Wu Mingyu, Zhu Juncheng, Wu Yang, Liu Siying, Zheng Kai, Wang Shumin, Li Bangwang, Li Jing, Liu Chengyuan, Hu Jun, Zhu Junfa, Pan Yang, Sun Yongfu, Xie Yi
Hefei National Research Center for Physical Science at Microscale, University of Science and Technology of China, Hefei, 230026, China.
Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Angew Chem Int Ed Engl. 2025 Jan 27;64(5):e202414814. doi: 10.1002/anie.202414814. Epub 2025 Jan 9.
Photocatalytic oxidative coupling of methane (OCM) offers an appealing route for converting greenhouse gas into valuable C hydrocarbons. However, O as the most commonly used oxidant, tends to result in inevitable overoxidation and waste of methane feedstock. Herein, we first report a photocatalytic OCM using CO as a soft oxidant for CH production under mild conditions, where an efficient photocatalyst with unique interface sites is designed and constructed to facilitate CO adsorption and activation, while concurrently boosting CH dissociation. As a prototype, the Au quantum dots anchored on oxygen-deficient TiO nanosheets are fabricated, where the Au-V-Ti interface sites for CO adsorption and activation are collectively disclosed by in situ Kelvin probe force microscopy, quasi in situ X-ray photoelectron spectroscopy and theoretical calculations. Compared with single metal site, the Au-V-Ti interface sites exhibit the lower CO adsorption energy and decrease the energy barrier of the *CO hydrogenation step from 1.05 to 0.77 eV via Au-C and Ti-O dual-site bonding. The adsorbed CO on the photocatalyst reduces the energy barrier of *CH dissociation to *CH from 2.13 to 1.59 eV, contributing to CH oxidation. Additionally, in situ Fourier-transform infrared spectroscopy unveils the Au site facilitates ethane production by engaging in *CH-Au interaction and accelerating CH-CH coupling. Thus, the photocatalyst demonstrates a high CH evolution rate of 2.60 mmol g h for OCM using CO as the soft oxidant, surpassing most of previously reported photocatalysts regardless of OCM and nonoxidative coupling of methane. This work highlights the importance of soft oxidants for improving oxidation reaction efficiency and provides atomic scale insight into the design of photocatalysts for CH conversion.
甲烷光催化氧化偶联（OCM）为将温室气体转化为有价值的碳氢化合物提供了一条有吸引力的途径。然而，氧气作为最常用的氧化剂，往往会导致不可避免的过度氧化和甲烷原料的浪费。在此，我们首次报道了一种在温和条件下使用一氧化碳作为软氧化剂进行光催化OCM以生产碳氢化合物的方法，其中设计并构建了一种具有独特界面位点的高效光催化剂，以促进一氧化碳的吸附和活化，同时促进甲烷的解离。作为原型，制备了锚定在缺氧二氧化钛纳米片上的金量子点，通过原位开尔文探针力显微镜、准原位X射线光电子能谱和理论计算共同揭示了用于一氧化碳吸附和活化的金-钒-钛界面位点。与单一金属位点相比，金-钒-钛界面位点表现出更低的一氧化碳吸附能，并通过金-碳和钛-氧双位点键合将一氧化碳加氢步骤的能垒从1.05 eV降低到0.77 eV。光催化剂上吸附的一氧化碳将甲烷解离为甲基的能垒从2.13 eV降低到1.59 eV，有助于碳氢化合物的氧化。此外，原位傅里叶变换红外光谱揭示了金位点通过参与甲基-金相互作用和加速碳-碳偶联促进乙烷的生成。因此，该光催化剂在使用一氧化碳作为软氧化剂的OCM反应中表现出2.60 mmol g⁻¹ h⁻¹的高碳氢化合物生成速率，超过了大多数先前报道的光催化剂，无论其是用于OCM还是甲烷的非氧化偶联。这项工作突出了软氧化剂对提高氧化反应效率的重要性，并为碳氢化合物转化的光催化剂设计提供了原子尺度的见解。
