Phase Modulation and Chemical Activation of MoSe2 by Phosphorus for Electrocatalytic Hydrogen Evolution Reaction

Molybdenum diselenide (MoSe 2 ), as a member of transitional metal chalcogenides (TMDs), is regarded as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its intrinsic performance is still hampered by insufficient exposure of active sites and inferior electric conductivity. The phase‐engineered synthesis of stable metallic 1T‐MoSe 2 with abundant active sites is thus highly desirable for further boosting HER performance. Herein, a phosphorus (P)‐doped MoSe 2 with controlled 2H/1T heterophases is synthesized through a facile way. Combining calculations and experiments, it is demonstrated that the doping of P (≈0.83 wt%) not only induces a phase change from 2H to 1T, but activates the Se atoms in the basal plane, thereby significantly enhancing its intrinsic HER performance. An overpotential of 174 mV is achieved at the benchmark of 10 mA cm −2 with a Tafel slope of 51 mV dec −1 . More importantly, after the long‐term run at 180 mV for 10 h, the P‐1T/2H‐MoSe 2 still displays a high current density of 10.43 mA cm −2 and keeps its original 2H/1T heterostructures, showing superior electrochemical stability and structural robustness. This work provides a facile method for improving the intrinsic HER activity of MoSe 2 through nonmetal doping, which helps to understand the activity origin of MoSe 2 .