Photocatalytic selective transform native lignin into valuable chemicals is an attractive but challenging task. Herein, we report a mesoporous sulfur-doped carbon nitride (MSCN-0.5) which is prepared by a facile one-step thermal condensation strategy. It is highly active and selective for the cleavage C_α−C_β bond in β−O−4 lignin model compound under visible light radiation at room temperature, achieving 99% substrate conversion and 98% C_α−C_β bond cleavage selectivity. Mechanistic studies revealed that the C_β−H bond of lignin model compounds activated by holes and generate key C_β radical intermediates, further induced the C_α−C_β bond cleavage by superoxide anion radicals (^•O₂⁻) to produce aromatic oxygenates. Waste Camellia oleifera shell (WCOS) was taken as a representative to further understand the reaction mechanisms on native lignin. 33.2 mg of monophenolic compounds (Vanillin accounted for 22% and Syringaldehyde for 34%) can be obtained by each gram of WCOS lignin, which is 2.5 times as that of the pristine carbon nitride. The present work offers useful guidance for designing metal-free heterogeneous photocatalysts for C_α−C_β bond cleavage to harvest monophenolic compounds.

光催化选择性地将天然木质素转化为有价值的化学品是一项有吸引力但具有挑战性的任务。在此，我们报告了一种通过简单的一步热冷凝策略制备的介孔硫掺杂氮化碳（MSCN-0.5）。它在室温下可见光辐射下对β-O-4木质素模型化合物中Cα-Cβ键的裂解具有高活性和选择性，实现了99%的底物转化率和98 _%的_Cα - Cβ_键裂解_选择性。机理研究表明，木质素模型化合物的 C _β -H 键被空穴激活并生成关键的 C _β自由基中间体，进一步诱导了 C _α -C_β键被超氧阴离子自由基 ( ^• O ₂ ^- ) 裂解生成芳族含氧化合物。以废油茶壳（WCOS）为代表，进一步了解天然木质素的反应机理。每克WCOS木质素可得到单酚类化合物33.2mg（香兰素占22%，丁香醛占34%），是原始氮化碳的2.5倍。_{目前的工作为设计用于 C α} -C _β键断裂以收获单酚化合物的无金属多相光催化剂提供了有用的指导