高效碳量子点/BiOCl纳米复合材料用于光催化污染物降解（英文）

为了克服单纯BiOCl光谱吸收范围窄和载流子复合几率高的缺点,本研究制备了一种具有高效光催化活性的碳量子点(CQDs)/BiOCl纳米复合材料。光催化降解罗丹明B染料实验表明CQDs/BiOCl纳米复合材料的光催化性能远优于单纯的BiOCl,其光催化性能约为后者的3.4倍。当CQDs的复合量为7.1wt%时,样品的光催化性能最佳,能够在2 min之内将罗丹明B完全脱色,而单纯的BiOCl在相同时间内对罗丹明B的降解率仅为29.5%。通过紫外-可见漫反射谱、光电化学测试以及自由基捕获实验揭示了CQDs/BiOCl纳米复合材料的光催化性能提升机理,结果表明CQDs可以拓展BiOCl的可见光吸收范围,这有利于增强其光捕获能力以及促进电子–空穴对的产生。除此之外, CQDs独特的上转换发光行为,以及光诱导的电子转移能力提升了CQDs/BiOCl纳米复合材料光催化性能。     

BiOCl/CQDs复合催化剂的制备及光催化性能研究

以葡萄糖为碳源,水热法合成水溶性碳量子点(CQDs),通过超声辅助水解法将其与氯氧化铋(BiOCl)复合,制备BiOCl/CQDs复合光催化剂。采用傅里叶红外光谱、X射线衍射、扫描电子显微镜和荧光分光光度计对BiOCl/CQDs的结构与性能进行了表征。并以罗丹明B为降解底物,考察不同碳点含量的复合光催化剂的光催化性能。结果表明,和纯相氯氧化铋相比,复合光催化剂的降解率有所提高。碳点浓度为1.5mg/mL,降解时间为40min时,罗丹明B的降解率可达到93%。     

g-C3N4/BiOCl复合光催化剂作为2D/2D异质结用于光催化降解染料性能研究

为扩大BiOCl的太阳光吸收范围,获得更高效的光催化剂,本文通过水热法制备了石墨相氮化碳(g-C₃N₄)/BiOCl (2D/2D)复合光催化剂并对其进行详细表征。结构与形貌表征结果显示BiOCl纳米片沉积在层状g-C₃N₄表面,形成了2D/2D面-面复合结构;光电化学性质分析表明形成的异质结构能有效扩展光吸收频率范围,促进光生载流子分离和迁移,从而有利于光催化性能的提高。以500 W氙灯模拟太阳光源,光催化降解罗丹明B(RhB)的结果表明g-C₃N₄/BiOCl异质结的光催化降解活性远高于单纯的g-C₃N₄和BiOCl。其中9wt%g-C₃N₄/BiOCl表现出了最优越的光催化活性,在180 min内对RhB的降解率为94%,其表观速率常数K_app值为g-C₃N₄和BiOCl的5.7和3.6倍。同时对g-C₃N₄/BiOCl异质结的光催化机制展开研究,结合复合催化剂电子结构和自由基捕获实验提出了在染料敏化作用下RhB的光催化降解机制。      

碳量子点/BiPO_4纳米复合材料增强的可见光吸收和电荷分离

通过水热法一步合成了具有增强可见光吸收和电荷分离的碳量子点/BiPO_4纳米复合光催化材料。通过降解罗丹明B染料表征了碳量子点/BiPO_4纳米复合材料的光催化性能。结果表明:在模拟太阳光或可见光的照射下,碳量子点/BiPO_4复合材料的光催化性能均优于单纯的BiPO_4。碳量子点/BiPO_4复合材料光催化性能的提升可归因于碳量子点对可见光的吸收增加了太阳光的利用率,以及碳量子点的电子转移和储存性质提高了材料的电荷分离效率。     

增强可见光吸收和电荷分离的碳量子点/BiPO_4纳米复合材料（英文）

通过水热法一步合成了具有增强可见光吸收和电荷分离的碳量子点/BiPO_4纳米复合光催化材料。通过降解罗丹明B染料表征了碳量子点/BiPO_4纳米复合材料的光催化性能。结果表明:在模拟太阳光或可见光的照射下,碳量子点/BiPO_4复合材料的光催化性能均优于单纯的BiPO_4。碳量子点/BiPO_4复合材料光催化性能的提升可归因于碳量子点对可见光的吸收增加了太阳光的利用率,以及碳量子点的电子转移和储存性质提高了材料的电荷分离效率。     

