Chemical Vapor Deposition Grown Large-Scale Atomically Thin Platinum Diselenide with Semimetal-Semiconductor Transition.

Among two-dimensional (2D) transition-metal dichalcogenides (TMDCs), platinum diselenide (PtSe2) stands in a distinct place due to its fancy transition from type-II Dirac semimetal to semiconductor with a thickness variation from bulk to monolayer (1 ML) and the related versatile applications especially in mid-infrared detectors. However, achieving atomically thin PtSe2 is still a challenging issue. Herein, we have designed a facile chemical vapor deposition (CVD) method to achieve the synthesis of atomically thin 1T-PtSe2 on an electrode material of Au foil. Thanks to the high crystalline quality, we have confirmed the complete transition from semimetal to semiconductor from trilayer (3 ML) to 1 ML 1T-PtSe2. More importantly, we have found that such atomically thin 1T-PtSe2 can serve as perfect electrocatalysts, featured with a record high hydrogen evolution reaction (HER) efficiency (comparable to traditional Pt catalyst). Our work is helpful toward the large-scale synthesis, exotic physical property exploration, and intriguing application development of atomically thin TMDCs.