Exciton regulation in organic photocatalysts toward efficient H2O2 generation: a mini review

Abstract

Photocatalytic technology provides a direct and sustainable approach for converting solar energy into chemical energy. The photocatalytic production of hydrogen peroxide (H2O2) directly from air and water is both environmentally friendly and economically feasible. Organic photocatalysts have garnered considerable attention due to their tunable molecular structures and metal-free compositions. To overcome the inherent challenge of exciton dissociation in organic systems, this review highlights three key strategies: substituting polar functional groups, extending π-conjugated frameworks, and constructing donor-acceptor (D-A) structures. These approaches enhance intramolecular dipole moments, improve excited-state electron delocalization, and enhance the internal electric field (IEF) to drive directional exciton separation, ultimately improving H2O2 production efficiency. In addition, the study detailed the use of temperature-dependent photoluminescence, transient absorption spectroscopy, or TD-DFT calculations to elucidate exciton dissociation; Kelvin probe force microscopy to evaluate the strength of the IEF; and rotating disk electrode experiments, 18O isotope labeling, or in-situ FTIR spectroscopy to determine the pathways of H2O2 formation. Finally, future perspectives are proposed, emphasizing quantitative analyses of excited states and ground states, development of self-floating and photothermal catalysts, and AI-assisted activity prediction. This work provides theoretical insights and technical guidance for advancing the sustainable photocatalytic synthesis of H2O2.