Photoinduced in Situ Deposition of Uniform and Well-Dispersed PtO<sub>2</sub> Nanoparticles on ZnO Nanorods for Efficient Catalytic Reduction of 4‑Nitrophenol

Based on the photochemical property of semiconductors, a light irradiation-assisted strategy has been designed using one-dimensional ZnO nanorods as carriers to synthesize the rod-type PtO<sub>2</sub>/ZnO catalyst with a well-defined structure. The high crystallinity and uniform crystal structure of the ZnO matrix conduct the in situ deposition of PtO<sub>2</sub> nanoparticles with 1.1–2.1 nm, which are evenly and densely anchored on the surface. Those small-sized and well-dispersed PtO<sub>2</sub> nanoparticles endow the PtO<sub>2</sub>/ZnO catalyst a superior catalytic performance for the reduction of 4-nitrophenol to 4-aminophenol, which can convert all the substrates within 6.25 min. It is demonstrated that the catalytic activity of the PtO<sub>2</sub>/ZnO catalyst is 2.3 times as high as that of the sample obtained by traditional wet-oxidation method under the same reaction conditions. Moreover, the light-irradiation time has been found to greatly affect the structure and activity of PtO<sub>2</sub>/ZnO catalysts, and the product with 30 min exhibits the best catalytic performance in this work, as well as the good stability for ten runs. In terms of the photoexcited process of ZnO and reactive species-trapped experiments, the formation mechanism of PtO<sub>2</sub>/ZnO catalysts has been explored in detail, which will probably stimulate the design and study of other metal-supported catalysts.