Study On Modification Of Transition Metal Dihydroxy/Ni Foam Catalysts And The Electrocatalytic Hydrogen Evolution Performance

At present,the major hydrogen production techniques mostly are fossil fuel hydrogen production,biomass hydrogen production,water-splitting hydrogen production and so on,among which the water-splitting hydrogen production solely undertake less than 4%of the whole production tasks.During the process of efficient hydrogen evolution reaction,catalysts are utilized to achieve the purpose of enhancing reaction kinetics,thereby triggering the reduction of H⁺at low potential.The conventional catalysts mainly are precious metals with low abundance and expensive price such as Pt,Ru and Ir.Compared with precious metals,transitional metals possess ideal application prospect in HER due to the characteristics of underfilled d orbital,the convenience to combine with other substances and the relatively low price.However,these factors,including the unideal catalytic performance and poor stability,restrict the large-scale application in the pratical production process.Therefore,we make three kinds of effective improvement strategies towards the above-mentioned problems,which are listed as below.（1）Three dimensional network structure（Ru O_X（0.24%）-Ni（OH）₂/NF）with Ru quantum dots intercalating inside Ni（OH）₂ layers is assembled by one hydrothermal step,based on Ni foam.Because of the strong binding effect between Ni（OH）₂layers and Ru quantum dots,Ni（OH）₂layers and Ru quantum dots can work synergistically,thereby effectively reducing the potential of hydrogen evolution reaction.The catalysts（Ru O_X（0.24%）-Ni（OH）₂/NF）shows excellent catalytic performance,which exhibit the remarkably low HER overpotential of 27.1 m V to drive 10 m A·cm^-2.The overpotential is just 105.1 m V even under 300 m A·cm^-2,demonstrating the large application potential.（2）The carbon quantum dots are prepared by the decomposition of glucose under hydrothermal condition,then reacting with Ni（NO₃）₂,Co（NO₃）₂ and Zn（NO₃）₂.Carbon quantum dots can be in-situ intercalated between layers of dihydroxy catalysts by utilizing the electrostatic effect between carbon dots and metal ions.Catalysts prepared by hydrothermal method are placed in tube furnace to calcine in 600℃,with the result of getting NCZ-CDs-600.Catalysts with three-dimension and porous channel structure are prepared by utilizing the property of easy escape of Zn at high temperature.The low Tafel slope(108.62m V·dec^-1)and hydrogen evolution overpotential（171.23 m V）and the corresponding oxygen evolution potential is merely 358.00 m V at 50 m A·cm^-2,which all demonstrate the great prospect of carbon dots in the preparation of HER and OER catalysts.（3）During the process of the decomposition of glucose under hydrothermal condition,the preparation of carbon nitride quantum dots is achieved by adding the ethylenediamine solution.Carbon nitride quantum dots are complexed with metal ions（nickel,cobalt and ruthenium）through 5-amino-1,10-phenanthroline to synthesize carbon quantum dot-metal ion complexes.After the process of complexing,carbon nitride dots are put into the mixed solution contained Ni²⁺,Co²⁺and Zn²⁺to prepare NCZ-NCR/CDs（N）through hydrothermal reaction.The overpential of NCZ-NCR/CDs（N）is 53.02 m V at 10 m A·cm^-2,meanwhile,when the current density reaches 100 m A·cm^-2,the corresponding potential is only 163.75m V.The relatively lower charge transfer resistence（3.43（?））and Tafel slope(73.81 m V·dec^-1)also prove the exceptional reaction kinetics of NCZ-NC/CDs（N）.This experiment method provides a new solution towards the synthesis of mutil-metal based catalysts.