Breaking the Activity-Selectivity Trade-off for CH 4 -to-C 2 H 6 Photoconversion

• Published in: Journal of the American Chemical Society 2024-05, Vol.146 (17), p.12233-12242
• Main Authors: Zheng, Kai, Wu, Mingyu, Zhu, Juncheng, Zhang, Wei, Liu, Siying, Zhang, Xiaojing, Wu, Yang, Li, Li, Li, Bangwang, Liu, Wenxiu, Hu, Jun, Liu, Chengyuan, Zhu, Junfa, Pan, Yang, Zhou, Meng, Sun, Yongfu, Xie, Yi
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.4c03546

Photocatalytic conversion of methane (CH ) to ethane (C H ) has attracted extensive attention from academia and industry. Typically, the traditional oxidative coupling of CH (OCM) reaches a high C H productivity, yet the inevitable overoxidation limits the target product selectivity. Although the traditional nonoxidative coupling of CH (NOCM) can improve the product selectivity, it still encounters unsatisfied activity, arising from being thermodynamically unfavorable. To break the activity-selectivity trade-off, we propose a conceptually new mechanism of H O -triggered CH coupling, where the H O -derived ·OH radicals are rapidly consumed for activating CH into ·CH radicals exothermically, which bypasses the endothermic steps of the direct CH activation by photoholes and the interaction between ·CH and ·OH radicals, affirmed by characterization techniques, femtosecond transient absorption spectroscopy, and density-functional theory calculation. By this pathway, the designed Au-WO nanosheets achieve unprecedented C H productivity of 76.3 mol mol h with 95.2% selectivity, and TON of 1542.7 (TOF = 77.1 h ) in a self-designed flow reactor, outperforming previously reported photocatalysts regardless of OCM and NOCM pathways. Also, under outdoor natural sunlight irradiation, the Au-WO nanosheets exhibit similar activity and selectivity toward C H production, showing the possibility for practical applications. Interestingly, this strategy can be applied to other various photocatalysts (Au-WO , Au-TiO , Au-CeO , Pd-WO , and Ag-WO ), showing a certain universality. It is expected that the proposed mechanism adds another layer to our understanding of CH -to-C H conversion.