Three-Dimensional Graphene@Carbon Nanotube Aerogel-Supported Layered MoS2/Co9S8 Composite as an Efficient pH-Universal Electrocatalyst for Hydrogen Evolution

Developing high-performance non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER), which can be stably operated under various conditions is highly required in realistic production. In this work, a hierarchical architecture consisting of MoS2 and Co9S8 anchored on a reduced graphene oxide (rGO) substrate was first synthesized, then by introducing blank graphene oxide (GO) and multi-walled carbon nanotubes (CNTs), interconnected three-dimensional (3D) composite aerogels with high conductivity were obtained, showing a high activity for the HER, with low overpotentials (eta(10)) at about 90 mV (0.5 M H2SO4), 176 mV (1.0 M PBS), and 102 mV (1.0 M KOH). The high performance might be caused by special hierarchical 3D structures maximally exposing the active edges of both MoS2 and Co9S8. Additionally, 3D MoS2/Co9S8/rGO-CNTs showed a superior stability and could work stably under different conditions for more than 20 h or 1000 cycles, which is attributed to the good crystallinity after annealing, the highly symmetrical structures between Co9S8 and MoS2, and robust protection provided by the 3D carbon substrate. The results presented herein may provide an effective way to develop non-noble-metal electrocatalysts for different fields including the HER.