Highly Efficient Simulated Solar Light-Driven Photocatalytic Degradation of 4-Nitrophenol over CdS/Carbon/MoSx Hybrids

Among the various organic pollutants and industrial chemicals, 4-nitrophenol has been one of the most monitored substances in aqueous environments, due to its enhanced solubility in such systems. This research reports for the first time the microwave-assisted synthesis of CdS/carbon/MoS_x hybrids and the subsequent utilization of such systems as photocatalysts for 4-nitrophenol degradation. The hybrids demonstrated a variable photocatalytic activity, by using a variety of organic substances as precursors for the solvothermal carbonization step. By using ascorbic acid as precursor, the corresponding ternary composite exhibited excellent photocatalytic activity, with the 4-nitrophenol concentration been almost quantitatively decayed within 45 min of irradiation. This could be ascribed due to the generation of a high population of heterojunctions as well as the chemical speciation of Mo-based nanostructures. Such ternary hybrids may be utilized as potential photocatalytic systems in processes, where removal of toxic water-soluble substances is the key issue.     

CeO2/Bi2WO6 Heterostructured Microsphere with Excellent Visible‐light‐driven Photocatalytic Performance for Degradation of Tetracycline Hydrochloride

CeO₂/Bi₂WO₆ heterostructured microsphere with excellent and stable photocatalytic activity for degradation tetracyclines was successfully synthesized via a facile solvothermal route. The photocatalytic experiments indicated that CeO₂/Bi₂WO₆ heterostructured microspheres exhibited enhanced photocatalytic activity compared to pure Bi₂WO₆ in both the degradation of tetracycline hydrochloride (TCH) and rhodamine B (RhB) under visible‐light irradiation. The 1CeO₂/2Bi₂WO₆ exhibited the best photocatalytic activity for degradation of TCH, reaching 91% after 60 min reaction. The results suggested that the particular morphological conformation of the microspheres resulted in smaller size and more uniform morphology so as to increase the specific surface area. Meanwhile, the heterojunction was formed by coupling CeO₂ and Bi₂WO₆ in the as‐prepared microspheres, so that the separation efficiency of photogenerated electrons and holes was dramatically improved and the lifetimes of charge carriers were prolonged. Hence, introduction of CeO₂ could significantly enhance the photocatalytic activity of CeO₂/Bi₂WO₆ heterostructured microspheres and facilitate the degradation of TCH. This work provided not only a principle method to synthesize CeO₂/Bi₂WO₆ with the excellent photocatalytic performance for actual produce, but also a excellent property of the photocatalyst for potential application in photocatalytic treatment of tetracyclines wastewater from pharmaceutical factory.     

ZnO/ZnS Heterostructured Nanorod Arrays and Their Efficient Photocatalytic Hydrogen Evolution

Semiconducting heterostructures have been widely applied in photocatalytic hydrogen evolution due to their variable band gaps and high energy conversion efficiency. As typical semiconducting heterostructures, ZnO/ZnS heterostructured nanorod arrays (HNRAs) have been obtained through a simple anion‐exchange process in this work. Structural characterization indicates that the heterostructured nanorods (HNRs) are all composed of hexagonal wurtzite ZnO core and cubic zinc‐blende ZnS shell. As expected, the as‐obtained one‐dimensional heterostructures not only lower the energy barrier but also enhance the separation ability of photogenerated carriers in photocatalytic hydrogen evolution. Through comparisons, it is found that 1D ZnO/ZnS HNRAs exhibit much better performance in photocatalytic hydrogen evolution than 1D ZnO nanorod arrays (NRAs) and 1D ZnS NRAs. The maximum H₂ production is 19.2 mmol h^?1 for 0.05 g catalyst under solar‐simulated light irradiation at 25 °C and the corresponding quantum efficiency is 13.9 %, which goes beyond the economical threshold of photocatalytic hydrogen evolution technology.     

