Highly efficient and accelerated photoreduction of nitrobenzene over visible-light-driven PtO@Cr2O3 nanocomposites

Abstract

PtO nanoparticles (NPs) were anchored mesoporous Cr2O3 networks through a surfactant-modified approach to synthesize PtO@Cr2O3 nanocomposites at varying PtO NPs contents, and the synthesized materials were evaluated by the reduction of nitrobenzene under visible light illumination. TEM images revealed PtO NPs (5 nm) with good distribution on the mesoporous Cr2O3 with a diameter of ∼20–30 nm. The obtained PtO@Cr2O3 nanocomposites exhibited highly Cr2O3 nanocrystallites with rhombohedral Cr2O3 structure and a large surface area of 85–110 m2/g. PtO@Cr2O3 nanocomposites revealed visible light absorption with red-shifted during the introduction of Cr2O3 NPs. The conversion efficiency of nitrobenzene increased up to 38%, 78% and 100% for 0.3, 0.6, 0.9 and 1.2%PtO@Cr2O3 photocatalysts within 60 min of illumination, which elucidating a nitrobenzene reduction effectively to yield aniline, where the conversion of nitrobenzene using bare Cr2O3 NPs was achieved only 6%. The obtained mesoporous 0.9%PtO@Cr2O3 nanocomposites exhibited the best photocatalytic reduction of nitrobenzene to aniline under visible light illumination with reduction rate of 3660.8 mmolL−1min−1 and reduction efficiency of 100% after 30 min. Interestingly, the reaction rate constant (k) and the photoreduction rate values over 0.9%PtO@Cr2O3 photocatalyst was fostered 47 and 22.5 folds larger than the obtained for bare Cr2O3. The significant improvement of mesoporous PtO@Cr2O3 nanocomposites could be attributed to the Cr2O3 modified by PtO sensitization, the mesoporous structure of Cr2O3 NPs and the synergic effects of PtO and Cr2O3. The recycling experiments of nitrobenzene photoreduction after five cycles runs were reduced slightly, which verified these candidates are considered a promising and superior for practical applications.