Dual-Type Polarization-Triggered Spontaneous Exciton Dissociation in Conjugated Polymers for Enhanced Photocatalytic H(2)O(2) Evolution in Pure Water.

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 HO oxidation reaction and serves as the active site of the O reduction reaction to accelerate HO-evolution. The HO-evolution performance of the dual-polarization photocatalyst reaches up to 4261 µmol g h 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 HO-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 HO-evolution performance than that in pure water.