Highly Selective Photo-Oxidation of Methane to Methanol by Fe-Au Site-Supported SrTiO3 Hollow Nanotubes with Oxygen Vacancies.

Solar-driven methane (CH4) 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 SrTiO3 hollow nanotubes with oxygen vacancies (STOv) for highly selective CH4 conversion to CH3OH. An impressive CH3OH 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 SrTiO3 without Ti3+ facilitate CH4 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 O2 to generate the key intermediate Fe-*OOH toward highly selective CH3OH production. Significantly, a commendable electron transfer efficiency of 67.5% for O2 activation is achieved on Fe-Au/STOv 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 O2 activation during CH4 photo-oxidation.