Heteroatom Modification And Performance Study Of Self-supported Cobalt Based Catalysts

In the face of the growing world energy crisis,clean energy transition has become an imminent key to development in China,including water,wind,sun,tidal energy and other new energy sources that rely on the power of nature have attracted much attention,but the use of these energy sources is still constrained by the geographical environment and other conditions.Fuel cells,secondary cells and electrolytic water reactions are the bottlenecks that need to be broken in order to make it easier to use green and clean energy.In electrochemical conversion systems,the oxygen precipitation reaction(OER),which involves a four-electron transfer process,has a high reaction energy barrier that greatly limits the energy conversion efficiency of all types of electrochemical conversion systems.Currently,the best commercially available catalysts for OER in electrolytic water are mainly doped with the noble metals Ru and Ir,which are highly efficient but less stable,and the high cost of the earth’s mineral reserves is limiting their large-scale industrial use.Therefore,the discovery of an inexpensive and simple water electrolysis catalyst with high catalytic activity and stability has become an urgent priority for the development of the energy sector in today’s society.Therefore,this study aims to develop a cheap and efficient catalyst for water electrolysis,and proposes a one-step method for the rapid implementation of heteroatomic modifications to modulate the catalyst performance based on the transition group metal element cobalt.The main contents are as follows.(1)Three-dimensional self-supported cobalt-based catalyst precursors were obtained by electrodeposition using nickel foam as the substrate.The modification of the cobalt-based catalyst by non-metallic elemental sulphur was then completed by a one-step cold quenching method of the precursor solution.The final product possesses high electrocatalytic activity and stability while retaining the original homogeneous and regular spatial structure.The product S-Co(OH)2,obtained by modulating the optimum reaction temperature during the modification process,was applied to the electrolysis of oxygen from water with an overpotential of 323 mV at a current density of 100 mA cm-2 in 1.0 M KOH and a Tafel slope of 62.5 mV dec-1,and and after 20 hours of OER catalysis at a constant potential of 1.54 V,it can still maintain about 90%of the original current density.(2)To further investigate the effect of heterogeneous atomic modifications on the electrochemical activity of cobalt-based catalysts.Based on electrochemical deposition and one-step cold quenching of the precursor solution,the effect of modifications of transition group metal elements molybdenum,vanadium and tungsten on the electrochemical activity of cobalt-based catalysts was investigated by modulating the composition of the cooled precursor solution.Again,the one-step cold quenching strategy retains the original homogeneous and regular spatial structure,and the modified samples possess high electrocatalytic activity and stability.The best performance was obtained with the molybdenum cation modification:the overpotential was only 341 mV at a current density of 100 mA cm-2 in 1.0 M KOH,with a Tafel slope of 69.0 mV dec-1,and 90%of the original current density was maintained after 24 h of OER catalysis at a constant potential of 1.54 V.