Mesoporous ZnCr2O4 photocatalyst with highly distributed PtO nanoparticles for visible-light-induced photoreduction of nitrobenzene

Achieving uniformly stable and dispersed PtO NPs on mesoporous ZnCr 2 O 4 is considered a challenge in heterogeneous photocatalysis. Herein, spinel mesoporous ZnCr 2 O 4 NPs were constructed by the sol-gel approach in the occurrence of nonionic surfactant as a structure-directing agent. Highly dispersed PtO NPs (∼3–5 nm) could be obtained at different percentages (0.3–1.2%) by a simple impregnation-calcination approach, resulting in strong interactions between PtO and ZnCr 2 O 4 NPs. The PtO@ZnCr 2 O 4 photocatalyst resulted in remarkable enhancement in the photoreduction of nitrobenzene to yield aniline under visible light exposure, which manifested the highest photoreduction ability, about 32%, 72%, 100% and 100% for 0.3, 0.6, 0.9 and 1.2%PtO@ ZnCr 2 O 4 photocatalysts, respectively within 60 min. The photoreduction rate of 0.9%PtO@ZnCr 2 O 4 photocatalyst is faster 23 times than bare ZnCr 2 O 4 NPs. The 0.9%PtO@ZnCr 2 O 4 photocatalyst indicated a much higher photoreduction ability, and its rate constant value was enhanced 38 folds larger than the bare ZnCr 2 O 4 NPs. The enhancement of PtO@ZnCr 2 O 4 photocatalyst was attributed to superior optical absorption capability over the well-contacted PtO/ZnCr 2 O 4 heterojunction and boosting the ability of charge separation. PtO@ZnCr 2 O 4 photocatalyst exhibited high stability and did not indicate any sign of deactivation after five times recycle. • Mesoporous PtO@ZnCr 2 O 4 was synthesized by a simple sol-gel route with template. • The photoreduction ability over 0.9% PtO@ZnCr 2 O 4 photocatalyst was ∼100%. • Photoreduction rate of PtO@ZnCr 2 O 4 is faster 23 times than bare ZnCr 2 O 4 NPs . • The rate constant of PtO@ZnCr 2 O 4 is enhanced 38 folds larger than ZnCr 2 O 4 NPs. • PtO@ZnCr 2 O 4 photocatalyst exhibited high stability and durability for five cycles.