Length Lewis acid Fe3+ in TiO2 ultra-thin nanosheet boosts oxygen species activation

Breaking the bottleneck of the light absorption, photocarriers transmission and separation (PTS), and surface reactions efficiency of photocatalysis is hot topic. For this, the Fe3+ acted as Lewis acid site is successfully built in TiO2 ultra-thin nanosheet (FT) through hydrothermal method. The detailed effect of Lewis acid site is systematically studied. Based on DFT, in-situ XPS, O-2 TPD, CV, hole transfer efficiency (eta trans) and ESR, Lewis acid of Fe3+ acts as a photo-generated electron trapped site, and the imbalance of charge by the construction of Lewis acid, which makes the O-2 reduction process more easily occurs on Ti-4(+) (adjacent to the Lewis acid site) as well as Lewis acid site itself. Meanwhile, the oxygen defect (OD) near Lewis acid site promotes the adsorption, activation and oxidation of H2O. The photo-redox reaction is simultaneously accomplished around the Lewis acid site, which is the PTS driving force of photocarriers. The photocurrent density of 5% FT is 4 to 5 times higher than intrinsic one (T), and Lewis acid site of Fe3+ leads to the reduction of interfacial resistance due to lower the activation energy of redox process. As result, FT displays higher photocatalytic activity than T.

Automated summary

Introducing Fe3+ Lewis acid sites into TiO2 ultra-thin nanosheets can significantly enhance the photocatalytic activity. The Lewis acid sites trap photo-generated electrons and promote the O-2 reduction process through charge imbalance. Additionally, oxygen defects near Lewis acid sites facilitate the adsorption, activation, and oxidation of water molecules. The photo-redox reaction occurs simultaneously around the Lewis acid sites, driving the photocarriers' transmission and separation.