Photocatalytic selective oxidation of alcohols into corresponding aldehydes has received enormous attention. However, it remains a great challenge to explore photocatalysts with high conversion efficiency and selectivity. Herein, we developed a composite consisted of TiO 2 and Ti 3 C 2 through a simple calcination of Ti 3 C 2 nanosheets. It was found that Ti 3 C 2 could stabilize the oxygen vacancies and Ti 3+ species in the TiO 2 /Ti 3 C 2 composite, which could subsequent promote the production of active intermediates during the photocatalytic oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). Additionally, the valence band of TiO 2 in the composites was found to be up-shifted, which would avoid the further oxidation of BAD and enhance selectivity. As a result, the optimal composite exhibits the BA conversion efficiency of 97 % and BAD selectivity of 98 %, which is 2.8 and 1.2 folds higher than that of pristine TiO 2 . Our work may provide insights for designing efficient photocatalysts for selective oxidation of alcohols.
Xiaoyun Ye,Hangyu Zhong,Long Chen,Yumei Zhang,Yuping Wu,Wei Tian,Li-An Ma,Qianting Wang
Reasonable interface design is a key factor to improve the activity of photocatalysts. In this paper, TiO 2 /Ti 3 C 2 composite photocatalyst with high activity of anatase/rutile mixed crystal were prepared by solid-phase milling-roasting method. The microstructure of the mixed-phase TiO 2 /Ti 3 C 2 composites could be adjusted by the calcination temperature and additive content. The results showed that NaBF 4 could promote the transformation of anatase TiO 2 to rutile TiO 2 . An appropriate amount of rutile TiO 2 forms a heterojunction with anatase TiO 2 , which enables efficient charge separation and transfer at the interfaces of the composites. The optimized sample (MT550) showed 98 % degradation of rhodamine B (RhB) under visible light irradiation within 180 min, which was 8 times higher than that of the sample without added NaBF 4 . This study presents a strategy for the synthesis of mixed-phase (anatase/rutile) TiO 2 /Ti 3 C 2 composites with high activity under visible light, which has potential in the design and application of photocatalytic materials.
Photocatalytic removal of tetracycline (TC) from wastewater is an advantageous method with green and efficient potentials, while the low light utilization and severe charge carrier recombination of conventional photocatalysts limit their practical application. The TiO 2 /Ti 3 C 2 derived from in-situ partly oxidation of Ti 3 C 2 MXene precursors on which Bi 2 MoO 6 (BMO) was tightly loaded was synthesized via a facile hydrothermal synthesis route. The introducing TiO 2 /Ti 3 C 2 accelerated the transfer of electrons, improving the efficiency of electron-hole separation, thus strengthened the photocatalytic performance. Under optimum conditions, the BMO/TiO 2 /Ti 3 C 2 composite significantly removed 87.54 % TC from wastewater within 150 min, which was higher than the original counterparts and remained almost unchanged after four cycles. The active species trapping experiments and ESR analysis displayed that •O 2 - played a dominant role in TC degradation. The possible degradation pathways were also deduced through liquid chromatography-mass spectrometry (LC-MS) analysis experiments, demonstrating that the terminal products of degradation were mainly CO 2 and H 2 O, confirming the potential of BMO/TiO 2 /Ti 3 C 2 photocatalyst for the environmentally friendly treatment of antibiotic pollutants in wastewater.
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