The photosynthesis of hydrogen peroxide (H2O2) from O2 and H2O using solar energy offers a sustainable alternative to conventional processes. However, the H2O2 yield is lowered because the H2O2 is decomposed by the photocatalysts that are typically used. In this study, porphyrin-containing organosilica photocatalysts were developed for efficient H2O2 production. The as-synthesized photocatalysts successfully convert O2 and H2O into H2O2 upon irradiation with visible light. Organosilica with the optimal number of porphyrin sites exhibit H2O2 production rate of 108 µmol·L-1·h-1, which is 1.8-times higher than that of the precursor porphyrin ligand. Decomposition of H2O2 by the photocatalysts was negligible. Photoluminescence measurements revealed that the incorporation of an optimal number of porphyrin sites into the organosilica significantly enhanced the photocatalytic activity for H2O2 production because of the suppression of aggregation-induced quenching. The mechanistic study revealed that H2O2 production over the porphyrin-containing organosilica photocatalysts occurred predominantly via a direct two-electron oxygen reduction reaction pathway involving singlet oxygen and photogenerated electrons. These findings open new avenues for efficient photocatalytic production of H2O2 and have significant implications for the design of advanced silica-based photocatalytic materials.
Kondo et al. (Tue,) studied this question.