Constructing recyclable photocatalytic BiOBr/Ag nanowires/cotton fabric for efficient dye degradation under visible light

In this study, a highly-efficient photocatalytic and recyclable BiOBr/Ag nanowires (AgNW)/cotton fabric (CF) composite was fabricated by successive ionic layer adsorption and reaction (SILAR) for rapid treatment of dye wastewater. The integration of AgNW and BiOBr aims to establish a channel for faster and easier charge transfer to enhance the photocatalytic performance. The chemical structure and morphology of BiOBr/AgNW/CF, as well as its photo-degradation of Rhodamine B (RhB) under visible light radiation were explored. Results reveal that BiOBr/AgNW/CF exhibits remarkably enhanced photocatalytic activity over BiOBr/CF, which degrades 97 % of RhB within 90 min. BiOBr/AgNW/CF still maintains 88 % of photocatalytic degradation capacity after five reusing cycles due to the effective encapsulation of BiOBr that protects AgNW from oxidation. Photoluminescence, electron spin resonance, and free radical trapping experiments confirm that the separation efficiency of photo-generated electron-hole pairs plays an important role in improving photocatalytic performance. In all, this work exhibits great potential in the development of textile-based photocatalytic materials that integrates two significant merits, the high degradation efficiency and easy recovery.     

Enhanced photocatalytic activity and stability of AgBr/BiOBr/graphene heterojunction for phenol degradation under visible light

In this work, we have reported synthesis of AgBr/BiOBr photocatalyst supported on graphene (Gr) using facile precipitation method. AgBr/BiOBr/Gr was characterized using various spectral techniques like FESEM, TEM, XRD, FTIR, XPS, Raman and PL analyses. AgBr/BiOBr/Gr had improved visible light absorption. PL studies indicated the reduction in recombination of photogenerated electron hole pair of AGBr/BiOBr/Gr. AFM analysis confirmed the thickness of AGBr/BiOBr/Gr was less than 8.0 nm. The higher dispersibility of photocatalyst was ascertained by Tyndall effect. AgBr/BiOBr/Gr photocatalyst was effectively used for the photodegradation of phenol from simulated water. The phenol degradation process was remarkably influenced by adsorption process. The concurrent adsorption and photocatalytic was effective for degradation of phenol. The phenol was completely mineralized into CO₂ and H₂O in 6 h. The degradation process followed pseudo first order kinetics. The results confirmed that integration of AgBr/BiOBr with graphene caused an increase in photocatalytic activity due to reduced recombination of photogenerated electron hole pair and electron sink behavior of graphene for photogenerated electrons of BiOBr. AgBr/BiOBr/Gr photocatalyst displayed significant stability and recyclability for ten catalytic cycles.     

A series of highly efficient photocatalysts for organic contaminants degradation under visible light irradiation

Antimonic acid and N-doped antimonic acid, solid acids with d(10) electron configuration, are reported as novel photocatalysts for rhodamine B (RhB) degradation under visible light irradiation. They show much higher activities in comparison with P25 and photolysis. However, the extent of degradation abilities for RhB was not consistent with the formation rate of the active ˙OH radicals under visible light irradiation.     

Photocatalytic degradation of methylene blue over N-doped MnWO4 under visible light irradiation

In recent years, the transition-metal tungstate materials with formula MWO₄ have attracted much attention in photocatalytic environmental purification due to their interesting structural and optical properties. Among the others, manganese tungstate (MnWO₄) has attracted particular attention because of its appropriate bandgap energy (2.67 ​eV) with tunable optical and electrical properties, chemical stability, and low cost which makes a suitable photocatalyst. Nevertheless, the manganese tungstate (MnWO₄) based materials are less explored as visible light responsive photocatalysts for wastewater purification. Hence, both parent and N-doped MnWO₄ are synthesized by a hydrothermal method with different nitrogen contents (5, 10, and 15 ​mol%). The as-prepared photocatalysts were characterized by XRD, SEM-EDS, TEM-SAED, FT-IR, UV–Vis DRS, XPS and PL techniques. The photocatalytic activities of the synthesized samples were evaluated by degradation of methylene blue (MB) dye under the visible light irradiation. All the N-doped MnWO₄ samples exhibited enhanced visible-light photocatalytic activity compared to the parent MnWO₄, and the optimal dopant amount of nitrogen was 15 mol% for the best photocatalytic activity. The active species generated during the process of MB degradation are investigated by scavenging experiments. Further, the reusability of the 15 ​mol% N-doped MnWO₄ photocatalyst was examined in three consecutive catalytic runs.     

