Graphene-reinforced metal-organic frameworks derived cobalt sulfide/carbon nanocomposites as efficient multifunctional electrocatalysts

摘要

Developing cost-effective electrocatalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is vital in energy conversion and storage applications.Herein,we report a simple method for the synthesis of graphene-reinforced CoS/C nanocomposites and the evaluation of their electrocatalytic performance for typical electrocatalytic reactions.Nanocomposites of CoS embedded in N,S co-doped porous carbon and graphene(CoS@C/Graphene)were generated via simultaneous sulfurization and carbonization of one-pot synthesized graphite oxide-ZIF-67 precursors.The obtained CoS@C/Graphene nanocomposites were characterized by X-ray diffraction,Raman spectroscopy,thermogravimetric analysis-mass spectroscopy,scanning electronic microscopy,transmission electronic microscopy,X-ray photoelectron spectroscopy and gas sorption.It is found that CoS nanoparticles homogenously dispersed in the in situ formed N,S co-doped porous carbon/graphene matrix.The CoS@C/10Graphene composite not only shows excellent electrocatalytic activity toward ORR with high onset potential of 0.89 V,four-electron pathway and superior durability of maintaining 98%of current after continuously running for around 5 h,but also exhibits good performance for OER and HER,due to the improved electrical conductivity,increased catalytic active sites and connectivity between the electrocatalytic active CoS and the carbon matrix.This work offers a new approach for the development of novel multifunctional nanocomposites for the next generation of energy conversion and storage applications.