Preparation of nanocrystalline TiO<Subscript>2</Subscript> powders for photocatalytic oxidation of phenol

Nanocrystalline TiO₂ powders in the anatase, rutile, and mixed phases prepared by hydrolysis of TiCl₄ solution were of ultrafine size (<7.2 nm) with high specific surface areas in the range 167 to 388 m²/g. In the photocatalytic degradation of phenol as model reaction, the photocatalytic properties of TiO₂ nanoparticles were evaluated by use of UV–vis absorption spectroscopy and total organic carbon (TOC) content. The synthetic mixed-phase TiO₂ powder calcined at 400 °C had higher activity than pure anatase or rutile; it degraded more than 90% phenol to CO₂ (evaluated by TOC) after irradiation with near UV light for 90 min at a catalyst loading of 0.4 g/L. The TOC results indicated that rutile TiO₂ crystallites of particle size 7.2 nm resulted in much better photocatalytic performance than particles of larger size. This result suggested that some intermediates, not determined by UV–vis absorption spectroscopy, existed in the solution after the photocatalytic process over the rutile TiO₂ photocatalysts of larger crystallite size.     

α-Fe2O3 supported Bi2WO6 for photocatalytic degradation of gaseous benzene

The Bi₂WO₆/α-Fe₂O₃ composite photocatalyst was synthesized by using goethite as a precursor through hydrothermal-calcination method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis reflection spectrometer (DRS), X-ray photoelectron spectroscopy (XPS) and N₂ adsorption-desorption measurement (BET). These results indicated that the self-made composite photocatalysts had excellent catalytic performance of degradation of gaseous benzene. When benzene initial concentration at 50 mg/m³, over the α-FeOOH/Bi₂WO₆ with molar mass of 0.8:1, calcined at 350 °C for 2 h and the pH of precursor solution was 3, the benzene degradation rate reached 71.9% and the mineralization efficiency reached 67.7% after 220 min UV irradiation, respectively. The h⁺ and O₂⁻ generated in the photocatalytic system should be played a pivotal role for the enhanced photodegradation performance of gaseous benzene.     

Precise regulation of Ultra-thin platinum decorated Gold/Graphite carbon nitride photocatalysts by atomic layer deposition for efficient degradation of Rhodamine B under simulated sunlight

Atomic Layer Deposition (ALD) precise controlling ultra-thin platinum (Pt) modified Graphite carbon nitride (g-C₃N₄) photocatalysts, which had been doped with gold nanoparticles (Au NPs) by photodeposition, were successfully synthesized. The experimental results showed that precise regulation of platinum decorated C₃N₄-Au(C₃N₄-Au/nPt (n is the number of Pt ALD cycles, 1 Å per cycle)) exhibited excellent photocatalytic degradation ability for Rhodamine B (RhB). Under simulated sunlight irradiation, the degradation rate of 10 mg/L RhB(100 mL) by 1.5 mg C₃N₄-Au/10Pt catalysts was 95.8% within 60 min that is much better than other photocatalysts for the degradation of RhB. The efficient degradation mechanism of RhB by C₃N₄-Au/10Pt photocatalysts was studied and the experiments demonstrated the ·O₂^– as main active species played an important role in the photocatalytic process. Local surface plasmon resonance (LSPR) of Au NPs and Schottky barrier between Pt clusters and g-C₃N₄ may be the reasons for enhanced C₃N₄-Au/10Pt photocatalytic performances. Furthermore, the successive catalytic cycles revealed the excellent stability of C₃N₄-Au/10Pt photocatalyst.     

Synthesis of Multifunctional Metal‐ and Metal Oxide Core@Mesoporous Silica Shell Structures by Using a Wet Chemical Approach

We demonstrate a facile wet chemical approach for fabricating spherical metal/metal‐oxide core@mesoporous silica shell hybrid nanoparticles with different core and shell thicknesses. Vertically aligned mesoporous silica (mSiO₂) shells were fabricated over the pre‐synthesized spherical SiO₂ nanoparticles through a three‐step strategy: 1) synthesis of core materials, 2) covering the core with an organic–inorganic composite layer, and 3) removing the organic template through calcinations in air. The mechanisms of hybrid structure formation are proposed. The multifunctional nature of the hybrid structures could be induced by incorporating guest ions/molecules, such as Ag, Mn, and TiO₂, into the pores of an mSiO₂ shell. Mn and TiO₂ cluster‐ incorporated composite structures have been tested to be antioxidizing agents and effective photocatalysts through electron spin resonance, radical scavenging tests, and the photocatalytic degradation of rhodamine B. The possibility of incorporating several hetero‐element guest clusters in these mesoporous composite particles makes them highly attractive for multifunctional applications.     