Fabrication of nanoporous polymeric crystalline TiO2 composite for photocatalytic degradation of aqueous organic pollutants under visible light irradiation

A nanoporous polymeric crystalline TiO₂ composite (TiO₂/PDVB‐MA) has been successfully synthesized through an in situ synthesis method using divinylbenzene (DVB), methacrylic acid (MA) and tetrabutyl titanate. The experimental results showed that TiO₂ nanoparticles composed of the mixture phases of anatase and rutile were homogeneously dispersed into the PDVB‐MA support. The TiO₂/PDVB‐MA composite was used as photocatalyst for Rhodamine B (RhB), bisphenol A and 2,4,6‐trichlorophenol degradation under visible light irradiation. More interestingly, the excellent photocatalytic performance of the composite was observed with regard to RhB and bisphenol A, which might be ascribed to the synergistic effect between TiO₂ nanoparticles and PDVB‐MA. Moreover, TiO₂/PDVB‐MA composite could be recycled at least four times in the removal of RhB, suggesting that it is a promising photocatalyst to catalyze the degradation of organic pollutants under visible light irradiation.     

Au/BiOBr/石墨烯复合物的制备及其苯酚降解光催化性能

采用水热法和多巴胺还原法制备了Bi OBr、Bi OBr/石墨烯和Au/Bi OBr/石墨烯光催化剂,并利用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、光致发光光谱(PL)和紫外-可见漫反射光谱(UV-vis DRS)等方法表征其形貌、相结构、光谱吸收性质以及组成结构。在可见光照射下,通过对水相中苯酚的降解,考察了Au/Bi OBr/石墨烯复合光催化剂活性。结果表明,由于量子效率的提高、带隙能的降低(2.25 e V)以及Au表面等离子体共振,复合光催化剂表现出比纯Bi OBr更高的光催化活性,Au/Bi OBr/石墨烯复合物在180 min内对苯酚降解率可达到64%。     

BiVO_4/MOF复合材料的合成及其光催化性能

通过简单溶剂热法制备了一种新型复合光催化剂BiVO_4/M IL-53(Fe);运用XRD、SEM/EDS、FT-IR、N_2吸附-脱附和UV-vis DRS等手段对其进行表征,并对其光催化降解RhB活性进行了研究,提出了相应的光催化降解RhB的可能机理。结果表明,相较于单一BiVO_4材料,复合催化剂的比表面积增大,且其光催化效率相较于纯BiVO_4和MIL-53(Fe)也有了较大的提高;其中,BF-2复合材料的光催化活性最高,分别约为纯MIL-53 (Fe)和BiVO_4的5. 2倍和8. 1倍。同时,BiVO_4/MIL-53(Fe)复合光催化剂经过四次循环实验后,仍能保持较稳定的光催化活性和结构。     

BiOBr/BiOI复合体的制备及可见光催化性能

以硝酸铋、碘化钾、溴化钠和聚乙二醇-400为主要原料,利用水热法制备出具有较小粒径的BiOBr/BiOI复合体,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、紫外可见漫反射(DRS)等测试手段对样品的形貌、物相组成进行了表征。以罗丹明B为模拟污染物,研究了可见光下所制备样品的光催化性能。结果表明:BiOBr/BiOI复合体的光催化性能高于单一的BiOBr和BiOI,光照80 min后罗丹明B的降解效率可达95.6%。     

Photocatalytic degradation of methyl red by porous zinc hydroxide under visible light irradiation

In the present study, porous zinc hydroxide was successfully prepared via a simple sol–gel route. The synthesized porous zinc hydroxide was characterized using scanning electron microscopy (SEM), X‐ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) techniques. In addition, the prepared porous zinc hydroxide was studied as a photocatalyst for the degradation of methyl red. The degradation behavior of porous zinc hydroxide was investigated systematically. The experimental results showed that the obtained porous zinc hydroxide displayed excellent degradation efficiency (89%) under visible light irradiation. Thus, porous zinc hydroxide can be used as an effective photocatalyst for the degradation of methyl red, which can be used for industrial wastewater treatment.     

