Promising photocatalysts with high carrier mobility for water splitting in monolayer Ge2P4S2 and Ge2As4S2. (13th August 2019)

• Record Type: Journal Article
• Authors: Zhu, Yun-Lai; Yuan, Jun-Hui; Song, Ya-Qian; Xue, Kan-Hao; Wang, Sheng; Lian, Chen; Li, Zhao-Nan; Xu, Ming; Cheng, Xiao-Min; Miao, Xiang-Shui
• Is Part Of: International journal of hydrogen energy. Volume 44:Number 39(2019)
• Page Start: 21536
• Page End: 21545
• Publication Date: 2019-08-13
• Subjects: 2D materials -- Photocatalysts -- Direct band gap -- Carrier mobility -- Water splitting; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2019.06.068
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Monolayer Ge2 P4 S2 and Ge2 As4 S2 are proposed as a new type of efficient photocatalyst for water splitting, based on first-principles calculations. Monolayer Ge2 As4 S2 exhibits a direct band gap of 1.89 eV (based on HSE06 calculation), while monolayer Ge2 P4 S2 is an indirect gap semiconductor that can turn into direct band gap by applying 3% compressive strain. Moreover, the band edge positions of monolayer Ge2 P4 S2 and Ge2 As4 S2 perfectly cover the redox potentials of water. Remarkably, the Ge2 P4 S2 and Ge2 As4 S2 monolayers possess rather high carrier mobilities (∼10 3 –10 4 cm 2 V −1 s −1 ), and have moderate optical absorption performance in the range of visible light. In addition, the adsorption and decomposition of water molecules on monolayer Ge2 P4 S2 and Ge2 As4 S2 are explored to illustrate the mechanism of photocatalytic hydrogen formation. These results demonstrate that the monolayer Ge2 P4 S2 and Ge2 As4 S2 hold great potential for photocatalytic water splitting. Graphical abstract: Image 1 Highlights: Monolayer Ge2 As4 S2 and Ge2 P4 S2 show considerable light absorption. Suitable band gaps and band alignments benefit photolytic water splitting. Strain can tune the indirect band structure of Ge2 P4 S2 to direct. High carrier mobilities well separate photogenerated electrons and holes.