PdO/TiO2 and Pd/TiO2 Heterostructured Nanobelts with Enhanced Photocatalytic Activity

Heterostructures play an important role not only in the manufacture of semiconductor devices, but also in the field of catalysis. Herein, we report the synthesis of PdO/TiO₂ and Pd/TiO₂ heterostructured nanobelts by means of a simple co‐precipitation method, followed by a reduction process using surface‐modified TiO₂ nanobelts as templates. The as‐obtained heterostructures were characterized by transmission electron microscopy, X‐ray photoelectron spectroscopy, and UV/Vis diffuse reflectance spectroscopy. PdO and Pd nanoparticles with a size of about 1.3 and 1.6 nm were assembled uniformly on the surface of TiO₂ nanobelts, respectively. Compared with TiO₂ nanobelts, PdO/TiO₂ and Pd/TiO₂ hybrid nanobelts exhibit enhanced photocatalytic activity upon UV and visible‐light irradiation. Photoelectrochemical technology was used to study the heterostructure effect on enhanced photocatalytic activity. Our mechanistic investigation revealed that energy‐band matching is the major factor in the observed enhancement of photocatalytic activity.     

In2O3/ZnO heterostructured nanotubes: electrospinning fabrication,characterization, and highly enhanced photocatalytic properties

In₂O₃/ZnO heterostructured nanotubes with cubic In₂O₃ and hexagonal ZnO were successfully synthesized via the combination of electrospinning and calcination process. The as-prepared materials are investigated by using thermogravimetric and differential scanning calorimetry, fourier transform infrared spectroscope, X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscope techniques. The formation mechanism of In₂O₃/ZnO heterostructured nanotubes based on the kinetics of phase separation which results from the decomposition of polyvinyl pyrrolidone during the calcination process is also discussed in detail. The photocatalytic degradation tests reveal that In₂O₃/ZnO heterostructured nanotubes exhibit the highly improved photocatalytic properties compared with the single-component ZnO and In₂O₃ materials.     

Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO₃. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O₂^•−) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.     

p区金属氧化物Ga2O3和Sb2O3光催化降解盐酸四环素性能差异

对沉淀法合成的p区金属氧化物Ga₂O₃和Sb₂O₃紫外光光催化降解盐酸四环素的性能进行了研究,讨论了制备条件对光催化性能的影响。最佳制备条件下得到的Ga₂O₃-900和Sb₂O₃-500样品光催化性能存在巨大差异,通过X射线粉末衍射、傅里叶红外光谱、N2吸附-脱附测试、荧光光谱、拉曼光谱、电化学分析及活性物种捕获实验等对样品进行分析,研究二者光催化降解盐酸四环素的机理,揭示影响光催化性能差异的本质因素。结果表明,Ga₂O₃和Sb₂O₃光催化性能差异主要归结于二者不同的电子和晶体结构、表面所含羟基数量及光催化降解机理。     

Facile Electrospinning of CeO2/Bi2WO6 Heterostructured Nanofibers with Excellent Visible‐light‐driven Photocatalytic Performance

One‐dimensional (1D) CeO₂/Bi₂WO₆ heterostructured nanofibers with a diameter of about 300 nm were successfully synthesized by using a straightforward strategy combining an electrospinning technique with a sintering process. The acquired products were characterized by thermogravimetric and differential scanning calorimetric (TG‐DSC), Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area measurements, and UV/Vis spectroscopy. The obtained CeO₂/Bi₂WO₆ heterostructured nanofibers exhibited an excellent photocatalytic property for the degradation of Rhodamine B (RhB) dye driven by visible light due to the promoted separation of photoelectrons and holes and the large contact area between the photocatalyst and organic pollutant.     

p区金属氧化物Ga2O3和Sb2O3光催化降解盐酸四环素性能差异

对沉淀法合成的p区金属氧化物Ga₂O₃和Sb₂O₃紫外光光催化降解盐酸四环素的性能进行了研究,讨论了制备条件对光催化性能的影响。最佳制备条件下得到的Ga₂O₃-900和Sb₂O₃-500样品光催化性能存在巨大差异,通过X射线粉末衍射、傅里叶红外光谱、N₂吸附-脱附测试、荧光光谱、拉曼光谱、电化学分析及活性物种捕获实验等对样品进行分析,研究二者光催化降解盐酸四环素的机理,揭示影响光催化性能差异的本质因素。结果表明,Ga₂O₃和Sb₂O₃光催化性能差异主要归结于二者不同的电子和晶体结构、表面所含羟基数量及光催化降解机理。     

Tripyridine‐Derivative‐Derived Semiconducting Iodo‐Argentate/Cuprate Hybrids with Excellent Visible‐Light‐Induced Photocatalytic Performance

