Highly Selective Photo-Oxidation of Methane to Methanol by Fe–Au Site-Supported SrTiO<sub>3</sub> Hollow Nanotubes with Oxygen Vacancies
Yangyang Zhu, Zhuo Li, Ji Bian, Ziqing Zhang, Cailing Chen, Lunqiao Xiong, Junwang Tang, Liqiang Jing
Abstract
Solar-driven methane (CH 4 ) conversion to value-added chemicals with high selectivity remains a long-standing challenge. Here, we present closely attached atomically dispersed Fe species and ultrafine Au-supported SrTiO 3 hollow nanotubes with oxygen vacancies (STO v ) for highly selective CH 4 conversion to CH 3 OH. An impressive CH 3 OH production rate of 7.53 mmol g –1 h –1 with a selectivity up to 95.4% has been achieved, corresponding to an apparent quantum efficiency of 15.8% at 365 nm, representing a record among all of the representative photocatalysts under comparable conditions. Experimental results and theoretical simulations elucidate that the created oxygen vacancies on SrTiO 3 without Ti 3+ facilitate CH 4 adsorption to effectively capture photogenerated holes for producing methyl radicals. In parallel, the photogenerated electrons could be rapidly extracted by the anchored Au and then transferred to the adjacent single-atom Fe sites for activating O 2 to generate the key intermediate Fe–*OOH toward highly selective CH 3 OH production. Significantly, a commendable electron transfer efficiency of 67.5% for O 2 activation is achieved on Fe–Au/STO v based on the quantitative in situ microsecond transient absorption spectra. This work provides a deep understanding of the regulation of both activity and selectivity by the engineering of adjacent sites and the investigation of electron kinetics for O 2 activation during CH 4 photo-oxidation.