Electrochemical energy storage and conversion processes are closely related to electrocatalysts,but the scarcity of precious metal reserves and uneconomical prices have seriously hindered the large-scale commercial application of precious metal catalysts.Multifunctional catalysts can perform multiple efficient catalytic reactions in the same electrolyte,with higher catalytic performance and lower preparation cost.Therefore,it is crucial to develop efficient and low-cost multifunctional electrocatalysts to replace noble metal catalysts.In this work,non-precious metal bifunctional electrocatalysts derived from two MOFs materials were prepared.The main research contents are as follows:1.In this study,a chemical synthesis method to effectively improve the catalytic performance is proposed.As the main ingredient of waste lithium battery polluting the environment,Li Fe PO4can be used as an ideal Fe source and P source to construct Carbon-based bifunctional electrocatalyst materials with MOFs.This cobalt-iron bimetallic nitrogen-phosphorus co-doped meterial can be applied to oxygen evolution reaction(OER)and oxygen reduction reaction(ORR),which can achieve the purpose of reducing harmful waste and turning waste into treasure.The active sites of P-ZIF-67/LFP-2:1 are mainly Co Fe and Co2P nanoparticles.For OER performance,the catalyst exhibits good electrocatalytic performance with an overpotential of 321.2 m V at a current density of 10 m A cm-2.After 8 hours of stability test,the current retention rate of P-ZIF-67/LFP-2:1 reaches 94.27%,which is better than that of commercial Ir O2catalyst.For ORR performance,the half-wave potential reaches 0.82 V.When we applied it to ZABs,the assembled Zn-air battery exhibited a peak power density of 271.1 m W cm-2,which was superior to the ZAB with noble metal catalysts(216.8 m W cm-2).After a 200-hour charge-discharge test,it showed negligible potential change.The emergence of this new type of material can not only reduce the environmental burden caused by the subsequent mass scrapping of lithium batteries,but also provide new ideas for the development of new catalyst materials.2.We attempted to simultaneously introduce three metals,Ni,Fe,and Co on nickel foam by one-step solvothermal method,and prepared a catalyst material(Ni Fe Co-MOF/NF)with the structure of supporting amorphous MOF on nickel foam.Compared with the bimetallic Ni Fe-MOF/NF,it is improved in terms of OER performance,at a current density of 10 m A cm-2,the overpotential is reduced to 284.0 m V with the Tafel slope of 82.4 m V dec-1.After an 8-hour stability test,Ni Fe Co-MOF/NF only observes a current decay of about 1.3%,and the current retention rate is as high as 98.7%,which is better than commercial noble metal catalysts.For the hydrogen evolution reaction(HER)performance,the overpotential of Ni Fe Co-MOF/NF is reduced to 237.0 m V at a current density of 10 m A cm-2,which is 49.0 m V lower than that of Ni Fe-MOF/NF.After an 8-hour stability test,the current retention rate of Ni Fe Co-MOF/NF reached 95.7%.In summary,the emergence of this new material has brought hope to improve the conversion efficiency of water electrolysis devices and to realize efficient and stable hydrogen production as soon as possible.This work provides a feasible strategy for rational design and low-cost synthesis of efficient and durable OER/HER bifunctional catalysts. |