Yuqing Chen,Chun Shen,Jie Wang,Gang Xiao,Guangsheng Luo
As the energy shortage and environmental problem become the worldwide concern, the green synthesis of catalysts and their green applications have long been pursued. Here we proposed a facile catalyst synthesis approach in which Ag–TiO2 composites were prepared through an in situ reduction at room temperature without severe conditions or hydrogen atmosphere. Porous glass (PG) was chosen as the support, and the as-prepared Ag–TiO2/PG was equipped with the remarkable merits of intense visible light absorbance, effective separation of electron–hole pairs, high surface areas for adsorption, and abundant reactive sites for the photocatalytic oxidation. Conversions of 95.2% and 92.1% for dibenzothiophene (DBT) and benzothiophene (BT), respectively, were realized under irradiation of energy-saving visible light emitting diodes (LEDs), complying with the principles of “green chemistry”. Moreover, none of the external oxidants, such as H2O2 or O2, was introduced, greatly increasing the viability of industrial applications. Ag–TiO2/PG also showed remarkable activity for removing rhodamine B (RhB), methylene blue (MB), and methylene orange (MO) with the rate constants of 0.14, 0.18, and 0.055 min–1, respectively. The mechanism study revealed that the immobilized Ag acted as the role of “killing two birds with one stone”: enhancing the absorption of visible light, suppressing the recombination of photoinduced electron–hole pairs via trapping electrons, and contributing to the generation of •O2–. In addition, oxygen vacancies, •OH, and h+ also took part in the photocatalytic oxidation. This work explored the green synthesis of Ag–TiO2/PG and characterized their excellent photocatalytic activity for photocatalytic desulfurization and degradation of organic dyes, opening up new possibilities for low-energy-consumption photocatalysis and sustainable chemistry.
In this work, Ag/TiO 2 composite was prepared by photo-reduction method. The study of photocatalytic degradation of different organic pollutants found that microwave can enhance the photocatalytic degradation rate . Further studies have shown that photo-generated holes are the main active species involved in photocatalytic degradation. Under microwave irradiation , silver nanoparticles can not only promote the charge separation process, but also enhance the adsorption of organic pollutants on the surface of TiO 2 .
Congyu Wang,Zepeng Rao,Asad Mahmood,Xiao Wang,Yan Wang,Xiaofeng Xie,Jing Sun
In the process of photocatalytic oxidation (PCO), titanium dioxide (TiO 2 ) shows excellent capabilities. However, when TiO 2 is used to remove volatile organic compounds (VOCs), there are some drawbacks including weak adsorption of gaseous contaminants, insufficient utilization of sunlight, and rapid recombination of photogenerated carriers. Herein, a TiO 2 -based ternary heterogeneous photocatalyst, g-C 3 N 4 /Ag-TiO 2 , was successfully fabricated to photodegrade gaseous acetaldehyde (one of the representatives of oxygenated VOCs) under visible light. Among the various samples, the g-C 3 N 4 /50 wt% Ag-TiO 2 exhibited an excellent photocatalytic activity , which was 5.8 times of bare TiO 2 . The mineralization efficiency of acetaldehyde was also increased by 3.7 times compared to bare TiO 2 . The substantial improvement in the PCO performance of the ternary system can be associated with the good adsorption to acetaldehyde gas and light-harvesting capability, as well as improved charge separation process. The application of Langmuir-Hinshelwood kinetic model suggested that relative humidity played a significant role in the VOCs degradation. Also, the photodegradation of gaseous acetaldehyde primarily occurred on the catalysts surface. Based on several characterizations, i.e., UV–vis spectroscopy, photoluminescence spectrum, photocurrent spectroscopy and electron spin-resonance test, a suitable degradation mechanism is proposed. This study provides a novel ternary photocatalyst with improved photocatalytic performance and stability, which can be used for the low-concentration VOCs abatement in the indoor environment.
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