增强可见光吸收和电荷分离的碳量子点/BiPO4纳米复合材料

通过水热法一步合成了具有增强可见光吸收和电荷分离的碳量子点/BiPO₄纳米复合光催化材料。通过降解罗丹明B染料表征了碳量子点/BiPO₄纳米复合材料的光催化性能。结果表明：在模拟太阳光或可见光的照射下,碳量子点/BiPO₄复合材料的光催化性能均优于单纯的BiPO₄。碳量子点/BiPO₄复合材料光催化性能的提升可归因于碳量子点对可见光的吸收增加了太阳光的利用率,以及碳量子点的电子转移和储存性质提高了材料的电荷分离效率。     

有序大孔-介孔Au-TiO_2复合材料的制备及其光催化性能

为提高TiO_2的光吸收和光催化能力,采用原位水热还原法将Au沉积到有序多孔TiO_2上,制备了有序大孔-介孔Au-TiO_2复合材料。材料的光催化活性以在紫外光和可见光辐射下降解罗丹明B来评价。漫反射吸收光谱显示Au-TiO_2复合材料在400~800nm有较强的吸收。在紫外光和可见光辐射下,Au-TiO_2复合材料的光催化活性优于TiO_2。在紫外光下Au-TiO_2-1.9是最高效的催化剂,3h内罗丹明B的降解率达84%,其表观速率常数K是TiO_2的2.8倍。这主要是因为沉积Au纳米粒子能有效促进电荷的分离,提高光催化效率,但过量的Au成为表面电子-空穴复合的中心,反而降低其光催化能力。在紫外光下,罗丹明B的降解反应属于准一级动力学反应,光生空穴是主要的活性物质。阻抗测试显示Au-TiO_2的圆弧半径小于TiO_2,表明电荷传递效率提高,有利于光生电子-空穴对的分离和光催化性能的提高。     

纳米TiO2/聚氯乙烯共轭衍生物复合材料的制备及可见光催化性能

聚氯乙烯（PVC）在270℃真空环境中经热处理脱除HCl得到具有共轭结构的PVC衍生物（CDPVC）。纳米TiO₂与CDPVC （质量比为2∶1）经高能球磨复合得到纳米TiO₂/CDPVC复合材料。采用TEM、XRD、XPS、FTIR、SEM和Raman等对纳米TiO₂/CDPVC复合材料进行了分析表征,并采用罗丹明B （Rh B）的光催化降解反应和K₂Cr₂O₇的光催化还原反应评价其可见光催化活性及稳定性。结果表明,TiO₂与CDPVC经高能球磨复合后形成了Ti—O—C结构,该结构有利于提高纳米TiO₂/CDPVC复合材料的可见光吸收能力和光生电子/空穴分离效率。与纳米TiO₂和普通研磨的TiO₂-CDPVC相比,纳米TiO₂/CDPVC复合材料具有较高的可见光催化活性和良好的可见光催化稳定性。其可见光催化机制是CDPVC吸收光子产生光生电子-空穴对,并容易将光生电子注入到TiO₂的导带中,CDPVC内光生电子和TiO₂导带上的光生电子（e_CB-）被吸附在材料表面上的氧捕获产生·O₂-自由基,·O₂-自由基可以直接降解RhB分子,直至最后降解生成H₂O和CO₂。      

研磨-焙烧法制备La2O3/BiOCl复合光催化剂及其对高浓度染料降解性能

首先利用沉淀法合成了BiOCl纳米片, 然后利用研磨-焙烧法将La₂O₃纳米颗粒复合到BiOCl纳米片中, 制备了一系列La₂O₃/BiOCl复合光催化剂(La₂O₃: 1wt%、2wt%、4wt%、8wt%)。运用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、傅里叶红外光谱(FT-IR)和光致发光(PL)谱等对样品的晶相、光吸收和表面性能等进行了表征。以紫外灯(λ = 254 nm)为光源, 评价了所制备样品光催化降解高浓度染料酸性橙II(40×10^-6)的活性。结果表明, 经过研磨-焙烧后该系列催化剂均具有较好的结晶性能, 同时2~5 nm的La₂O₃纳米粒子粘附在BiOCl纳米片表面。200℃焙烧制备的1wt%La₂O₃/BiOCl催化剂具有丰富的表面羟基, 对染料表现出较强的吸附性能。该催化剂表现了最高的光催化活性, 活性为纯BiOCl的2.4倍。另外, La₂O₃/BiOCl中的La³⁺提供的氧化-还原势阱可能捕获光生电子, 从而阻止了光生电子(e^-)和空穴(h⁺)的复合, 有利于光催化活性的提高。     

