Preparation And Properties Of Heteropoly Acid Doped Polypyrrole Derivatives Hydrolyzed Catalysts

Hydrogen production by electrolysis is attracting attention because it is clean and sustainable.At present,the best electrocatalysts for hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）are Pt and Ir/Ru based compounds,respectively.However,its scarcity and high cost greatly hinder its wide applicationin in the field of hydrolysis hydrogen production.Therefore,it is a great challenge to replace these precious metals with efficient and novel monofunctional water splitting electrocatalysts based on abundant and inexpensive elements on earth.Although single-function catalysts for hydrogen or oxygen evolution require different equipment and preparation process,which is cumbersome and leads to high cost.In addition,the scarcity and high cost of elements greatly hinder the application of acid electrolysis of water,so alkaline water cracking has become a strong candidate for industrial hydrogen production.Therefore,it is of great significance to study the integral water cracking of non-expensive bifunctional electrocatalysts in an alkaline medium.In this paper,heteropoly acid doped polypyrrole derivatives were prepared by electrodeposition and carbonization.As a catalyst for water electrolysis,it shows not only excellent performance of hydrogen and oxygen evolution but also has long-term stability.The specific research contents are as follows:（1）Self-supported phosphotungstic acid doped polypyrrole precursor PPY-PW₁₂ was prepared by electrodeposition,and the precursor was calcined.The prepared W/Ni₃（PO₄）₂@NC/NF electrocatalyst has good HER and OER properties.When the current density is 10 m A cm^-2 in 1.0M KOH,the corresponding hydrogen evolution overpotential only needs48 m V,and oxygen evolution overpotential only needs 236 m V.In addition,when W/Ni₃（PO₄）₂@NC/NF is used as a bifunctional catalyst for global water cracking,it requires only 1.53 V to provide a current density of 10 m A cm^-2.This work provides a feasible strategy for using phosphotungstic acid doped polypyrrole as a practical self-supported catalyst precursor for hydrolysis.（2）Silicotungstic acid doped polypyrrole precursor was prepared by electrodeposition and then calcined to prepare the catalyst.Four kinds of ultra-high loading catalysts were prepared by adjusting the content of silotungstic acid in the electrolyte.The load of the catalyst increases with the increase of the content of silicotungstic acid in the electrolyte.As the number of nanorods on the catalyst surface increases,the more active sites are exposed,and the catalytic performance is improved.However,the excessive number of nanowires leads to the aggregation of nanorods,which is not conducive to the catalytic reaction.Therefore,the catalytic performance of the catalyst increases first and then decreases with the increase of catalyst loading.The results show that when the amount of silicotungstic acid in the electrolyte is 4317 mg,the catalytic effect of water electrolysis is the best.When the current density is 20 m A cm^-2,HER overpotential is 69.46 m V and OER overpotential is 246 m V.In addition,when 4317 was applied to a total water cracking dual-function catalyst,it required only 1.6 V to reach a current density of 10 m A cm^-2,and the catalyst voltage remained unchanged at a current density of 50m A cm^-2 for 100 h without significant change.This work provides a simple and feasible method for preparing ultra-high loading on nickel foam,and provides a new idea for optimizing catalytic performance by adjusting the loading.