Synthesis And Catalytic Properties Of Noble-Metal-Free Electrocatalysts For Water Splitting

Hydrogen,as a cleaner,renewable alternative to fossil fuels,has attracted much attention because of the global energy demand and environmental crisis.There are many ways to produce hydrogen,electrolysis of water is a very important method of hydrogen production.In the process of electrolysis of water,it consists of two half reactions: oxygen evolution reaction（OER）occurs in the anode and the hydrogen evolution reaction（HER）occurs in the cathode.It is of great practical significance to find an electrolytic water catalyst with high efficiency,stability and cheapness.This paper starts from two directions and designs catalysts for water splitting.On the one hand,with respect to the oxygen evolution reaction（OER）,we designed the WO₃@α-Fe₂O₃ heterojunction array for use in photoelectrochemical hydrolysis in a neutral environment.By measuring α-Fe₂O₃ on the WO₃ nanosheet,the current density is almost six times that of the original,the onset potential is 260 mV,and the IPCE reaches 73.7% at 390 nm.In addition,the stability of the heterojunction anode in the neutral environment is also very good.The photocurrent still retained almost the same photocurrent density as the initial value after 10 h of reaction.The structure of this unique nanostructured heterojunction expand the spectral range of light absorption and promote photogenerated electron-hole separation/transfer,thereby improving the photoelectrochemical water splitting performance of the catalyst.On the other hand,with respect to the hydrogen evolution reaction（HER）,we developed the hydrogen evolution catalyst B-Mo₂ C by calcining the butterfly wings of the molybdenum-doped biomaterials.After the electrochemical performance test,when the current density of 10 m A cm-2,its voltage is 0.192 V,the onset potential is 0.09 V.In addition,the stability of the catalyst in the acidic environment is also very good,The photocurrent still retained almost the same photocurrent density as the initial value after 11 h of reaction.This method not only synthesizes the hydrogen evolution catalyst Mo₂ C,but also uses the biological material of butterfly wings as the carbon source to increase the specific surface area,thus improving the catalytic performance of B-Mo₂ C hydrogen evolution.