Alternate to Molybdenum Disulfide: A 2D, Few‐Layer Transition‐Metal Thiophosphate and Its Hydrogen Evolution Reaction Activity over a Wide pH Range

A two‐dimensional, few‐layer nickel thiophosphate, NiPS3, was introduced as a hydrogen evolution reaction catalyst from aqueous acidic, alkaline, and neutral solutions. NiPS3 is semiconducting in nature, and its band structure calculations revealed the importance of the [P2S6]4− units in the adsorption of hydrogen and subsequent evolution. Onset potentials of −0.062, −0.065, and −0.298 V versus RHE were observed in acidic, alkaline, and neutral media. Tafel slopes of 55, 48, and 94 mV dec−1 and exchange current densities of 1.8×10−4, 6.1×10−4, and 3.2×10−5 A cm−2 were observed in aqueous 0.5 m H2SO4, 1 m KOH, and 3.5 % NaCl solutions, respectively. The catalyst was found to be very stable, and the constituting elements are earth abundant. The present study opens up a new class of semiconducting layered materials to catalyze various redox reactions. Achieving a single layer will be of great interest to electrical and magnetic devices.