Development of versatile CdMoO4/g-C3N4 nanocomposite for enhanced photoelectrochemical oxygen evolution reaction and photocatalytic dye degradation applications

Fabrication of an efficient, stable, and versatile photocatalysts for the energy and environment remediation applications is an urgent task for the current researchers. In this work, we have successfully synthesized a versatile hybrid photocatalysts, i.e.; CdMoO₄/g-C₃N₄ (CMO/CN) by a facile and simple one-pot in-situ hydrothermal method. Here CdMoO₄ (CMO) microspheres were deposited on the g-C₃N₄ (CN) sheets. Fabricated CN, CMO, and CMO/CN composite photocatalysts were analyzed with various characterization techniques like UV–visible diffuse reflectance spectra (UV–Vis DRS), photoluminescence spectroscopy (PL), time-resolved fluorescence lifetime (TRFL), electrochemical impedance spectroscopy (EIS), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy–energy-dispersive X-ray analysis (SEM-EDX), transmission electron microscope (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). The results reveal that the formation of a strong heterojunction between two semiconductors leads to the formation of active photocatalyst. Furthermore, as-synthesized materials were tested for the photoelectrocatalytic (PEC) oxygen evolution reactions (OERs) in acidic medium, and photocatalytic (PC) degradation of methylene blue (MB) under light irradiation. Among all tested samples, CMO/CN-10 has shown the highest current density 52.74 mA cm^?2 at 1.95 V with lowest over potential of 0.70 mV on glassy carbon electrode for OER in acidic medium under the light irradiation. The PC degradation rate constant of CMO/CN-10 composite in MB solution is k = 2.0 × 10^?2 min^?1, whereas for the pure CMO and CN degradation rate constant is k = 5.7 × 10^?3 min^?1 and k = 1.2 × 10^?2 min^?1, respectively. This enhancement in PEC and PC properties is due to the fast migration of photo-induced electrons in the case of CMO/CN-10 nanocomposite. Trapping experiment results reveal the major reactive species for PC degradation of MB is ?OH (hydroxyl radicals) and h⁺ (holes), respectively, and suitable PC reaction mechanism also proposed for CMO/CN-10 composites. Based on the above remarkable results, it would be a potential nanocomposite for the PEC oxygen evolution and PC degradation of MB under light illumination.     

0D/1D AgI/MoO3 Z-scheme heterojunction photocatalyst: Highly efficient visible-light-driven photocatalyst for sulfamethoxazole degradation

Low dimension nano photocatalysts show great potential in the field of treating contaminated water for their large surface area and size effect. In this study, a 0D/1D AgI/MoO₃ Z-scheme photocatalyst with striking photocatalytic performance was constructed successfully. The one-dimensional MoO₃ nanobelts were prepared by a simple hydrothermal method, and then it was modified by AgI nanoparticles in a handy deposition approach. When choosing sulfamethoxazole (SMZ) as the target contaminant, the rate constant value of the optimal 0D/1D AgI/MoO₃ composite could hit up to 0.13 min⁻¹, which is nearly 22.4 times and 32.5 times as that of pure MoO₃ (0.0058 min⁻¹) and AgI (0.0040 min⁻¹), respectively. A series of detailed characterizations give evidences that the charge transfer in the composite followed Z scheme mechanism. Therefore, efficient separation/transfer and the remained high redox activity of photogenerated carriers played a vital role in the sharply enhanced photocatalytic properties. The possible degradation pathways of SMZ were proposed based on the intermediates detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Meanwhile, the magnificent cyclic stability makes the material a promising material in the practical application.     

Comparative study of photo- and thermal catalytic hydroxylation of phenol with H2O2over TS-1

The hydroxylation of phenol into catechol (CAT) and hydroquinone (HQ) with hydrogen peroxide and TS-1 catalyst was carried out via both photo- and dark (thermal) reactions. The conversion of phenol and the product ratio of CAT/HQ in the photocatalytic reaction were higher than those in dark (thermal) reaction. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis and characterization of magnetite nanoparticles for photocatalysis of nitrobenzene

The present work shows the photocatalytic degradation of nitrobenzene (NB) using Fe₃O₄ magnetic nanoparticles (MNP) as a photocatalyst in the presence of UV light. The MNP were synthesized by an ultrasonic-assisted reverse co-precipitation (US-RP) method using FeSO₄, FeCl₃ and NH₄OH as precursors. The prepared nanoparticles were characterized by UV–vis spectroscopy, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR), Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Dynamic light scattering (DLS), Zeta potential, Vibrating sample magnetometer (VSM) and Magnetic thermogravimetric analysis (MTGA). The successive decrement in the absorbance at 265 nm shows the effective decrease in NB concentration measured by UV–vis spectroscopy. The reaction intermediates detected by gas chromatography/mass spectrum (GC/MS) were 2-nitrophenol (2-NPh), 3-nitrophenol (3-NPh) and 4-nitrophenol (4-NPh). The prepared MNP showed an optimal NB degradation at an initial pH of 2 and 100 ppm of the photocatalyst.     

