Unveiling excitonic effect-regulated singlet oxygen generation towards efficient photocatalytic H2O2 production

Excitonic processes open up the possibility for pursuing oxygen activation and reduction in photocatalytic H2O2 production. However, the mechanistic investigation in excitonic effect-regulated reactive oxygen species (ROS) generation towards two-electron oxygen reduction reaction (2e− ORR) remains obscure. Herein, for the first time, we propose an efficient 1O2-engaged one-step two-electron O2 reduction pathway induced by the strong excitonic effect, whereby two uphill energy barriers are successfully avoided by productively changing intermediate energy levels. The intrinsic mechanism underlying the P-mediated enhanced excitonic effect was revealed by hyperfine spectroscopic and theoretical investigations, in which high-energy 1O2 was photogenerated via a nontrivial energy transfer process. As a result, the superior activity of H2O2 production was achieved due to the targeted regulation of excitonic behavior, displaying a remarkable 12.2-fold boost over pristine carbon nitride. This work not only sheds light on the role of the excitonic effect in 1O2-involved photocatalytic H2O2 production but also paves the way for optimizing exciton-based photocatalysis via atomic-scale design.