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

Graphical A three-dimensional composite is synthesized by a simple two-step method and applied as a highly active pH-universal electrocatalyst for the hydrogen evolution reaction. The material is stable in acid, neutral, and alkaline media. 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 MoS 2 and Co 9 S 8 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 (η 10 ) at about 90 mV (0.5 M H 2 SO 4 ), 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 MoS 2 and Co 9 S 8 . Additionally, 3D MoS 2 /Co 9 S 8 /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 Co 9 S 8 and MoS 2 , 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.