Extended Conjugation Tuning Carbon Nitride for Non-sacrificial H2O2 Photosynthesis and Hypoxic Tumor Therapy

Artificial photocatalysis offers a clean approach for producing H2O2. However, the poor selectivity and activity of H2O2 production hamper traditional industrial applications and emerging photodynamic therapy (PDT)/chemodynamic therapy (CDT). Herein, we report a C5N2 photocatalyst with a conjugated C=N linkage for selective and efficient non-sacrificial H2O2 production in both normoxic and hypoxic systems. The strengthened delocalization of pi-electrons by linkers in C5N2 downshifted the band position, thermodynamically eliminating side H-2 evolution reaction and kinetically promoting water oxidation. As a result, C5N2 had a competitive solar-to-chemical conversion efficiency of 0.55 % in overall H2O2 production and exhibited by far the highest activity under hypoxic conditions (698 mu M h(-1)). C5N2 was further applied to hypoxic PDT/CDT with outstanding performance in apparent cancer cell death and synchronous bioimaging. The study sheds light on the photosynthesis of H2O2 by carbon nitrides for health applications.