Menghan Yu,Nan Wang,Kuo Lin,Dongxue Song,Jie Chen,Teng Liang,Jianhui Sun,Kai Pan,Honggang Fu
Photocatalytic selective oxidation of benzyl alcohol into benzaldehyde at normal temperature and pressure is one of the important topics in the catalysis field. Here, a lead-free double perovskite Cs2AgBiBr6 nanocrystal/mesoporous black TiO2 composite was prepared by a vacuum-assisted method, and then it was applied for photocatalytic selective oxidation. The photocatalytic oxidation of benzyl alcohol to benzaldehyde was found to occur with 75% conversion and 99% selectivity with the Cs2AgBiBr6 nanocrystal/black TiO2 composite, which were better than those of single Cs2AgBiBr6 nanocrystals and black TiO2, respectively. This was due to the formation of a Z-type heterogeneous structure between Cs2AgBiBr6 nanocrystals and black TiO2, which effectively promoted the separation and transfer of electrons and holes, ultimately leading to excellent photocatalytic activity. During the whole catalytic process, carbon-centered radicals were the key intermediates for the dehydrogenation of benzyl alcohol. This work may provide some practical suggestions for the fabrication of benzyl alcohol selective oxidation photocatalysts.
Liping Ren,Wei Zhou,Bojing Sun,Haoze Li,Panzhe Qiao,Yachao Xu,Jiaxing Wu,Kuo Lin,Honggang Fu
Defect-engineered magnetic γ-Fe 2 O 3 ultrathin nanosheets/mesoporous black TiO 2 hollow sphere heterojunctions (γ-Fe 2 O 3 /b-TiO 2 ) are fabricated by a metal-ion intervened hydrothermal technique and high-temperature hydrogenation, which exhibit wide-spectrum response and magnetic separation. The specific surface area, pore size and pore volume of the resultant γ-Fe 2 O 3 /b-TiO 2 with hollow structure are ∼63 m 2 g −1 , 10.5 nm and 0.14 cm 3 g −1 , respectively. After surface hydrogenation, α-Fe 2 O 3 nanosheets are converted to γ-Fe 2 O 3 ultrathin nanosheets (∼6 nm) combined with the formation of surface defects. The ultrathin nanosheet structure facilitates the surface engineering and also favors the diffusion and transportation of photogenerated charge carriers. The apparent rate constant (k) of defect-engineered γ-Fe 2 O 3 /b-TiO 2 photocatalytic degradation biotoxic tetracycline is ∼3 times higher than that of α-Fe 2 O 3 /b-TiO 2 under AM 1.5 irradiation. The enhancement is attributed to the introduction of narrow bandgap unit-cell-thick γ-Fe 2 O 3 nanosheets, the hollow structure and the defect engineering, which are beneficial to solar-light-harvesting and rapid electron transport, and spatial separation of photogenerated charge carriers. The photocatalytic degradation mechanism is also proposed. The novel magnetic γ-Fe 2 O 3 /b-TiO 2 heterojunction is a promising photocatalyst for recovering the domestic sewage in environment.
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