Rational design of dibenzothiophene-S,S-dioxide-containing conjugated polymers for highly efficient photosynthesis of hydrogen peroxide in pure water

Abstract

Artificial photosynthesis is an ideal sustainable route for hydrogen peroxide (H₂O₂) production via a mild, clean, and low-cost process. The incorporation of nitrogen-containing building blocks into the material has an obvious impact on the performance toward photocatalytic H₂O₂ production. Herein, we design and synthesize three novel conjugated polymers from dibenzothiophene-S,S-dioxide as the electron-deficient unit and benzene analogues with a varying number of nitrogen atoms as building blocks. The photoelectric and surface properties of the obtained polymers could be easily tailored by controlling the nitrogen content in the framework, thus resulting in an increased charge transfer and separation ability, broader visible light absorption range, optimal energy level and enhanced water dispersibility. In addition, nitrogen atoms might be active sites for the photocatalytic reaction to improve H₂O₂ production efficiency. Among these polymers, PSO-BN2 exhibited the best photocatalytic performance with an exceptionally high H₂O₂ production rate of 6996 μmol h⁻¹ g⁻¹ in pure water without any sacrificial reagent. To the best of our knowledge, this is one of the highest photocatalytic H₂O₂ production efficiencies reported for conjugated polymeric photocatalysts and organic–inorganic heterojunction photocatalysts so far. Mechanism studies reveal that the incorporation of pyrazine modified the photocatalytic H₂O₂ generation pathway, allowing dual channels to accelerate the overall H₂O₂ production rate.