Solvent-Assisted Oxygen Incorporation of Vertically Aligned MoS₂ Ultrathin Nanosheets Decorated on Reduced Graphene Oxide for Improved Electrocatalytic Hydrogen Evolution

Three-dimensional oxygen-incorporated MoS₂ ultrathin nanosheets decorated on reduced graphene oxide (O-MoS₂/rGO) had been successfully fabricated through a facile solvent-assisted hydrothermal method. The origin of the incorporated oxygen and its incorporation mechanism into MoS₂ were carefully investigated. We found that the solvent <i>N</i>,<i>N</i>-dimethylformamide (DMF) was the key as the reducing agent and the oxygen donor, expanding interlayer spaces and improving intrinsic conductivity of MoS₂ sheets (modulating its electronic structure and vertical edge sites). These O dopants, vertically aligned edges and decoration with rGO gave effectively improved double-layer capacitance and catalytic performance for hydrogen evolution reaction (HER) of MoS₂. The prepared O-MoS₂/rGO catalysts showed an exceptional small Tafel slope of 40 mV/decade, a high current density of 20 mA/cm² at the overpotential of 200 mV and remarkable stability even after 2000th continuous HER test in the acid media