改性煤矸石/TiO2光催化剂的制备及其光催化性能研究

采用溶胶-凝胶法,以盐酸蚀刻煤矸石(mCG)为吸附剂,制备了煤矸石复合TiO_2光催化剂(mCG/TiO_2)。采用扫描电镜、透射电镜、红外光谱、X射线衍射和紫外-可见漫反射对复合材料进行表征。以罗丹明B为模拟污染物,考察了制备条件对其光催化活性的影响,结果表明:当mCG质量含量为15%,在500℃下煅烧2h得到的mCG/TiO_2复合材料对罗丹明B光催化降解率最高,在紫外光照射下,75min内对初始浓度为10mg/L的罗丹明B降解率达到97.3%;可见光下180min内降解率达到90.24%。活性物质捕获实验证明·OH为光催化体系的主要活性物质。     

Bi_2S_3-BiOCl/煤矸石复合光催化剂的制备及光催化性能

以表面改性煤矸石粉、Bi(NO_3)_3·5H_2O和NH_4Cl为原料,采用超声化学法制备了BiOCl/煤矸石前驱体;并通过BiOCl/煤矸石前驱体和硫代乙酰胺(TAA)的阴离子交换反应,原位制备了Bi_2S_3-BiOCl/煤矸石复合光催化剂。利用XRD和SEM对Bi_2S_3-BiOCl/煤矸石复合光催化材料的结构及表面形貌进行了表征,并以可见光为光源,甲基橙为目标降解物,对其光催化活性进行了研究。结果表明:在可见光辐照下,Bi_2S_3-BiOCl/煤矸石复合光催化剂表现出较高的光催化降解能力,这是由于Bi_2S_3与BiOCl复合后形成的异质结促进了光生电子和光生空穴的分离,抑制了它们的复合。     

Oxygen vacancies facilitated photocatalytic detoxification of three typical contaminants over graphene oxide surface embellished BiOCl photocatalysts

A conventional solvothermal way was used to synthesize graphene oxide (GO)/BiOCl photocatalytic nanomaterials with enhanced photocatalytic performance. Due to the introduction of GO, there are intuitive changes in morphology, indicating that GO can guide the growth of GO/BiOCl catalysts. The results of X-ray photoelectron spectroscopy (XPS) and Raman show that a strong chemical interaction occurs around GO and BiOCl. The results of trapping experiments show that O₂^– is the major active species. XPS analysis confirms that the 0.75% GO/BiOCl produces the highest level of oxygen vacancies (OVs). All the GO/BiOCl photocatalysts possess better photocatalytic properties than the neat BiOCl, and 0.5% GO/BiOCl exhibits the highest photoactivity. The photocatalytic activity of 0.5% GO/BiOCl composite for detoxification of rhodamine B (RhB) and tetracycline (TC) under visible light illumination is 4.6 and 6.3 times of that on the reference BiOCl, separately, the photocatalytic activity of 0.5% GO/BiOCl for detoxication of perfluorooctanoic acid (PFOA) is 1.25 times of that of the single BiOCl under UV light illumination, which can be credited to the high separation rate of carriers and the strong interaction between GO and BiOCl. Combining with the results, a separation and transfer mechanism of carriers was revealed.     

Size-controlled BiOCl–RGO composites having enhanced photodegradative properties

Visible light-active bismuth oxychloride–reduced graphene oxide (BiOCl–RGO) composite photocatalysts were synthesised using a hydrothermal method at low temperature, and at a low cost. This approach reduced the recombination of electron–hole pairs and thereby provided more efficient photocatalysts. The size of BiOCl structure was controlled by polyvinylpyrrolidone (PVP) addition. Furthermore, formation of nanosized BiOCl sheets and BiOCl–RGO composites were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Fabricated BiOCl–RGO composite with PVP exhibited better photocatalytic activity than pure BiOCl grown with and without PVP towards degradation of Rhodamine B (RhB). It was found that the composite photocatalyst degrades RhB completely within 310 min as compared with several hours for pure BiOCl. The improved photocatalytic performance of BiOCl–RGO composite was attributed to its high specific surface area (22.074 m² g^?1 and existence of polar surfaces, compared with 9.831 m² g^?1 for pure BiOCl). The analyses indicated that RGO helped to reduce recombination losses and improve electron transport. It also showed that presence of polar surfaces improved photocatalytic activity of BiOCl. Hence, BiOCl–RGO composite is a promising catalyst for the degradation of organic pollutants under visible light and could be used in applications such as water purification devices.     

