Gao Zhuyan, Mu Junju, Zhang Jian, Huang Zhipeng, Lin Xiangsong, Luo Nengchao, Wang Feng
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian116023, China.
University of Chinese Academy of Sciences, Beijing100049, China.
J Am Chem Soc. 2022 Oct 19;144(41):18986-18994. doi: 10.1021/jacs.2c07410. Epub 2022 Oct 10.
Photocatalytic C-C bond formation coupled with H production provides a sustainable approach to producing carbon-chain-prolonged chemicals and hydrogen energy. However, the involved radical intermediates with open-shell electronic structures are highly reactive, experiencing predominant oxidative or reductive side reactions in semiconductors. Herein, we demonstrate that hydrogen bonding on the catalyst surface and in the bulk solution can inhibit oxidation and reverse reaction of α-hydroxyethyl radicals (αHRs) in photocatalytic dehydrocoupling of ethanol over Au/CdS. Intentionally added water forms surface hydrogen bonds with adsorbed αHRs and strengthens the hydrogen bonding between αHRs and ethanol while maintaining the flexibility of radicals in solution, thereby allowing for αHRs' desorption from the Au/CdS surface and their stabilization by a solvent. The coupling rate of αHR increases by 2.4-fold, and the selectivity of the target product, 2,3-butanediol (BDO), increases from 37 to 57%. This work manifests that nonchemical bonding interactions can steer the reaction paths of radicals for selective photocatalysis.
光催化碳-碳键形成与产氢相结合为生产碳链延长的化学品和氢能提供了一种可持续的方法。然而，所涉及的具有开壳层电子结构的自由基中间体具有高反应活性，在半导体中会经历主要的氧化或还原副反应。在此，我们证明了催化剂表面和本体溶液中的氢键可以抑制乙醇在Au/CdS上进行光催化脱氢偶联反应时α-羟乙基自由基（αHRs）的氧化和逆反应。故意添加的水与吸附的αHRs形成表面氢键，并加强αHRs与乙醇之间的氢键，同时保持溶液中自由基的灵活性，从而使αHRs从Au/CdS表面解吸并通过溶剂使其稳定。αHR的偶联速率提高了2.4倍，目标产物2,3-丁二醇（BDO）的选择性从37%提高到57%。这项工作表明，非化学键相互作用可以引导自由基的反应路径以实现选择性光催化。