多级孔NiMo负载TS-1分子筛催化剂的制备及其加氢脱硫性能

钛硅(TS-1)分子筛的微孔孔道严重限制了其在复杂分子催化转化中的应用,为了克服这一问题,通过酸洗脱、碱刻蚀及二者相结合的方法制备了多级孔TS-1分子筛,并采用等体积共浸渍法制备了相应的NiMo负载型催化剂;使用X射线衍射(XRD)、N₂吸附-脱附、吡啶吸附红外光谱(Py-FTIR)、氢气程序升温还原(H₂-TPR)、X射线光电子能谱(XPS)和高分辨透射电子显微镜(HR-TEM)等方法对多级孔TS-1分子筛的理化性质进行了表征;以二苯并噻吩(DBT)为探针对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,和常规TS-1分子筛相比,多级孔TS-1分子筛保持了MFI拓扑结构,比表面积增大且具有介孔结构,分子筛表面形成了适量的Brønsted酸中心;相应催化剂上活性金属与载体间相互作用得以改善,MoS₂片晶长度和堆垛层数适宜,形成了更多的NiMoS活性相;催化剂活性和选择性均有所提升,尤其是酸洗脱获得的NiMo/AT-TS-1催化剂的活性相较未经处理的NiMo/TS-1催化剂提升了1.2倍,直接脱硫(DDS)路径选择性提升了22%。     

Facile preparation and characterization of anatase TiO2/nanocellulose composite for photocatalytic degradation of methyl orange

Anatase TiO₂/nanocellulose composite was prepared for the first time via a one-step method at a relatively low temperature by using cellulose nanofibers as carrier and tetrabutyl titanate as titanium precursor. The morphology, structure and element composition of the composite were characterized by SEM, EDS, TEM, XRD, XPS and UV–vis DRS. The specific surface area and thermal stability of the composite were investigated by N₂ adsorption–desorption and thermogravimetric analysis, respectively, and the band gaps of the prepared photocatalysts were calculated based on the UV–vis DRS results. In addition, the prepared composite was used for the photocatalytic degradation of methyl orange (aqueous solution, 40 mg L⁻¹). It was found that the composite had a good morphology and anatase crystal structure, and Ti-O-C bond was formed between TiO₂ and nanocellulose. The specific surface area of composite was increased and the thermal stability was decreased compared with the cellulose nanofiber. Moreover, the degradation rate of methyl orange was achieved as 99.72% within 30 min, and no obvious activity loss was observed after five cycles. This work might give some insights into the design of efficient photocatalysts for the treatment of organic dye wastewater.     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载CdMoO₄光催化剂。运用X射线粉末衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱（UV-Vis DRS）和X射线光电子能谱（XPS）等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对CdMoO₄紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与CdMoO₄相比,Ag/CdMoO₄具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O₂^-·和·OH是光催化降解过程的主要活性物种。     

多级孔NiMo负载TS-1分子筛催化剂的制备及其加氢脱硫性能

钛硅(TS-1)分子筛的微孔孔道严重限制了其在复杂分子催化转化中的应用,为了克服这一问题,通过酸洗脱、碱刻蚀及二者相结合的方法制备了多级孔 TS-1 分子筛,并采用等体积共浸渍法制备了相应的 NiMo 负载型催化剂;使用 X 射线衍射(XRD)、N₂吸附-脱附、吡啶吸附红外光谱(Py-FTIR)、氢气程序升温还原(H₂-TPR)、X射线光电子能谱(XPS)和高分辨透射电子显微镜(HR-TEM)等方法对多级孔TS-1分子筛的理化性质进行了表征;以二苯并噻吩(DBT)为探针对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,和常规TS-1分子筛相比,多级孔TS-1分子筛保持了MFI拓扑结构,比表面积增大且具有介孔结构,分子筛表面形成了适量的Brønsted酸中心;相应催化剂上活性金属与载体间相互作用得以改善,MoS₂片晶长度和堆垛层数适宜,形成了更多的 NiMoS活性相;催化剂活性和选择性均有所提升,尤其是酸洗脱获得的 NiMo/AT-TS-1催化剂的活性相较未经处理的NiMo/TS-1催化剂提升了1.2倍,直接脱硫(DDS)路径选择性提升了22%。     