Synthesis of graphitic carbon nitride-based photocatalysts for hydrogen evolution under visible light

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Enhanced photocatalytic activity of SiC modified by BiVO4 under visible light irradiation

SiC-BiVO₄-P and SiC-BiVO₄-H composites have been prepared by precipitation method and hydrothermal method, respectively. Rod-like BiVO₄ particles dispersed on the surface of micro-sized SiC particles homogeneously in SiC-BiVO₄-H. Due to the formed heterostructure between BiVO₄ and SiC, photo-generated electrons and holes were effectively separated. Under visible light irradiation, SiC-BiVO₄-H exhibited the best performance for photocatalytic oxidation of Rhodamine B, achieved about 7.5 times improvement in photocatalytic degradation rate constants compared with that of the pristine SiC powder. The possible photocatalysis mechanism of SiC/BiVO₄ related to the band positions of the semiconductors under visible light irradiation was also discussed in detail. In addition, the radicals trapping experiments revealed that all three radicals (holes, OH, and O₂^?) play an important role in the Rhodamine B degradation.     

Photocatalytic degradation of trichloroethylene over BiOCl under UV irradiation

In this study, BiOCl samples were synthesized under different pH values and characterized by XRD, SEM, UV‐vis DRS, BET, photoelectrochemical measurement and PL. The photocatalytic performances of the as‐prepared samples were evaluated through the decomposition of trichloroethylene (TCE) under UV irradiation. The influences of several parameters such as solution pH and common inorganic anions on TCE removal were investigated. Results indicated that BiOCl‐0.6 exhibited better photocatalytic performance than BiOCl‐6.0 because of its higher migration ability of photo‐induced carrier. The photocatalytic degradation of TCE over BiOCl‐0.6 followed pseudo first‐order kinetics and appeared to be more efficient in acidic solution than in alkaline. TCE was almost completely dechlorinated in 120 minutes. The inhibiting effect of naturally occurring anions was in the order of HCO₃^‐ >SO₄^2‐ >NO₃^‐, while Cl^‐ exhibited a dual effect. Moreover, BiOCl‐0.6 exhibited superior reusability after three cycles of repetition tests.     

g-C_3N_4/BiOBr异质结光催化剂的制备与可见光催化活性

以三聚氰胺作为合成g-C_3N_4纳米片的前躯体,以Bi(NO3)3·5H2O和KBr作为合成BiOBr的原料,采用水热法构建g-C_3N_4/Bi OBr二维异质结可见光催化剂,有效的晶面复合和合适的能带组合有助于增强g-C_3N_4和BiOBr的可见光催化活性。利用X射线衍射(XRD)、透射电镜(TEM)、X射线光电子能谱(XPS)、光致发光光谱(PL)和紫外-可见漫反射光谱(UVvis DRS)等方法表征其结构、光学性质以及组成结构。在可见光(λ420 nm)下以光催化降解RhB来评价合成催化剂的光催化活性,结果表明,g-C_3N_4/BiOBr光催化降解罗丹明B(Rh B)的效率高于单体g-C_3N_4和BiOBr,并对g-C_3N_4/BiOBr增强可见光催化RhB机理进行解释。     

Chalcogen-doped zinc oxide nanoparticles for photocatalytic degradation of Rhodamine B under the irradiation of ultraviolet light

In the present work, the chalcogen (Se²⁺)-doped ZnO nanoparticles (SeZO-NPs) were synthesized using sol-gel precipitation method and tested for photocatalytic degradation of Rhodamine B (RhB). X-ray diffraction pattern of SeZO-NPs showed the hexagonal wurtzite crystal structure regardless of Se concentration. The band edge and defect-level emissions of SeZO-NPs were determined by using the photoluminescence spectra with the excitation source of 370 nm. The bandgap, E_g, of SeZO-NPs was measured from diffused reflectance spectroscopy, which increased from 3.22 to 3.26 eV as Se concentration increased from 0 to 10 wt.%. The highest specific surface area and lowest pore size of 5-SeZO-NPs were observed to be 36.42 m²/g and 13.48 nm, respectively. The photocatalytic degradation of SeZO-NPs was measured under the illumination of ultraviolet (UV) light. The double donor (Se) played an important role toward photodegradation of RhB via reducing the recombination of charge carriers. The highest photocatalytic degradation (98.23%) and mineralization were achieved for the sample 5-SeZO (Se: 5 wt.%). The improved photocatalytic performance of 5-SeZO was attributed to the optimum Se dopant concentration for the production of more reactive oxygen species because of effective separation of charge carriers in UV light.     

