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Edited by Alexis T. Bell, University of California, Berkeley, approved on October 25, 2021 (review received on August 10, 2021)

Due to the dielectric confinement effect in the ultra-thin two-dimensional photocatalyst, the exciton effect derived from the Coulomb interaction between photogenerated electrons and holes can be significantly promoted, which will make the system have different light excitation scenarios. A major challenge is to achieve non-trivial exciton modulation, especially for inorganic semiconductors, to efficiently use solar energy. This study proposes a strategy to modify the electronic and surface structure caused by surface Pt dopants to enhance the tendency to generate 1O2 through triplet energy transfer. This design concept highlights a promising exciton control strategy in two-dimensional inorganic semiconductors and proves the importance of impurity states in the energy transfer process.

Due to the reduction of dielectric shielding, the exciton effect should be considered in the ultra-thin two-dimensional photocatalyst, and achieving non-trivial exciton adjustment is a major challenge. However, the influence of structural modification on the regulation of excitons is still at a relatively early stage. Here, we report the abnormal effect of surface replacement doping with Pt on the electronic and surface properties of the Bi3O4Br atomic-level thin layer, thereby enhancing the tendency to generate 1O2. In terms of electronics, the introduced Pt impurity state with a lower energy level can trap the light-induced singlet excitons, thereby reducing the singlet-triplet energy gap by about 48%, and effectively promoting the crossover process between systems, thereby Obtain an effective yield of triplet excitons. On the surface, the chemisorption state of O2 leads to changes in the magnetic moment (ie spin state) of O2 through electron-mediated triplet energy transfer, which leads to a spin reversal process and highly specific 1O2 generation. These characteristics reflect the opportunity for surface engineering to provide unique strategies for exciton regulation, and will stimulate more research on exciton-triggered photocatalysis for solar energy conversion.

↵1D.Z., PW and JW made the same contribution to this work.

Author contributions: DZ, PW and SZ design research; DZ conducted research; DZ, JW, YL and YX analysis data; and DZ, PW and SZ wrote this paper.

The author declares no competing interests.

This article is directly contributed by PNAS.

This article contains online support information https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2114729118/-/DCSupplemental.

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