Atomic-Layer Controlled Interfacial Band Engineering at Two-Dimensional Layered PtSe<sub>2</sub>/Si Heterojunctions for Efficient Photoelectrochemical Hydrogen Production
Cheng‐Chu Chung, Han Yeh, Po‐Hsien Wu, Cheng‐Chieh Lin, Chia‐Shuo Li, Tien-Tien Yeh, Yi Chou, Chuan‐Yu Wei, Cheng‐Yen Wen, Yi‐Chia Chou, Chih‐Wei Luo, Chih‐I Wu, Ming‐Yang Li, Lain‐Jong Li, Wen‐Hao Chang, Chun‐Wei Chen
Abstract
Platinum diselenide (PtSe2) is a group-10 two-dimensional (2D) transition metal dichalcogenide that exhibits the most prominent atomic-layer-dependent electronic behavior of “semiconductor-to-semimetal” transition when going from monolayer to bulk form. This work demonstrates an efficient photoelectrochemical (PEC) conversion for direct solar-to-hydrogen (H2) production based on 2D layered PtSe2/Si heterojunction photocathodes. By systematically controlling the number of atomic layers of wafer-scale 2D PtSe2 films through chemical vapor deposition (CVD), the interfacial band alignments at the 2D layered PtSe2/Si heterojunctions can be appropriately engineered. The 2D PtSe2/p-Si heterojunction photocathode consisting of a PtSe2 thin film with a thickness of 2.2 nm (or 3 atomic layers) exhibits the optimized band alignment and delivers the best PEC performance for hydrogen production with a photocurrent density of −32.4 mA cm–2 at 0 V and an onset potential of 1 mA cm–2 at 0.29 V versus a reversible hydrogen electrode (RHE) after post-treatment. The wafer-scale atomic-layer controlled band engineering of 2D PtSe2 thin-film catalysts integrated with the Si light absorber provides an effective way in the renewable energy application for direct solar-to-hydrogen production.