Luo Lei, Gong Zhuyu, Xu Youxun, Ma Jiani, Liu Huifen, Xing Jialiang, Tang Junwang
Key Lab of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, the Energy and Catalysis Hub, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K.
J Am Chem Soc. 2022 Jan 19;144(2):740-750. doi: 10.1021/jacs.1c09141. Epub 2021 Dec 20.
Direct and efficient oxidation of methane to methanol and the related liquid oxygenates provides a promising pathway for sustainable chemical industry, while still remaining an ongoing challenge owing to the dilemma between methane activation and overoxidation. Here, ZnO with highly dispersed dual Au and Cu species as cocatalysts enables efficient and selective photocatalytic conversion of methane to methanol and one-carbon (C1) oxygenates using O as the oxidant operated at ambient temperature. The optimized AuCu-ZnO photocatalyst achieves up to 11225 μmol·g·h of primary products (CHOH and CHOOH) and HCHO with a nearly 100% selectivity, resulting in a 14.1% apparent quantum yield at 365 nm, much higher than the previous best photocatalysts reported for methane conversion to oxygenates. In situ EPR and XPS disclose that Cu species serve as photoinduced electron mediators to promote O activation to OOH, and simultaneously that Au is an efficient hole acceptor to enhance HO oxidation to OH, thus synergistically promoting charge separation and methane transformation. This work highlights the significances of co-modification with suitable dual cocatalysts on simultaneous regulation of activity and selectivity.
将甲烷直接高效氧化为甲醇及相关液态含氧化合物为可持续化学工业提供了一条前景光明的途径，但由于甲烷活化与过度氧化之间的矛盾，这仍然是一个持续存在的挑战。在此，具有高度分散的双金属金和铜物种作为助催化剂的氧化锌，能够在室温下以氧气作为氧化剂，实现甲烷向甲醇和单碳（C1）含氧化合物的高效选择性光催化转化。优化后的AuCu-ZnO光催化剂的初级产物（CH₃OH和HCOOH）及HCHO的产量高达11225 μmol·g⁻¹·h⁻¹，选择性接近100%，在365 nm处的表观量子产率为14.1%，远高于此前报道的将甲烷转化为含氧化合物的最佳光催化剂。原位电子顺磁共振（EPR）和X射线光电子能谱（XPS）表明，铜物种作为光致电子介质促进O₂活化生成OOH，同时金是一种高效的空穴受体，可增强HO₂氧化为OH，从而协同促进电荷分离和甲烷转化。这项工作突出了用合适的双助催化剂进行共改性对同时调节活性和选择性的重要性。
