Synthesis of Pt-loaded self-interspersed anatase TiO₂ with a large fraction of (001) facets for efficient photocatalytic nitrobenzene degradation

TiO₂ is capable of directly utilizing solar energy for sustainable energy harvest and water purification. Facet-dependent performance of TiO₂ has attracted enormous interests due to its tunable photocatalytic activity toward photoredox transformations, but information about the noble-metal-loaded TiO₂ for its facet-dependent photocatalytic performance, especially in pollutant degradation systems, is limited. In this work, inspired by our previous theoretical calculations about the roles of the crystal surface in Pt-loaded TiO₂ in its enhanced photocatalytic capacity, TiO₂ nanocrystals with interspersed polyhedron nanostructures and coexposed (001) and (101) surfaces as a support of Pt nanoparticles are prepared in a simple and relatively green route. Also, their performance for photocatalytic degradation of nitrobenzene (NB), a model organic pollutant, is explored. The experimental results demonstrate that the NB photodegradation and photoconversion efficiencies are significantly enhanced by uniformly loading Pt nanoparticles on the crystal surfaces, but the Pt nanoparticles deposited on only the (101) surface have no contribution to the improved NB photodegradation. Furthermore, the liquid chromatography mass spectrometry results also show that NB photodegradation tends to proceed on the (001) surface of Pt/TiO₂ for the generation of nitrophenol intermediates through the photooxidation pathway. This work provides a new route to design and construct advanced photocatalysts toward pollutant photoredox conversions and deepens our fundamental understanding about crystal surface engineering.