Boosting the Hydrogen Evolution Reaction Performance of P-Doped PtTe 2 Nanocages via Spontaneous Defects Formation.

PtTe 2 , a member of the noble metal dichalcogenides (NMDs), has aroused great interest in exploring its behavior in the hydrogen evolution reaction (HER) due to the unique type-II topological semimetallic nature. In this work, a simple template-free hydrothermal method to obtain the phosphorus-doped (P-doped) PtTe 2 nanocages with abundant amorphous and crystalline interface (A/C-P-PtTe 2 ) is developed. Revealed by density functional theory calculations, the atomic Te vacancies can spontaneously form on the basal planes of PtTe 2 by the P doping, which results in the unsaturated Pt atoms exposed as the active sites in the amorphous layer for HER. Owing to the defective structure, the A/C-P-PtTe 2 catalysts have the fast Tafel step determined kinetics in HER, which contributes to an ultralow overpotential (η = 28 mV at 10 mA cm -2 ) and a small Tafel slope of 37 mV dec -1 . More importantly, benefiting from the inner stable crystalline P-PtTe 2 nanosheets, limited decay of the performance is observed after chronopotentiometry test. This work reveals the important role of the inherent relationship between structure and activity in PtTe 2 for HER, which may bring another enlightenment for the design of efficient catalysts based on NMDs in the near future.