Enhanced photocatalytic degradation of nitrobenzene using MWCNT/β-ZnMoO4 composites under UV light emitting diodes (LEDs)

The β-ZnMoO₄/MWCNT nanocrystal composites were synthesized using hydrothermal method. The physicochemical properties such as structure, morphology and bandgap of synthesized photocatalysts were characterized using PXRD, UV-vis DRS, FTIR, FT-Raman, SEM and TEM analytical methods. PXRD pattern shows the peak shift in the case of synthesized ZnMoO₄/MWCNT which confirms the formation of nanocomposites. Moreover, the strong absorbance in UV region which was evidenced in UV-vis DRS spectra for all the case of synthesized ZnMoO₄ and ZnMoO₄/MWCNT composites. From the SEM and TEM images, the MWCNT was found to have adhered over the ZnMoO₄ nanocrystals. Compared to bare β-ZnMoO₄, β-ZnMoO₄/MWCNT nanocrystal composites exhibited significant higher photocatalytic activity under ultraviolet light emitting diodes (UVLEDs) irradiation for the degradation of nitrobenzene (NB; 2.606 × 10^?4 M). This may be due to the effective charge transfer in the composite and optimized electron hole pair recombination. The photocatalytic activity of the synthesized photocatalysts was also studied under visible LEDs and it is observed that the photocatalytic degradation of NB was 97%, 77%, 65% and 52% under the irradiation of UV, blue, green, and red LEDs respectively.     

Highly Efficient Photocatalytic Remediation of Simulated Polycyclic Aromatic Hydrocarbons (PAHs) Contaminated Wastewater under Visible Light Irradiation by Graphene Oxide Enwrapped Ag3PO4 Composite.

Effective removal of polycyclic aromatic hydrocarbons (PAHs) from wastewater before their discharge into the environment is an ever pressing requirement. In this study, for the first time, simulated PAHs contaminated wastewater was photocatalytically remediated with graphene oxide (GO) enwrapped silver phosphate as visible light‐driven photocatalysts. The GO/Ag₃PO₄ photocatalysts exhibited superior photocatalytic activity and stability compared with pure Ag₃PO₄, g‐C₃N₄ and TiO₂ (P25). The degradation efficiency of naphthalene, phenanthrene and pyrene could reach 49.7%, 100.0% and 77.9%, rspectively within 5 min irradiation. The apparent rate constants of photocatalytic degradation of 3 wt% GO/Ag₃PO₄ composite photocatalyst were 0.14, 1.21 and 2.46 min⁻¹ for naphthalene, phenanthrene and pyrene, respectively. They were about 1.8, 1.5 and 2.0 times higher than that of pure Ag₃PO₄, and much higher than that of g‐C₃N₄ and TiO₂. Meanwhile, the efficiencies of 44.6%, 95.2% and 83.8% were achieved for naphthalene, phenanthrene and pyrene degradation even after 5 times of recycling in the GO/Ag₃PO₄‐PAHs photocatalysis system. Reactive species of ∙O₂⁻ and h⁺ were considered as the main participants for oxidizing naphthalene, phenanthrene and pyrene.     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载Cd Mo O4光催化剂。运用X射线粉末衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱(UV-Vis DRS)和X射线光电子能谱(XPS)等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对Cd Mo O4紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与Cd Mo O4相比,Ag/Cd Mo O4具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O2-·和·OH是光催化降解过程的主要活性物种。     

Effective synthesis of nanoscale anatase TiO2 single crystals using activated carbon template to enhance the photodegradation of crystal violet

Nanoscale anatase TiO₂ single crystals were successfully synthesized using three kinds of activated carbon (AC) templates through a simple sol–gel method. The optimal photocatalyst (T‐WOAC) was obtained using wood‐based AC template. X‐ray diffraction, transmission electron microscopy and Brunauer–Emmett–Teller analyses revealed that T‐WOAC possessed a small crystallite size of 8.7 nm and a clear mesoporous structure. The photocatalytic properties of samples were then evaluated through photodegradation of crystal violet (CV). Results implied that the photocatalysts prepared using the AC templates exhibited superior photocatalytic activity to that of the original TiO₂. This enhancement may be due to the small crystallite size, large specific surface area and pore volume of the catalysts prepared with ACs. T‐WOAC showed high photocatalytic activity, CV degradation of 99.01% after 120 min of irradiation and k = 0.03914 min^?1, which is 3.9 times higher than that of the original TiO₂ (k = 0.00994 min^?1). This result can be mainly attributed to the application of WOAC with moderate specific surface area and pore volume to produce T‐WOAC. Alkaline conditions benefitted the photodegradation of CV over photocatalysts. This work proposes a possible degradation mechanism of CV and indicates that the fabricated photocatalysts can be used to effectively remove CV from aqueous solutions.     

