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

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.

Automated summary

Inspired by natural photosynthesis, a type-II van der Waals heterostructure photocatalyst (CdTe/B4C3) with a polarized CdTe layer integrated into a metal-free B4C3 layer was constructed, which achieved solar-driven spontaneous overall water splitting at pH = 0-7 with a high solar-to-hydrogen efficiency of 19.64%. The study found that the interlayer interaction between the CdTe and B4C3 layers in the heterostructure created an interfacial electric field enhanced by the intrinsic dipole of polarized CdTe, enabling effective separation of photogenerated carriers and enabling the hydrogen evolution reaction and oxygen evolution reaction to occur separately on the B4C3 and CdTe layers. The CdTe/B4C3 heterostructure also had suitable band edge positions to promote the redox reaction for water decomposition, due to the significant electrostatic potential difference in the heterostructure, and it triggered spontaneous redox reactions under light at pH = 0-7. This work provides guidance for the design of efficient type-II heterojunction photocatalysts for overall water splitting.