The Preparation Of Cobalt And Nickel-based Nanomaterials And Their Application In Electrocatalytic Water Splitting

At present,due to the rapid depletion of fossil fuel reserves coupled with the increasing ecological environmental problems,people are gradually aware of the importance of sustainable development.The development of clean renewable energy sources such as solar energy,wind power,tidal energy,hydrogen energy,etc.,is an effective solution to replace the traditional fossil energy.Hydrogen has long been considered as an ideal alternative energy source due to its high calorific value,cleanness and feasibility in transportation and storage.Water electrolysis is considered as an effective way for large-scale production of high purity hydrogen gas.The traditional reaction of water electrolysis cell consists of two and a half reactions:a cathode for hydrogen evolution reaction(HER)and an anode for oxygen evolution reaction(OER).Both reactions need a higher overpotential to reach its expected reaction efficiency,which caused that the actual applied voltage required of the whole water electrolysis is much larger than its theoretical value(1.23 V).Therefore,the development of efficient OER and HER catalysts to reduce the overpotential and improve the energy conversion efficiency of the whole water electrolysis reaction becomes the research focus in the field of clean energy.At present,Pt-group metals are the most active HER catalysts and IrO2 and RuO2 are the benchmark OER catalysts,but the high cost and unsustainable supply of such precious metal catalysts hinder their practical wide application in industrial production.As a result,the researchers’eyes turned to the first transition metal elements,which are relatively cheap and earth-abundant.Herein,this dissertation is aimed at constructing high activity and high stability OER,HER and overall water-splitting catalysts by different preparation methods.The main research contents include the following aspects:1.We reported a facile and efficient co-precipitation method assisted by polyvinylpyrrolidone(PVP K30)to fabricate CO3(OAc)5OH particles.The as-prepared CO3(OAc)5OH precursors was then calcinated at different tempretures to fabricate the uniform and porous CoO microprisms.Experimental results show that the CoO-200 sample exhibited superior electrocatalytic activity for water oxidation by driving a current density of 10 mA·cm-2 at a small overpotential of 280 mV in a 1.0 M KOH solution.2.A simple and rapid electrochemical deposition method was used to deposit a layer of NiSe-EA/CC film loaded on conductive carbon cloth.This simple electrodeposition methods replace the complicated process of selenization and efficiently avoid the release of toxic gases.The as-prepared NiSe-EA/CC films exhibits superior electrocatalytic activities toward both HER and OER in 1.0 M KOH solution.This electrode enables a high-performance alkaline water electrolyzer with 10 mA·cm-2 at a voltage of 1.53 V with excellent stability.