Stoichiometry-driven electronic heterogeneity in covalent organic frameworks for coupled H2O2 photoproduction and chemoselective fragrance upgrading.

Coupling H2O2 photoproduction with value-added organic transformations avoids the sluggish kinetics of water oxidation, yet integrating both processes within one photocatalyst remains challenging. Here, we report stoichiometry-driven electronic heterogeneity in covalent organic frameworks (COFs) as a strategy for simultaneous H2O2 photoproduction and chemoselective fragrance upgrading. Adjusting monomer stoichiometry with distinct geometric symmetries perturbs local structural symmetry, generating electronically differentiated microenvironments within the COF skeleton. The optimized PTPD-COF1 achieves a H2O2 photosynthetic rate of 10.4 mmol g-1 h-1 in pure water, surpassing its binary analogues, and delivers coupled rates of 36.1, 53.2, and 21.6 mmol g-1 h-1 with near-quantitative, chemoselective conversion of cinnamyl, anisyl, and o-anisyl alcohols into fragrances. Theoretical analysis shows the modulated electronic environment enhances local dipole moments and lowers carrier effective masses, altering energy barriers for *OOH/*OH formation and C-H cleavage. In this work, stoichiometry-driven electronic heterogeneity is established as a design principle for multifunctional organic photocatalysts.