Dong Guang-Xing, Zhang Meng-Ran, Yuan Su-Xian, Zhang Min, Lu Tong-Bu
Institute for New Energy Materials and Low Carbon Technologies, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin, 300384, China.
Angew Chem Int Ed Engl. 2025 Aug 11;64(33):e202510993. doi: 10.1002/anie.202510993. Epub 2025 Jun 18.
The selective activation of inert C─H bonds in methanol under mild conditions to synthesize high-value C products remains a formidable challenge, primarily due to the competing high reactivity of O─H bonds. Herein, we pioneer a chlorine radical-mediated strategy to redirect the photocatalytic reaction pathway for methanol conversion toward ethylene glycol (EG). Efficient C─H bond activation is achieved by constructing a Z-scheme heterojunction photocatalyst (ZnInS/TiO-Cl) composed of chlorinated TiO (TiO-Cl) and ZnInS with efficient charge separation. Photogenerated holes in this system preferentially oxidize surface-adsorbed Cl to chlorine radicals (Cl•). These radicals drive a thermodynamically favorable hydrogen atom transfer via hydrogen abstraction, cleaving the C─H bond of methanol to form hydroxymethyl radicals (•CHOH). Subsequent C─C coupling of •CHOH intermediates, synergistically combined with a self-sustaining Cl/Cl• cycle, produces EG with exceptional selectivity (96.7%) and yield (21.6 mmol g) while suppressing overoxidation. In contrast, nonchlorinated catalysts predominantly utilize photogenerated holes for O─H bond cleavage under identical conditions, yielding only C products (HCHO, HCOOH). This work not only establishes a solar-driven approach for methanol valorization but also advances mechanistic insights into radical-mediated pathway control in heterogeneous photocatalysis.
在温和条件下选择性激活甲醇中惰性的C─H键以合成高价值C产物仍然是一项艰巨的挑战，主要是由于O─H键具有竞争性的高反应活性。在此，我们开创了一种氯自由基介导的策略，以改变甲醇转化为乙二醇（EG）的光催化反应途径。通过构建由氯化TiO（TiO-Cl）和具有高效电荷分离的ZnInS组成的Z型异质结光催化剂（ZnInS/TiO-Cl），实现了高效的C─H键活化。该体系中的光生空穴优先将表面吸附的Cl氧化为氯自由基（Cl•）。这些自由基通过氢原子提取驱动热力学上有利的氢原子转移，裂解甲醇的C─H键形成羟甲基自由基（•CHOH）。随后，•CHOH中间体的C─C偶联与自持的Cl/Cl•循环协同作用，以优异的选择性（96.7%）和产率（21.6 mmol g）生成EG，同时抑制过度氧化。相比之下，在相同条件下，非氯化催化剂主要利用光生空穴进行O─H键裂解，仅生成C产物（HCHO、HCOOH）。这项工作不仅建立了一种太阳能驱动的甲醇增值方法，还推进了对多相光催化中自由基介导途径控制的机理认识。
