The polarized electric field of CdTe/B4C3 heterostructure efficiently promotes its photocatalytic overall water splitting

Abstract

Inspired by natural photosynthesis, two-dimensional van der Waals (vdW) heterostructures are considered as promising photocatalysts for solar-driven water splitting and they attract ever-growing interest. A type-II vdW hetero-photocatalyst (CdTe/B₄C₃) integrating the polarized CdTe into metal-free B₄C₃ was constructed, which could achieve solar-driven spontaneous overall water splitting at pH = 0–7 and exhibit a high solar-to-hydrogen (STH) efficiency of 19.64%. Our calculation results show that the interlayer interaction between the CdTe and B₄C₃ monolayers in the heterostructure creates an interfacial electric field enhanced by the intrinsic dipole of polarized CdTe, which accelerates the effective separation of photogenerated carriers and makes the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) take place separately on the B₄C₃ and CdTe layers. Furthermore, the CdTe/B₄C₃ heterostructure has decent band edge positions to promote the redox reaction to decompose water due to the significant electrostatic potential difference in the CdTe/B₄C₃ heterostructure and it could trigger spontaneous redox reaction under light at pH = 0–7. This work is helpful for us to design type-II heterojunction photocatalysts with high efficiency of photogenerated carrier separation for overall water splitting.