Abstract
Circumventing the conventional two-electron oxygen reduction pathway remains a great problem in enhancing the efficiency of H(2)O(2) photosynthesis. A promising approach to achieve outstanding photocatalytic activity involves the utilization of redox intermediates. Here, we engineer a polyimide aerogel photocatalyst with photoreductive carbonyl groups for non-sacrificial H(2)O(2) production. Under photoexcitation, carbonyl groups on the photocatalyst surface are reduced, forming an anion radical intermediate. The produced intermediate is oxidized by O(2) to produce H(2)O(2) and subsequently restores the carbonyl group. The high catalytic efficiency is ascribed to a photocatalytic redox cycle mediated by the radical anion, which not only promotes oxygen adsorption but also lowers the energy barrier of O(2) reduction reaction for H(2)O(2) generation. An apparent quantum yield of 14.28% at 420 ± 10 nm with a solar-to-chemical conversion efficiency of 0.92% is achieved. Moreover, we demonstrate that a mere 0.5 m(2) self-supported polyimide aerogel exposed to natural sunlight for 6 h yields significant H(2)O(2) production of 34.3 mmol m(-2).