Biomass depolymerization is a strategic choice for achieving sustainable development and producing high-value aromatic chemicals. Recently, photocatalysis has attracted widespread attention for efficient cleavage of C-O bonds in lignin under mild conditions. However, common inorganic semiconductors photocatalyst often suffer from several drawbacks, such as low solar light utilization efficiency, easily photogenerated carrier recombination and so on. Here, we synthesized a novel organic semiconductor material dipyrenylmercapto perylenediimide (DPPDI), which exhibited exceptional light absorption capabilities and remarkable electron mobility attributed to its planar structure. An organo-inorganic heterojunction photocatalyst was prepared by cooperating DPPDI with TiO₂, which was used for efficient and selective cleavage of C_α-O bonds in lignin model compounds benzyl phenyl ether (BPE). Under the optimized conditions, the Pd@5%DPPDI/TiO₂ photocatalyst can achieve complete conversion of substrate BPE within 30 min, and the C-O bond cleavage selectivity reached ~100%, which was 2 times higher than that of commercial Pd@TiO₂. After four cycles, the conversion rate of BPE exhibited exceptional cycling stability with only a marginal 10% decrease. The experimental and theoretical calculations proved that this DPPDI/TiO₂ heterojunction photocatalyst not only extended the light absorption wavelength range but also mitigated recombination of photogenerated carriers, which increased the efficiency of photocatalysis. This work shows the potential application of organo-inorganic heterojunction photocatalyst based perylenediimide in the field of biomass photocatalytic depolymerization.

perylenediimide; organic-inorganic heterojunction photocatalyst; photocatalysis; lignin; cα-o bond cleavage.