Cd Single Atom as an Electron Mediator in an S-Scheme Heterojunction for Artificial Photosynthesis of H2O2

Abstract

Developing conductor-mediated S-scheme heterojunction photocatalysts imitating natural photosynthetic systems emerges as a promising approach to hydrogen peroxide (H₂O₂) production. However, achieving precise coupling between two semiconductors with a charge shuttle and modulating the interfacial interactions still remain a significant bottleneck. Herein, we propose a catalyst architecture with a Cd single atom mediated S-scheme heterojunction formed by interfacing CdS and TiO₂ nanoparticles. This catalyst exhibits an H₂O₂ production rate as high as 60.33 µmol g⁻¹ min⁻¹ under UV–vis light irradiation, which is attributed to the efficient charge transport at the interface of CdS and TiO₂ thanks to the Cd single atom mediated S-scheme. In-situ X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) spin-trapping tests confirm the S-scheme charge transfer route. Femtosecond transient absorption (fs-TA) spectroscopy and other ex-situ characterizations further corroborate the efficient charge transport across the catalyst interface. This work offers a new perspective on constructing single atoms mediated heterojunctions to enhance photocatalytic performance.