Synergistically Coupling Phosphorus-Doped Molybdenum Carbide with MXene as a Highly Efficient and Stable Electrocatalyst for Hydrogen Evolution Reaction

Developing low-cost and highly efficient hydrogen evolution reaction (HER) electrocatalysts is an important research area for large-scale hydrogen production. Herein, we report a new nanohybrid consisting of phosphorus-doped molybdenum carbide nanodots supported on Ti3C2 flakes encapsulated by nitrogen-doped carbon (denoted as P-Mo2C/Ti3C2@NC), which can serve as a high-performance nonprecious-metal electrocatalyst for HER. The inherent anchoring sites of the conductive Ti3C2 matrix contribute to the perfect distribution and confined growth of the electrocatalytically active P-doped Mo2C nanodots, thereby constructing optimized interfacial coupling between the P-doped Mo2C nanodots and the conductive Ti3C2 matrix. Meanwhile, nitrogen-doped porous carbon shells can stabilize the Ti3C2 flakes against spontaneous oxidation. Thus, a synergetic effect of collaborative catalytic interfaces between Ti3C2 and ultrasmall P-Mo2C nanodots encapsulated by nitrogen-doped porous carbon and an appropriate introduction of a Ti3C2 substance afford overall enhancement in electrical conductivity and exposure of reactive sites. As a result, the P-Mo2C/Ti3C2@NC nanohybrid catalyst exhibits remarkable HER activity with an overpotential of 177 mV at 10 mA cm-2, fast reaction kinetics of 57.3 mV dec-1, and long-term stability over 60 h in the acidic electrolyte, which exceed the P-Mo2C@NC, Ti3C2@NC, P-Mo2C/CNT@NC, and P-Mo2C/rGO@NC nanohybrids. This work paves the way for the development of advanced MXenes-based electrocatalysts for HER and also inspires the exploration of a new branch of MXene-based nanohybrids for renewable energy applications.