Surface oxygen vacancies of TiO2–x enabled water transfer photocatalytic hydrogenation of nitrobenzene to aniline without use of co-catalyst

Abstract

Water transfer photocatalytic hydrogenation of nitrobenzene to aniline is an attractive and environmentally friendly process in chemical manufacturing. Herein, through an in-situ CO reduction pathway, the TiO2-based photocatalysts with surface and subsurface VOs are prepared for water transfer hydrogenation of nitrobenzene to aniline. The CO originated from incomplete combustion of residual organic compounds of the TiO2 precursor (tetrabutyl titanate), can react with the lattice oxygen of TiO2 and obtain rich surface and subsurface VOs TiO2-based photocatalysts without additional reduction reagent. The as-prepared TiO2 catalyst exhibits a desired band structure and rapid separation of photogenerated carriers. Besides, the TiO2 catalyst with surface and subsurface VOs can stabilize intermediates for water transfer hydrogenation. Thus, compared with heteroatom doping and poor-VOs TiO2, the TiO2 catalyst exhibits highly selectivity and conversion for photocatalytic hydrogenation of nitrobenzene substrates without the use of any cocatalyst and reductant H2.