As underlined in the COP26, methane as a greenhouse gas is nearly 80 time more potent than CO2 while its reserve is much more than the sum of coal, oil and natural gas. Thus methane conversion not only involves the environmental issue but also is related to high-value chemical production /clean energy supply, which has been attracting substantial interest over the last decades. However CH₄ activation is energy intensive and kinetically very challenging so that methane activation is regarded as the “holy grail” in the catalytically chemical process. [1] Photocatalysis provides a cost efficient potential to activation of such small molecule under very mild conditions, while to achieve the potential is a huge challenge.[2]

Stimulated by our research outcomes on the charge dynamics in inorganic semiconductor photocatalysis, which reveal that the low reaction efficiency is due to both fast charge recombination and large bandgap of an inorganic semiconductor [3,4], together with the recent findings on atomic catalysis [5], we developed novel material strategies for photocatalytic methane conversion to methanol.

Highly dispersed atomic level iron species immobilised on a TiO₂ photocatalyst show an excellent activity for methane conversion, resulting into ~97% selectivity towards alcohols operated under ambient conditions by a one-step chemical process [6]. Such photocatalyst is also very stable, promising an attractive industrial process of methane upgrade. The dominating function of the iron species has also been investigated in detail. Furthermore, we designed a flow system for relatively efficient methane to C2, achieving the benchmark results in this area.[7] In addition, C1 oxygenates can be produced with nearly 100% by photocatalytic methane conversion due to the synergy between Au and Cu cocatalysts loaded on ZnO.[8]

References：

1. Li, X. Wang, C., Tang, J. Nature Reviews Materials, 2022, Doi: 1038/s41578-022-00422-3.
2. Wang Y., Suzuki H., Xie, J., Tomita, O., Martin, D. J., Higashi, M., Kong, D., Abe R. Tang, J., Chem. Rev., 2018, 118: 5201-5241.
3. Tang, J. Durrant J. R., Klug, R ., J. Am. Chem. Soc., 2008, 130(42) : 13885-13891.
4. Miao, T., Wang, C., Xiong, L., Li, X., Xie, X., Tang, J., ACS Catalysis, 2021, 11, 8226-8238.
5. Wang, A. Li J., Zhang. T., Nat. Rev. Chem., 2018, 2; 65-81.
6. Xie, J., Jin, R. ,Li, A., Bi, Y., Sankar, G. , Ma , Tang, J. Nature Catalysis, 2018, 1: 889-896.
7. Li, X., Xie J.,Rao, H., Wang, , Tang, J., Angewandte Chemie International Edition, 2020, 132: 19870-19875.
8. Luo, L., Gong, Z., Xu, Y., Ma, J., Liu, H., Xing, J., Tang, J., Journal of the American Chemical Society, 2022, 144, 2, 740–750.