MoS2 quantum dot-decorated MXene nanosheets as efficient hydrogen evolution electrocatalysts

2D MXene nanosheets are regarded as promising cathode catalysts towards the hydrogen evolution reaction (HER), while their overall electrocatalytic ability still needs to be optimized before the practical application. In this contribution, we put forward a controllable assembly approach for constructing a heterostructured nanoarchitecture made from ultrafine MoS2 quantum dot-decorated Ti3C2Tx MXene nanosheets (MQDs/Ti3C2Tx). Benefiting from the remarkable structural features of the ultrathin catalyst layers, homogeneous MoS2 distribution, optimized electronic structure, and good electron conductivity, the resulting MQD/Ti3C2Tx catalyst exhibits superior HER properties with a low onset potential of 66 mV, a small Tafel slope of 74 mV dec−1, and a long lifespan, in contrast to the insufficient HER ability for bare MoS2 quantum dots and Ti3C2Tx itself. DFT calculations further disclose the optimized band structure of the MQDs/Ti3C2Tx model with numerous diverse active sites, which play fundamental roles in boosting the HER kinetics.