Efficient Photocatalytic CH4‐to‐Ethanol Conversion by Limiting Interfacial Hydroxyl Radicals Using Gold Nanoparticles

Abstract Photocatalytic CH 4 oxidation to ethanol with high selectivity is attractive but substantially challenging. The activation of inert C−H bonds at ambient conditions requires highly reactive oxygen species like hydroxyl radicals (⋅OH), while the presence of those oxidative species also facilitates fast formation of C 1 products, instead of the kinetically sluggish C−C coupling to produce ethanol. Herein, we developed a BiVO 4 photocatalyst with surface functionalization of Au nanoparticles (BiVO 4 @Au), which not only enables photogeneration of ⋅OH to activate CH 4 into ⋅CH 3 , but also in situ consumes those ⋅OH species to retard their further attack on ⋅CH 3 , resulting in an enhanced ⋅CH 3 /⋅OH ratio and facilitating C−C coupling toward ethanol. The ⋅CH 3 /⋅OH ratio is further improved by transporting CH 4 via a gas‐diffusion layer to the photocatalytic interface, leading to even higher ethanol selectivity and production rates. At ambient conditions and without photosensitizers or sacrificial agents, the BiVO 4 @Au photocatalyst exhibited an outstanding CH 4 ‐to‐ethanol conversion performance, including a peak ethanol yield of 680 μmol ⋅ g −1 ⋅ h −1 , a high selectivity of 86 %, and a stable photoconversion of >100 h, substantially exceeding most of the previous reports. Our work suggests an attractive approach of in situ generation and modulation of the ⋅OH levels for photocatalytic CH 4 conversion toward multi‐carbon products.