Non-noble Metal Catalysts For Water Electrolysis And Zinc-air Batteries

Electrochemical energy conversion is an efficient and clean energy conversion method.In devices such as electrolyzed water,fuel cells,and metal-air battery devices,the electrochemical reactions that occur can effectively achieve bidirectional conversion between chemical energy and electrical energy.The hydrogen evolution reactions?HER?,oxygen evolution reactions?OER?,and oxygen reduction reactions?ORR?involved in these energy conversion devices require highly efficient catalysts to accelerate the reaction rate to improve energy conversion efficiency.Traditionally effective precious metal catalysts such as Pt or RuO₂ cannot be widely applied due to problems such as high price and limited reserves.Therefore,it is of great significance to develop and prepare an efficient,stable and cheap electrocatalyst.The electrocatalyst needs to meet the following elements:a porous structure with a high specific surface area;high electrical conductivity;heterojunction multi-element composite structure;synergistic effects of heteroatom doping.Based on the above considerations,several electrocatalysts were prepared and their electrocatalytic activity was studied.The specific work is as follows:First,using MoO₃ nanorods as a template and a molybdenum source,ZIF-67 is loaded on its surface to obtain a MoO₃@ZIF-67 precursor,and a CoMoO₄ nanotube structure material is prepared.This hollow tube structure has a large specific surface area.The synergistic effect between Co and Mo promotes OER catalytic activity.It only needs 315 mV overpotential to achieve a current density of 10 mA cm^-2,showing good OER.catalytic activity.Secondly,ZIF-67 was loaded on the surface of the MoO₃ nanorods to obtain the MoO₃@ZIF-67 precursor,which was calcined and carburized,and then hydrothermally vulcanized to prepare the MoO₂@MoS₂@Co₉S₈ ternary composite heterojunction.In 1 M KOH solution,the material showed good catalytic activity for both HER and OER reactions.The synergistic effect between MoS₂ and Co₉S₈ can promote the catalytic activity.The material has dual-function catalytic activity and is expected to be used in water electrolysis.Finally,using ZIF-8 as a precursor,thioacetamide was used to sulfide it,and the vulcanized material was calcined and carburized in nitrogen to obtain a ZnS modified N,S co-doped porous polyhedral carbon material.The porous carbon matrix can effectively promote the charge and substance transport,a small amount of ZnS can modify the electronic structure of the material,and the co-doping of N and S effectively promotes the ORR catalytic activity.The ZnS@NC-3 sample with a 3 minute vulcanization reaction showed good ORR catalytic activity.Load it on the air cathode to assemble a zinc-air battery.The battery has an open circuit voltage of 1.524 V and a power density of 176 mW cm^-2,showing good battery performance.