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

Abstract

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.