Through regulating the pH values, a series of iodo‐argentate/cuprate hybrids, [Me₃(4‐TPT)]₄[Ag₆I₁₈] ( 1 , Me₃(4‐TPT)=N,N′,N′′‐trimethyl‐2,4,6‐tris(4‐pyridyl)‐1,3,5‐triazine), [Me₃(4‐TPT)][M₅I₈] (M=Ag/ 2 , Cu/ 2 a ), [Me₃(3‐TPT)][M₅I₈] (Me₃(3‐TPT)=N,N′,N′′‐trimethyl‐2,4,6‐tris(3‐pyridyl)‐1,3,5‐triazine, M=Ag/ 3 , Cu/ 4 ), which exhibit adjustable structural variations with different dimensional structures, have been obtained under solvothermal conditions. They are directed by two types of in situ N‐alkylation TPT‐derivatives (Me₃(4‐TPT) for 1 / 2 / 2 a and Me₃(3‐TPT) for 3 / 4 ) and represent the isolated units ( 1 ), 1D polymeric chain ( 4 ), 2D layered structures ( 2 / 2 a , 3 ) based on diverse metal iodide clusters. These compounds possess reducing band gaps as compared with the bulk β‐AgI and CuI and belong to potential semiconductor materials. Iodocuprates feature highly efficient photocatalytic activity in the sunlight‐induced degradation of organic dyes. The detailed study on the possible photocatalytic mechanism, including radical trapping tests and theoretical calculations, reveals that the N‐alkylation TPT moieties contribute to the narrow semiconducting behavior and effectively inhibit the recombination of photogenerated electron‐hole pairs, which result in an excellent visible‐light‐induced photocatalytic performance.     

Unique Properties of 2 D Layered Titanate Nanosheets as a Building Block for the Optimization of the Photocatalytic Activity and Photostability of TiO2‐Based Nanohybrids

In comparison with the hybridization with 0D TiO₂ nanoparticle, 2D layered TiO₂ nanosheets are much more effective in the improvement of the photocatalytic activity and photostability of semiconducting compounds. The 2D TiO₂–Ag₃PO₄ nanohybrid described in this paper shows a greater decrease in the electron‐hole recombination upon hybridization and a stronger chemical interaction between the components than the 0D homologue. This result confirms the benefits of 2D layered TiO₂ nanosheets as a building block for efficient hybrid‐type photocatalyst materials.     

Enhanced photocatalytic activities of TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> nanohybrids immobilized on cement-based materials for dye degradation

Using cement-based material as a matrix for photocatalytic hybrids is an important development for the large-scale application of photocatalytic technologies. In this work, photocatalytic activity of nanosized hybrids of TiO₂/SiO₂ (nano-TiO₂–SiO₂) for degradation of some organic dyes on cementitious materials was highlighted. For this purpose, an optimal inorganic sol–gel precursor was firstly applied to prepare the composites of nano-TiO₂–SiO₂ which was characterized by XRD, SEM and UV–Vis. Then, a thin layer was successfully coated on white Portland cement (WPC) blocks using a dipping process in a nano-TiO₂–SiO₂ solution. The effect of nano-TiO₂–SiO₂-coated WPC blocks on photocatalytic decomposition of three dyes, including Malachite green oxalate (MG), Methylene blue (MB) and Methyl orange (MO) were studied under UV irradiation and monitored by chemical oxygen demand tests. The results showed an increase in photocatalytic effects which depends on the structure and pH of the applied cement.     

Alloyed ZnS–CuInS2 Semiconductor Nanorods and Their Nanoscale Heterostructures for Visible‐Light‐Driven Photocatalytic Hydrogen Generation

A promising photocatalytic system in the form of heterostructured nanocrystals (HNCs) is presented wherein alloyed ZnS–CuInS₂ (ZCIS) semiconductor nanorods are decorated with Pt and Pd₄S nanoparticles. This is apparently the first report on the colloidal preparation and photocatalytic behavior of ZCIS–Pt and ZCIS–Pd₄S nanoscale heterostructures. Incorporation of Pt and Pd₄S cocatalysts leads to considerable enhancement of the photocatalytic activity of ZCIS for visible‐light‐driven hydrogen production.     

g-C3N4/Bi2O2CO32D纳米片复合材料的制备及可见光催化性能研究

采用自组装和化学沉淀法分别制得两种可见光驱动复合材料石墨相氮化碳/碳酸氧铋(g-C_3N_4/Bi_2O_2CO_3).采用X射线衍射光谱(XRD),紫外可见光谱、扫描电镜(SEM)、N_2吸附、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,制备方法对纳米复合材料的晶相、形态及光学性能没有影响,但是影响g-C_3N_4和Bi_2O_2CO_3之间的相互作用力,导致光生电子-空穴对的分离速率存在显著差异.以可见光驱动苯酚和罗丹明B的降解实验为探针反应检测催化剂的光催化性能.实验结果表明自组装法得到的异质结催化剂中相互作用力更强,催化效果最高.O_2-是罗丹明B降解反应的主要活性物种,染料的光敏化、Bi_2O_2CO_3与g-C_3N_4综合效应,导致光生载流子电荷分离效率更高.     