Decoration of Au nanoparticles onto BiOCl sheets for enhanced photocatalytic performance under visible irradiation for the degradation of RhB dye

Plasmonic photocatalysts are promising candidates for use in the degradation of pollutants. Their ability to degrade a wide range of organic pollutants stems from key properties such as high visible light absorption, the ability to generate hot electrons and the formation of a Schottky barrier that facilitates effective separation of charge carriers. In the present work, we synthesised bismuth oxychloride sensitised with gold nanoparticles (NPs, 20–50 nm) via a two-step chemical process at low temperature. The fabricated Au/BiOCl powder was evaluated in the degradation of Rhodamine B (RhB) dye under visible light irradiation. The photocatalytic performance of the Au/BiOCl hybrid was almost double that of pristine BiOCl. This enhanced performance was attributed to electron transfer from BiOCl to Au via the formation of heterojunctions at the BiOCl/Au interface. Additionally, the surface plasmon resonance effect of the Au NPs provided high optical absorbance in the visible spectrum. TEM (transmission electron microscopy) analysis indicated the presence of polar (010) facets on the BiOCl sheets, which also contributed to dramatically improving their photocatalytic performance. The degradation time of the Au/BiOCl hybrid was 200 min compared with 320 min for pure BiOCl.     

Carbon quantum dots/attapulgite nanocomposites with enhanced photocatalytic performance for desulfurization

Carbon quantum dots (CQDs)/attapulgite (ATP) nanocomposite was prepared by a simple impregnation method. The ATP was initially modified with hydrochloric acid solution, which favored for the combination of CQDs due to the generation of hydroxyl group on the surface. XRD shows the decrease of interplanar spacing of ATP (1 1 0) plane, suggesting that the CQDs are immobilized on the surface of ATP. UV–Vis shows that the absorption peak of modified ATP is apparently red-shifted and the absorbance intensity of CQDs/ATP is higher than others. FT-IR and XPS show that the CQDs are immobilized on the surface of ATP through hydroxylation reaction. TEM shows that the average diameter of CQDs nanoparticles is about 5 nm and they are coated on the surface of ATP uniformly. The CQDs/ATP nanocomposite was employed as catalyst for photocatalytic degradation of dibenzothiophene (DBT) in model gasoline under visible light irradiation. The influence of the mass ratio of CQDs to ATP on desulfurization performance was investigated. The desulfurization rate of DBT could reach 93% when the mass ratio of CQDs/ATP is 3:10. The enhanced photocatalytic oxidative desulfurization was attributed to the sensitizing effect and up-conversion property of CQDs.     

g-C3N4/高岭土复合材料的制备及其光催化性能研究

以水洗高岭土为载体, 采用盐酸对g-C₃N₄进行质子化处理, 通过浸渍法制备了g-C₃N₄/高岭土复合光催化材料。采用X射线衍射(XRD)、场发射扫描电镜(FESEM)和紫外-可见吸收光谱(UV-Vis)等手段对复合材料的晶体结构、微观形貌和光学性能进行了表征, 并以罗丹明B为目标降解物, 研究了复合材料在可见光下的光催化性能。结果表明: 当高岭土和g-C₃N₄的质量配比为6︰3时, g-C₃N₄/高岭土具有较优的光催化性能, 其光催化速率是纯g-C₃N₄的8.62倍; 高岭土和g-C₃N₄通过静电吸引力紧密结合在一起, 该复合结构能够有效地降低光生电子和空穴的复合几率, 改善了纯g-C₃N₄光催化材料的吸附性能, 进而有效提高了其光催化性能。     

Synthesis of heterostructured In2O3/BiOCl powders and their visible-light-driven photocatalytic activity for the degradation of Rhodamine B

Heterostructured In₂O₃/BiOCl powders were synthesized by chemical coprecipitation method at room temperature followed by thermal treatment at 400 °C for 2 h. The TEM results confirmed the formation of sheet-like BiOCl nanostructures with the thickness of ca. 5–7 nm. In order to investigate the effect of In₂O₃ on the photocatalytic activity of heterostructured powders, the amount of In₂O₃ was varied from 0 wt% to 14 wt%. Adsorption and photocatalytic activity of the samples were evaluated for the degradation of Rhodamine B (RhB) in the dark and under visible light irradiation, respectively. The heterostructured In₂O₃/BiOCl powders showed high adsorption capacity and enhanced photocatalytic activity compared to P25 and pure BiOCl. Based on the results obtained in this study, the mechanism for the enhancement of photocatalytic activity of heterostructured In₂O₃/BiOCl powders is discussed. 10 wt% In₂O₃/BiOCl composite also exhibited good cycle performance for the degradation of RhB under visible light irradiation.