Regulation of Excited-State Dynamics via Cyano-Functionalization in Fused Aromatic Unit-Based Conjugated Polymers for Efficient Photocatalytic H2O2 Production from Air and Water

Abstract

The production of hydrogen peroxide (H2O2) from water and oxygen by artificial photosynthesis using semiconductor photocatalysts has become an effective method for converting solar energy into chemical energy. However, due to the low separation efficiency of electron-hole pairs and the short excited-state lifetime, most reported materials exhibit heavy reliance on the high concentration of O2 and sacrificial agents. Herein, two fused aromatic unit-based conjugated polymers are designed to challenge this issue. For further regulating the excited-state dynamics, the cyano-functionalization strategy is proposed. A series of experimental and theoretical investigations verify that the fused aromatic units can effectively stabilize the excited state, and the cyano groups are beneficial in enhancing light harvesting, prolonging excited-state lifetime, and promoting charge separation. In addition, the cyano-functionalization could also lead to enhanced O2 adsorption and hydrophilicity. Owing to these advantages, under visible light irradiation, the cyano-functionalized sample P-CN exhibits excellent photocatalytic H2O2 production performance from air and pure water without any sacrificial agents.