Effcient Removal Phenol Red over Ternary Heterostructured Ag-Bi2MoO6/BiPO4 Composite Photocatalyst

The fabrication of multicomponent composite systems may provide bene ts in terms of charge separation and the retardation of charge pair recombination. In this work, a ternary heterostructured Ag-Bi₂MoO₆/BiPO₄ composite was fabricated through a low-temperature solution-phase route for the rst time. The XRD, SEM, EDX and XPS results indicated the prepared sample is a three-phase composite of BiPO₄, Bi₂MoO₆, and Ag. Ag nanopar-ticles were photodeposited on the surface of Bi₂MoO₆/BiPO₄ nanosheets, which not only increase visible-light absorption via the surface plasmon resonance, but also serve as good electron acceptor for facilitating quick photoexcited electron transfer. The interface between Bi₂MoO₆ and BiPO₄ facilitates the migration of photoinduced electrons from Bi₂MoO₆ to BiPO₄, which is also conductive to reduce the recombination of electron-holes. Thus, the ternary heterostructured Ag-Bi₂MoO₆/BiPO₄ composite showed signi cant photocatalytic activity, higher than pure Bi₂MoO₆, BiPO₄, and Bi₂MoO₆/BiPO₄. Moreover, the possible photocatalytic mechanism of the Ag-Bi₂MoO₆/BiPO₄ heterostructure related to the band positions of the semiconductors was also discussed. In addition, the quenching effects of di erent scavengers revealed that the reactive ·OH and O₂^·- play a major role in the phenol red decolorization.     

In Situ Corrosion Fabrication of NaNbO3/Nb3O7F Heterojunctions with Optimized Band Realignment for Enhanced Photocatalytic Hydrogen Evolution

Heterostructured photocatalysis is a significant issue owing to the unique band alignment, improved spectrum absorption, and enhanced photocatalytic activity. However, the construction of uniform, controllable, and effective heterojunctions is still a huge challenge. Herein, NaNbO₃/Nb₃O₇F heterojunctions are fabricated through an in situ corrosion technique for the first time. The influence of phase transformation on the hydrogen evolution reaction (HER) activity is investigated systematically in terms of photocatalytic water splitting for H₂ production. Interestingly, the band realignment and good interfacial contact endow the NaNbO₃/Nb₃O₇F heterojunctions with a high HER activity (43.3 mmol g⁻¹ h⁻¹), which is about 2.4 times that of pure Nb₃O₇F and 1.36 times that of pure NaNbO₃. The results may provide some new insights into the corrosion technique and HER activity of novel heterostructured catalysts.     

Enhanced Photocatalytic Performance of ZnO Nanorods Coupled by Two‐Dimensional α‐MoO3 Nanoflakes under UV and Visible Light Irradiation

We exploit the utilization of two‐dimensional (2D) molybdenum oxide nanoflakes as a co‐catalyst for ZnO nanorods (NRs) to enhance their photocatalytic performance. The 2D nanoflakes of orthorhombic α‐MoO₃ were synthesized through a sonication‐aided exfoliation technique. The 2D MoO₃ nanoflakes can be further converted to substoichiometric quasi‐metallic MoO_3?x by using UV irradiation. Subsequently, 1D–2D MoO₃/ZnO NR and MoO_3?x/ZnO NR composite photocatalysts have been successfully synthesized. The photocatalytic performances of the novel nanosystems in the decomposition of methylene blue are studied by using UV‐ and visible‐illumination setup. The incorporated 2D nanoflakes show a positive influence on the photocatalytic activity of the ZnO. The obtained rate constant values follow the order of pristine ZnO NR<MoO₃/ZnO NR<MoO_3?x/ZnO NR composites. The enhancement of the photocatalytic efficiency can be ascribed to a fast charge carrier separation and transport within the heterojunctions of the MoO₃/ZnO NRs. In particular, the best photocatalytic performance of the MoO_3?x/ZnO NR composite can be additionally attributed to a quasi‐metallic conductivity and substoichiometry‐induced mid‐gap states, which extend the light absorption range. A tentative photocatalytic degradation mechanism was proposed. The strategy presented in this work not only demonstrates that coupling with nanoscale molybdenum oxide nanoflakes is a promising approach to significantly enhance the photocatalytic activity of ZnO but also hints at new type of composite catalyst with extended applications in energy conversion and environmental purification.     

