Phosphorus-doped molybdenum carbide/MXene hybrid architectures for upgraded hydrogen evolution reaction performance over a wide pH range

Annealing atmosphere strongly affects the structure of phosphorus-doped molybdenum carbide (P-Mo2C) nanodots hybridized with Ti3C2 MXene flakes and modulates its performance in the hydrogen evolution reaction. It is discovered that the nanohybrids undergo partial oxidation when they are annealed in N2, while retaining similar nanostructures when they are annealed in H2/Ar, Ar, and NH3. More importantly, compared with the nanohybrids annealed in Ar, NH3, and N2, the nanohybrid annealed in H2/Ar delivers the best HER performances, which delivers overpotentials (η10) of 172 and 219 mV at 10 mA cm−2, and Tafel slopes of 56.2 and 63.3 mV dec−1 in 0.5 M H2SO4 and 1.0 M KOH, respectively. The excellent HER performance could be attributed to optimal P-Mo2C nanodots for more accessible reactive sites, highly conductive Ti3C2 matrix for accelerated electron transfer, as well as N-doped carbon for more active centers. This work may shed light on developing the promising MXenes-based electrocatalysts by manipulating annealing atmosphere.