Polarization-direction-controlled Z-scheme photocatalytic switch in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>Sc</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>CO</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mrow><mml:mi>Pt</mml:mi><mml:mi mathvariant="normal">S</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math> heterostructures: A first-principles study
Yu Zhang, Yanqing Shen, Lingling Lv, Min Zhou, Xin Yang, Xianghui Meng, Nan Zhang, Kexin Wang, Bing Zhang, Zhongxiang Zhou
Abstract
Constructing van der Waals (vdW) heterostructures is the most commonly used method for separating photogenerated carriers, which can effectively improve photocatalytic water-splitting efficiency. Although many vdW heterostructure photocatalysts have been proposed, there is still a lack of effective strategies to regulate the photocatalytic reaction ability. In this work, we propose a ${\mathrm{Sc}}_{2}{\mathrm{CO}}_{2}/{\mathrm{Pt}\mathrm{S}}_{2}$ heterostructure that can achieve the photocatalytic switch with different polarization directions (P \ensuremath{\uparrow} and P \ensuremath{\downarrow}). Both the P \ensuremath{\uparrow} and P \ensuremath{\downarrow} ${\mathrm{Sc}}_{2}{\mathrm{CO}}_{2}/{\mathrm{Pt}\mathrm{S}}_{2}$ heterostructures are semiconductors with type-II band-edge distribution. Remarkably, through the analysis of band arrangement and the built-in electric field, we found two completely different carrier-migration mechanisms inside the two heterostructures. The ${\mathrm{Sc}}_{2}{\mathrm{CO}}_{2}/{\mathrm{Pt}\mathrm{S}}_{2}$ heterostructure with P \ensuremath{\uparrow} can be used as a direct Z-scheme photocatalyst, showing great application prospect for water splitting. In contrast, the P \ensuremath{\downarrow} ${\mathrm{Sc}}_{2}{\mathrm{CO}}_{2}/{\mathrm{Pt}\mathrm{S}}_{2}$ heterostructure cannot undergo photocatalytic reactions affected by the direction of the built-in electric field. Therefore, based on ${\mathrm{Sc}}_{2}{\mathrm{CO}}_{2}/{\mathrm{Pt}\mathrm{S}}_{2}$ heterostructure, the ``on'' and ``off'' of photocatalysis are successfully achieved in a single material. Additionally, Gibbs free-energy calculation, high light absorption, and strain tunable band gap indicate that the ${\mathrm{Sc}}_{2}{\mathrm{CO}}_{2}/{\mathrm{Pt}\mathrm{S}}_{2}$ heterostructure is a promising candidate for photocatalytic applications.