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Keywords: grain boundary; N2 fixation; operando oxygen vacancies; photocatalysis; WO3 In article number 1902319, Xusheng Zheng, Shuquan Liang, Liangbing Wang, and co-workers report that grain boundaries (GBs) in nanoporous WO SB 3 sb induce many operando oxygen vacancies under light irradiation. Grain boundary, N2 fixation, operando oxygen vacancies, photocatalysis, WO3. [Extracted from the article]

Photocatalysts with oxygen vacancies (OVs) have exhibited exciting activity in N2 photofixation due to their superiority in capture and activation of N2. However, the surface OVs are easily oxidized by seizing the oxygen atoms from water or oxygen during the catalytic reaction. Here, it is reported that the grain boundaries (GBs) in nanoporous WO3 induce plenty of operando OVs under light irradiation to significantly boost catalytic activity toward N2 photofixation. Impressively, nanoporous WO3 with abundant GBs (WO3‐600) exhibit an ammonia production rate of 230 µmol gcat.−1 h−1 without any sacrificial agents at room temperature, 17 times higher than that for WO3 nanoparticles without GBs. Moreover, WO3‐600 also manifests remarkable stability by maintaining nearly ≈100% catalytic activity after ten successive reaction rounds. Further mechanistic studies reveal that both OVs and GBs regulate the band structures of WO3 nanocrystals, as well as favor the delivery of photogenerated electrons to adsorbed N2 by enhancing W–O covalency. More importantly, plenty of operando OVs induced by GBs generate during catalytic reaction, directly contributing to the excellent catalytic performance for WO3‐600. This work opens a novel avenue to developing efficient photocatalysts by construction of operando OVs. [ABSTRACT FROM AUTHOR]