Photoassisted degradation of dye pollutants in aqueous TiO2 dispersions under irradiation by visible light

The photoassisted degradation of two dye compounds, erythrosine and rhodamine B, has been investigated in an aqueous TiO₂ dispersion under irradiation by visible light. The compounds can be easily decomposed photochemically by visible light, which provides possibly a new approach for the treatment of dye pollutants in wastewater.     

溴化银/二氧化钛复合材料的可见光催化性能

将硝酸银的乙醇溶液与溶胶凝胶TiO2混合得到前驱体,随后经共沉淀-煅烧制备得到AgBr/TiO2复合材料;采用扫描电镜、X射线衍射仪、X射线光电子能谱仪分析了复合材料的形貌、晶体结构、Ag元素的价态,采用紫外-可见漫反射光谱仪测定了其光吸收性能;进而以甲基橙(MO)的可见光降解为探针反应测定了AgBr/TiO2复合材料的可见光催化性能.结果表明,当前驱体在不同温度下煅烧后,无定形TiO2颗粒逐渐增大,并逐渐转变为锐钛矿结构;担载的AgBr可明显拓展TiO2的可见光吸收范围;Ag物种主要以Ag+形式存在.当煅烧温度为300℃时,复合材料的光催化活性最高,MO的降解率在60min内达到90%以上;随着煅烧温度的增加,催化活性逐渐降低.     

Enhanced photocatalytic degradation of rhodamine B under visible light irradiation on mesoporous anatase TiO2 microspheres by codoping with W and N

Mesoporous anatase TiO₂ microspheres were prepared via solvothermal method. Ammonium tungstate was used as the W source, and ammonia gas flowing in an ammonothermal reactor as the N source for codoping. TiO₂:(W,N) mesoporous microspheres, which were prepared from solvothermal treatment at 160 °C for 16 h and thermal ammonolysis at 500 °C for 2 h after calcination, have high specific surface area of 106 m² g⁻¹. XPS results indicate the presence of N_O, N_i and W⁶⁺ in the codoped mesoporous TiO₂ microspheres. Monodoping with N shifts the absorption band edge of anatase TiO₂ from ultraviolet region to visible region. Although codoping with W makes the visible light absorbance decrease a little, the photocatalytic degradation of a cationic dye rhodamine B (RhB) on mesoporous TiO₂:(W,N) microspheres is increased to 1.7 times of that on mesoporous TiO₂:N microspheres. This may due to decreasing recombination centers by W-doping charge compensation.     

Reduced-graphene-oxide-wrapped BiOI-AgI heterostructured nanocomposite as a high-performance photocatalyst for dye degradation under solar light irradiation

Solar photocatalytic water treatment has emerged as a promising way to provide clean water. However, most traditional photocatalysts (TiO₂, ZnO, etc.) are active only under ultraviolet light and have high recombination rates of photoinduced electron-hole pairs; therefore, they are not sufficient to fulfill all of the demands of practical applications. This problem could be overcome by developing highly solar-light-active and durable heterostructured photocatalysts. In this study, a new solar-light-active heterostructured reduced graphene oxide (RGO)/BiOI/AgI photocatalyst was successfully fabricated through a simple precipitation method. The resultant heterostructured RGO/BiOI/AgI nanocomposite exhibited extraordinary photocatalytic performance in the degradation of rhodamine B (RhB) under simulated sunlight irradiation. The measured rate constant of the RGO/BiOI/AgI nanocomposite was six times higher than that of bare BiOI nanostructures. Its extraordinary capacity for harvesting full-spectrum light and long-term stability makes the RGO/BiOI/AgI nanocomposite a potential photocatalyst for environmental remediation.     

纳米TiO2光催化分解罗丹明B的动力学分析

锐钛矿型TiO2禁带宽度为3 2eV,在波长小于387nm的紫外辐射激发下,价带电子跃迁到导带,光生电子和空穴分离,与表面接触组分可发生一系列氧化还原反应,可将有机污染物降解为简单的无机化合物[1]。TiO2微粒粒径的降低(几十纳米),吸收光谱发生蓝移,催化活性随粒径的减小而增强[2,3]。纳米TiO2对罗丹明B的光催化分解过程与罗丹明B在TiO2表面的吸附有关[4]。本文采用自制纳米TiO2在4W紫外灯直接照射下,光分解罗丹明B为表观一级反应,反应速率与罗丹明B起始浓度及催化剂用量有关。1　实验部分纳米TiO2 采用sol gel法制备。分别配制不同…