凹凸棒石/g-C3N4-AgFeO2复合材料制备及其光催化性能

以凹凸棒石(简称凹土,ATP)为基体,通过原位化学法一步直接合成g-C_3N_4薄层材料,并将其有效固载于凹土表面(ATP/gC_3N_4),再通过原位沉淀法引入不同比例AgFeO_2纳米颗粒,构筑系列兼具磁分离特性和高效光催化活性的ATP/g-C_3N_4-AgFeO_2-Y复合光催化剂(Y=wATP/g-C_3N_4/(wATP/g-C_3N_4+wAg FeO_2)×100%,表示ATP/g-C_3N_4在ATP/g-C_3N_4-AgFeO_2复合材料中所占的质量百分数)。采用XRD、SEM、BET、UV-Vis、PL和ICP表征其结构和物化性能,以酸性红G(ARG)为目标降解物,研究其光催化性能。研究发现:通过形成Si-O-C键,g-C_3N_4薄层被均匀固定在凹土表面;AgFeO_2纳米颗粒均匀沉积于ATP/g-C_3N_4表面并形成Z型异质结,ATP/gC_3N_4-AgFeO_2-Y具有比ATP/g-C_3N_4和AgFeO_2更优异的可见光光催化性能,且随着ATP/g-C_3N_4含量的增大呈先升高而后下降的趋势;当Y=57%时复合材料的性能最佳,ATP/g-C_3N_4-AgFeO_2-57%对20 mg·L-1酸性红G的降解率可达97.4%,循环4次使用后,降解率仍保持94.2%。通过自由基捕获实验研究了光催化反应机理,发现·O2-是光催化过程的主要活性物种。     

ZnIn2S4 flowerlike microspheres embedded with carbon quantum dots for efficient photocatalytic reduction of Cr(VI)

Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge. We herein show the synthesis of ZnIn₂S₄/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method. The ZnIn₂S₄/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn₂S₄. With a content of only 0.5 wt % carbon quantum dots, 93% of Cr(VI) is reduced under visible-light irradiation at 40 min. As a co-catalyst, the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers, consequently enhancing the photocatalytic and photoelectrochemical activity.     

Interfacial engineering of graphitic carbon nitride (g-C3N4)-based metal sulfide heterojunction photocatalysts for energy conversion: A review

As one of the most appealing and attractive technologies, photocatalysis is widely used as a promising method to circumvent the environmental and energy problems. Due to its chemical stability and unique physicochemical, graphitic carbon nitride (g-C₃N₄) has become research hotspots in the community. However, g-C₃N₄ photocatalyst still suffers from many problems, resulting in unsatisfactory photocatalytic activity such as low specific surface area, high charge recombination and insufficient visible light utilization. Since 2009, g-C₃N₄-based heterostructures have attracted the attention of scientists worldwide for their greatly enhanced photocatalytic performance. Overall, this review summarizes the recent advances of g-C₃N₄-based nanocomposites modified with transition metal sulfide (TMS), including (1) preparation of pristine g-C₃N₄, (2) modification strategies of g-C₃N₄, (3) design principles of TMS-modified g-C₃N₄ heterostructured photocatalysts, and (4) applications in energy conversion. What is more, the characteristics and transfer mechanisms of each classification of the metal sulfide heterojunction system will be critically reviewed, spanning from the following categories: (1) Type I heterojunction, (2) Type II heterojunction, (3) p-n heterojunction, (4) Schottky junction and (5) Z-scheme heterojunction. Apart from that, the application of g-C₃N₄-based heterostructured photocatalysts in H₂ evolution, CO₂ reduction, N₂ fixation and pollutant degradation will also be systematically presented. Last but not least, this review will conclude with invigorating perspectives, limitations and prospects for further advancing g-C₃N₄-based heterostructured photocatalysts toward practical benefits for a sustainable future.