Dual-Type Polarization-Triggered Spontaneous Exciton Dissociation in Conjugated Polymers for Enhanced Photocatalytic...

Severe exciton effect significantly hinders free-charge-involved water redox reactions, limiting the improvement of photocatalytic performance. Herein, a dual polarization strategy was proposed to achieve spontaneous exciton dissociation while lowering exciton binding energy by introducing B←N bonds and triazine as the dual-type polarization unit into the alkynyl-linked conjugated backbone. Dual-type polarization centers can induce spontaneous exciton dissociation (exciton activation energy <25 meV) to generate more free charges that participate in water oxidation reactions. Triazine as the second polarization unit, lowers the energy barrier of the H₂O oxidation reaction and serves as the active site of the O₂ reduction reaction to accelerate H₂O₂-evolution. The H₂O₂-evolution performance of the dual-polarization photocatalyst reaches up to 4261 µmol g^-1 h^-1 with a superb apparent quantum yield of 25.84% at 420 nm and solar-to-chemical energy conversion up to 1.20% in pure water, surpassing most of the H₂O₂-evolution organic photocatalysts ever reported. Furthermore, the dual-polarization photocatalyst exhibits strong universality in complex water bodies (lake water, river water, and seawater), while achieving higher H₂O₂-evolution performance than that in pure water.