Defect- and Phase-Induced Acceleration of Electrocatalytic Hydrogen Production by Ultrathin and Small MoS₂-Decorated rGO Sheets

Abstract

Herein, development of a unique aqueous-solution-based spray drying route is presented for the preparation of novel molybdenum disulfide–reduced graphene oxide (MoS2-rGO) two-dimensional (2D) nanocomposite sheet with homogeneously dispersed 4–8 stacked 5–15 nm MoS2 sheets on rGO. The developed strategy is based on spray drying of an aqueous solution mixture of ammonium heptamolybdate, ammonium carbonate, and thiourea in the presence of suspended GO followed by calcination under H2 environment. The composite exhibit remarkable interaction between rGO and MoS2. The MoS2 contain majority of 1T phase, high density exposed active edge sites as well as strained sulfur vacancies and oxygen incorporated basal plane. In this process, ammonium carbonate takes crucial role and facilitate the formation of smaller sheets with enhanced inter layer spacing and promote the formation 1T phase. The MoS2-rGO composite exhibit excellent electrocatalytic HER activity and showed a current density of 10 mA/cm2 at 168 mV, a Tafel slope as small as 62 mV/dec, > 98% activity retention after 1000 cycles, which are quite high or comparable to that of similar compositions prepare with complicated methods. The developed protocol is simple, cheap and scalable for large-scale production and extendable for other composite materials for diverse applications.