Tuning the reactivity of TiO2 layer with uniform distribution of Sub-5 nm Fe2O3 particles via in situ voltage-assisted oxidation for robust catalytic reduction

The trade-off between efficiency and stability has limited the application of TiO2 as a catalyst due to its poor surface reactivity. Here, we present a modification of a TiO2 layer with highly stable Sub-5 nm Fe2O3 nanoparticles (NP) by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation approach. In situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe2O3 NP embedded within porous TiO2 layer. Comprehensive surface characterizations with density functional theory demonstrated an improved electronic transition in TiO2 due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe; it also unexpectedly increased the active site in the TiO2 layer due to uncoordinated electrons in Sub-5 nm Fe2O3 NP/TiO2 catalyst, thereby enhancing the adsorption of chemical functional groups on the catalyst. This unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol, achieving approximately 99% efficiency in 20 ​min without stability decay after 20 consecutive cycles, outperforming previously reported TiO2-based catalysts. This finding proposes a modified-electrochemical strategy enabling facile construction of TiO2 with nanoscale oxides extandable to other metal oxide systems.