MoS_2 Formed on Mesoporous Graphene as a Highly Active Catalyst for Hydrogen Evolution

摘要

A highly active and stable electrocatalyst for hydrogen evolution is developed based on the in situ formation of MoS_2 nanoparticles on mesoporous graphene foams (MoS_2/MGF). Taking advantage of its high specific surface area and its interconnected conductive graphene skeleton, MCF provides a favorable microenvironment for the growth of highly dispersed MoS_2 nanoparticles while allowing rapid charge transfer kinetics. The MoS_2/MCF nanocomposites exhibit an excellent electrocatalytic activity for the hydrogen evolution reaction with a low overpotential and substantial apparent current densities. Such enhanced catalytic activity stems from the abundance of catalytic edge sites, the increase of electrochemically accessible surface area and the unique synergic effects between the MCF support and active catalyst. The electrode reactions are characterized by electrochemical impedance spectroscopy. A Tafel slope of ≈ 42 mV per decade is measured for a MoS_2/ MCF modified electrode, suggesting the Volmer-Heyrovsky mechanism of hydrogen evolution.