Quasi zero-dimensional MoS2 quantum dots decorated 2D Ti3C2Tx MXene as advanced electrocatalysts for hydrogen evolution reaction

Developing advanced noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) is still a great challenge. Herein, a novel HER catalyst with quasi zero-dimensional (0D) MoS2 quantum dots (QDs) supported on two-dimensional (2D) Ti3C2Tx MXene nanosheets is facilely synthesized. The MoS2 QDs/Ti3C2Tx nanohybrid retains the unique layer structure, and the MoS2 QDs are in situ formed and distributed uniformly. The obtained MoS2 QDs/Ti3C2Tx catalyst exhibits superior electrocatalytic activity due to its excellent conductivity, abundant of active sites exposed and a high percentage of 1T metallic phase (∼76%) of MoS2 QDs. Remarkably, an early HER overpotential of 220 mV at 10 mA cm−2 and a small Tafel slope of 72 mV dec−1 of MoS2 QDs/Ti3C2Tx are achieved in 0.5 M H2SO4 solution. In addition, the exchange current density of MoS2 QDs/Ti3C2Tx is ∼5 times larger compared with pure MoS2, thus demonstrating an accelerated charge transfer during the electrocatalytic process.