Plasma-Induced Exfoliation Provides Onion-Like Graphene-Surrounded MoS₂ Nanosheets for a Highly Efficient Hydrogen Evolution Reaction

Abstract

With the goal of obtaining sustainable earth-abundant electrocatalyst materials displaying high performance in the hydrogen evolution reaction (HER), here we propose a facile one-pot plasma-induced electrochemical process for the fabrication of new core-shell structures of ultrathin MoS₂ nanosheets engulfed within onion-like graphene nanosheets (OGNs@MoS₂). The resultant OGNs@MoS₂ structures not only increased the number of active sites of the semiconducting MoS₂ nanosheets but also enhanced their conductivity. Our OGNs@MoS₂ composites exhibited high HER performance, characterized by a low overpotential of 118 mV at a current density of 10 mA cm^-2, a Tafel slope of 73 mV dec^-1, and long-time stability of 10⁵ s without degradation; this performance is much better than that of the sheet-like graphene-wrapped MoS₂ composite GNs@MoS₂ (182 mV, 82 mV dec^-1) and is among the best ever reported for composites involving MoS₂ and graphene nanosheets prepared through a simple one-batch process and using a low temperature and a short time for the HER. This approach appears to be an effective and simple strategy for tuning the morphologies of composites of graphene and transition metal dichalcogenide materials for a broad range of energy applications.