Axially wrinkled SnO 2 /TiO 2 heteronanotubes have been successfully prepared by sacrificial template method combined with hydrothermal synthesis. The special folded morphology of SnO 2 /TiO 2 nanostructures may provide more active sites, and the S-scheme heterojunction between SnO 2 and TiO 2 enhances the separation of photogenerated electron-hole pairs, which are conducive to the improvement of photocatalytic degradation for organic pollutants. Using SnO 2 /TiO 2 nanotubes as catalyst, the removal rate of Rhodamine B (RhB), methyl orange (MO) and tetracycline hydrochloride (TCH) under the irradiation of a xenon lamp is 93%, 91% and 85%, respectively. After five cycles, the removal efficiency of organic pollutants maintains almost unchanged, indicating that the synthesized SnO 2 /TiO 2 nanotubes has good stability and reusability. In addition, trapping experiments have been carried out to investigate the major reactive oxidative species for organic pollutants photodegradation. This study provides a facile avenue to design nanotublar photocatalysts with enhanced degradation performance for organic pollutants.
Amorphous SnO 2 was coupled on the surface of mixed-phase TiO 2 nanoflowers (NFs) by a solvothermal synthesis. Various characteristics confirms the formation of SnO 2 /TiO 2 heterostructures. As-prepared amorphous SnO 2 /TiO 2 heterostructures revealed uniform morphology and enhanced photoelectrochemical performance. Underfull-spectrum light irradiation, the SnO 2 /TiO 2 heterostructures with an optimized SnO 2 ratio revealed the best photoreduction performance, in which Cr(VI) of 99% was removed within 30 min. This is ascribed to the introduction of amorphous SnO 2 , which adjusted the band gap structure, increased specific surface area of TiO 2 NFs, and greatly enhanced the photoelectric conversion efficiency. The mechanism of the heterostructure formation and enhanced photoreduction for Cr(VI) ions were discussed. The TiO 2 NFs with a mixture phase helps to improve the separation efficiency of photogenerated carriers. This result provides an unique idea for the construction of heterostructures.
Weining Liu,Xi Tan,Mingyang Zhao,Zhao Liu,Hairong Li
Triethylamine (TEA) is a highly toxic and flammable volatile organic compound (VOC) that poses serious risks to both human health and environmental safety. Thus, the development of highly sensitive gas sensors for its trace-level detection is of pressing importance. In this work, SnO 2 /TiO 2 heterostructures were synthesized via an in-situ thermal transformation of Sn-MOF/MXene precursors. The derived materials benefit from the inherent high porosity and large specific surface area of MOF-based frameworks, as well as the tightly coupled heterointerface formed under the modulation of MXene, efficiently facilitating charge separation and transport, while TEA interacts more readily with active sites due to the richness of surface defects, thereby greatly boosting TEA adsorption and sensing response. The optimized MST-2 sensor exhibits an ultrahigh response of 3525.2 to 10 ppm TEA at a notably low operating temperature of 61 °C, along with excellent selectivity and good stability. Even at an ultralow TEA concentration of 10 ppb, the sensor maintains a strong response of 44.6. Furthermore, the adsorption characteristics of individual phases, interfacial charge transfer processes, and TEA adsorption enhanced mechanisms were systematically examined through density functional theory (DFT) calculations. The effective MOF/MXene-derived co-construction strategy offers a promising avenue for designing advanced TEA sensing materials.
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