoretical calculation.When the current density is 10 mA cm^-2 corresponding overpotential of Ni₅P₄electrocatalyst is-35.4 mV.Then,the control of the surfactant through the control of a nanowire and two-dimensional nanoplates self-assembly,exposed more active sites,so that electrolyzed water hydrogen evolution overpotential is lower,and further improve the catalytic activity.It is found that when the Ni5P4 current density of multistage structure at 10 mA cm^-2,the overpotential is-29.8 mV.