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光催化被广泛用于去除水中的难降解有机污染物,但是由于光生电子和空穴的复合率高,抑制了半导体光催化剂的催化活性。本研究通过简便的溶剂热法成功制备了一种BiOBr/ZnMoO4复合材料。通过结构分析、原位XPS、功函数测试、自由基捕获及电子顺磁共振(ESR)实验等证实了BiOBr/ZnMoO4复合材料形成了S型异质结。实验结果表明,适当ZnMoO4含量的BiOBr/ZnMoO4异质结可以显著提高BiOBr的光催化性能。与纯BiOBr、ZnMoO4相比,质量分数15%BiOBr/ZnMoO4在可见光下表现出最佳的光催化活性,双酚A的光催化降解率达到85.3%(90min),环丙沙星的光降解速率常数分别是BiOBr的2.6倍和ZnMoO4的484倍。这可归因于BiOBr和ZnMoO4之间形成了紧密的界面结合和S型异质结,使得光生载流子可以实现有效的空间分离和转移。这项工作为定向合成Bi基S型异质结复合光催化材料提供了一种... 相似文献
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《无机盐工业》2015,47(6):74
室温沉淀法合成溴氧化铋(BiOBr)纳米片,然后通过离子交换法制备溴化银/溴氧化铋(AgBr/BiOBr)复合纳米材料,采用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)及紫外可见分光光度计(UV-Vis)对其进行表征,并进行了光催化降解实验。以节能、绿色的LED灯为可见光光源,AgBr/BiOBr复合材料光催化降解罗丹明B(RhB)和甲基橙(MO)的效率均高于BiOBr。AgBr/BiOBr降解RhB的活性强于MO。在AgBr/BiOBr光催化系统中,超氧自由基和空穴是主要的活性物种。不同pH条件下,AgBr/BiOBr对RhB均表现出理想的光催化降解效果,酸性条件下降解效率最佳;碱性环境下AgBr/BiOBr光催化降解MO的活性最高。经过循环利用,AgBr/BiOBr可见光催化活性呈现出一定程度的降低,归因于降解过程中产生了金属银。 相似文献
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采用水热法合成了Yb3+-Tm3+共掺BiOBr纳米晶, 研究了其上转换发光性能。在980 nm光激发下, 样品中Tm3+离子实现了3H4→3H6、1G4→3F4和1G4→3H6跃迁, 进而发出强烈的近红外光(801 nm)和较弱的红光(655 nm)与蓝光(485 nm)。探讨了样品的上转换发光机理, 上转换发光强度与激发功率的关系表明在980 nm激发下Tm3+的蓝光和红光发射为三光子过程, 而近红外发光为双光子过程。随着Yb3+浓度增加, 近红外发光显著增强, 近红外光与蓝光(I801 nm/I485 nm)的发光强度比高达71.4。研究结果表明, Yb3+-Tm3+共掺BiOBr纳米晶在生物荧光标记领域具有潜在的应用前景。 相似文献
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使用混合溶剂热法,以1-己基-3-甲基咪唑溴盐离子液体([Hmim]Br)和Bi(NO3)3·5H2O为反应物,乙二醇水溶液为溶剂,制备了BiOBr微球和纳米片。利用X射线衍射(XRD)、扫描电镜(SEM)、紫外可见漫反射(UV-Vis)以及N2吸附-脱附等手段对其进行了物相和结构的表征。在可见光照射下,以罗丹明B(RhB)为目标污染物,研究了离子液体存在下,溶剂组成对BiOBr光催化活性的影响。结果表明,当乙二醇与水的比例为3∶1~1∶1时所制备的BiOBr纳米片具有最高的光催化活性;同时,BiOBr纳米片光催化剂稳定性良好,循环使用8次后光催化活性基本稳定。 相似文献
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《Ceramics International》2016,42(15):16463-16468
BiOBr-reduced graphene oxide (RGO) composites were successfully synthesized via a simple hydrothermal method. Their morphology, structure and photocatalytic activity in the degradation of nitrobenzene were characterized by scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption, UV–vis absorption spectroscopy, photoluminescence spectra, electrochemical impedance spectra and total organic carbon, respectively. The results showed that the introduction of RGO could enhance the visible light photocatalytic activity of BiOBr. The BiOBr-RGO composite with 0.6 wt% RGO exhibited an optimal photocatalytic activity, and the maximum degradation rate of nitrobenzene was about 2.16 times that of pure BiOBr due to the increased light absorption and the reduced electron-hole pair recombination in BiOBr with the introduction of RGO. 相似文献
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《Advanced Powder Technology》2020,31(8):3618-3627
Bismuth oxybromide (BiOBr) was synthesized in aqueous medium in presence of EDTA as structure-directing agent following a simple coprecipitation method at 23 °C and by microwave irradiation at 110 °C. The physicochemical properties of BiOBr (morphology, specific surface area, energy band gap and photocatalytic activity) were modified using different EDTA concentrations. Nanoparticles of BiOBr with {1 1 0} crystallographic exposed facets were obtained as a peculiar feature of the synthesis followed. The photocatalytic activity of BiOBr was evaluated in the oxidation reaction of nitric oxide (NO) in gaseous phase under UV–Vis and visible irradiation. An enhancement in the NO conversion degree was reached for BiOBr synthesized by coprecipitation with an EDTA/Bi molar ratio of 0.6. This sample showed a NO conversion degree of 94%, a selectivity to nitrate ions of 98%, a good stability after four cycles of irradiation and sample was able to retain its high photocatalytic activity under humidity conditions (70% RH). The use of different chemical scavengers revealed that superoxide radical (O2•-) was the main reactive specie in the mechanism of the photocatalytic reaction. BiOBr photocatalyst was successfully incorporated in two formulations of ceramic coatings to develop prototypes of building materials with active surface for the photocatalytic elimination of NOx gases from the air. 相似文献
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Using solar energy through green and simple artificial photosynthesis systems are considered as a promising way to solve the energy and environmental crisis. However, one of the important primary steps of photosynthesis, i.e., energy transfer, is long being ignored especially in inorganic semiconducting systems due to the small exciton binding energies. Herein, the simultaneous interrogation of the charge transfer and energy transfer steps in a photoexcitation process is proposed by utilizing few-layered nanosheet-assembled hierarchical BiOBr nanotubes with rich oxygen vacancies (OVs) as efficient multifunctional photocatalysts. Benefiting from the integrated 1D/2D structure and abundant OV defects, the excitonic effect strikes a delicate balance in the optimized BiOBr photocatalyst, showing not only improved charge carrier separation and transfer but also enhanced exciton generation. As a result, the hierarchical BiOBr nanotubes exhibit high efficiency toward photocatalytic CO2 reduction with an impressive CO evolution rate of 135.6 µmol g−1 h−1 without cocatalyst or photosensitizer. The dominant reactive oxygen species of singlet oxygen (1O2) are discriminated for the first time, which originated from an energy transfer process, with electrophilic character, whereas the minor effect of superoxide anion radical (•O2−) with a nucleophilic rate-determining step in the photocatalytic aerobic oxidation of sulfides. 相似文献