Photocatalytic efficiency of nanocrystalline zeolite TS-1 for the degradation of methyl orange

The photocatalytic properties of nanocrystalline TS-1 were confirmed via the degradation of an aqueous solution of the model compound methyl orange (MO). The light intensity and quantum yield were measured by ferrioxalate actinometry and the values are 1.7 × 10⁻⁵ einstein l⁻¹ s⁻¹ and 0.71, respectively. The experimental parameters such as catalyst loading, pH and initial concentration of MO were optimized at 1.5 g/L, 10 and 300 μM, in order. The results showed that the dye molecules are completely degraded to CO₂, H₂O and simple inorganic ions.     

Synthesis of V5+‐doped Ag/AgCl photocatalysts with enhanced visible light photocatalytic activity

V⁵⁺‐doped Ag/AgCl photocatalysts were prepared via the ion exchange method. The catalysts were characterized using X‐ray diffractometry, transmission electron microscopy, and energy‐dispersive X‐ray, X‐ray photoelectron, Fourier transform infrared and ultraviolet–visible spectroscopies. The V⁵⁺‐doped Ag/AgCl photocatalysts show much higher photocatalytic activities than Ag/AgCl under visible light irradiation for methyl orange (MO) decomposition. Especially, the 2.0 wt% V⁵⁺‐doped Ag/AgCl photocatalyst shows the highest photocatalytic activity and also high stability after five cycles. The MO degradation rate during each cycle is almost maintained at 97%. Electron spin resonance spectroscopy and radical trapping experiments reveal that holes play an important role in the photocatalytic process.     

Rh(OH)x/TS-1@KCC-1双功能催化剂上一锅反应合成伯酰胺

在微乳液体系中成功地将花瓣状介孔氧化硅微球(KCC-1)包覆在钛硅分子筛TS-1表面, 得到了一种新型微孔/介孔复合核壳结构材料TS-1@KCC-1. 详细考察了TS-1@KCC-1的合成条件及可能的形成机理. 适宜的合成温度及时间分别为373-393 K和4 h. 壳层厚度可方便地通过改变硅源正硅酸乙酯和TS-1的比例在25-80 nmm间进行调控. 以TS-1@KCC-1为载体负载Rh(OH)_x后即得到双功能催化材料Rh(OH)_x/TS-1@KCC-1, 该材料同时具有Ti和Rh(OH)_x活性中心, 可以高效催化醛、氨水和过氧化氢经一锅串联反应直接制备得到伯酰胺.     

Effect of Cl− anions on photocatalytic decomposition of gaseous ozone over Au @ Ag/TiO2 catalyst

Au core Ag shell composite structure nanoparticles were prepared using a sol method. The Au core Ag shell composite nanoparticles were loaded on TiO₂ nanoparticles as support using a modified powder–sol method, enabling the generation of Au @ Ag/TiO₂ photocatalysts for photocatalytic decomposition and elimination of ozone. The sols were characterized by means of ultraviolet–visible light (UV–Vis) reflection spectrometry, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The activity of the Au @ Ag/TiO₂ photocatalysts for photocatalytic decomposition and elimination of ozone was evaluated and the effect of Cl^? anions on the photocatalytic activity of the catalysts was highlighted. Results showed that Au @ Ag/TiO₂ prepared via the modified powder–sol route in the presence of an appropriate amount of NaCl solid as demulsifier had better activity in the photocatalytic decomposition and elimination of ozone. At the same time, Au @ Ag/TiO₂ catalysts had better ability to resist poisonous Cl^? anions than conventional Au/TiO₂ catalyst. The reasons could be, first, that NaCl was capable of reducing the concentration of free Ag⁺ by adsorption on the surface of Ag particles forming AgCl and enhancing the formation of Au core Ag shell particles, leading to a better resistance to Cl^? anions of the catalysts, and, second, AgCl took part in the photocatalytic decomposition of ozone together with Au @ Ag/TiO₂ catalysts and had a synergistic effect on the latter, resulting in better photocatalytic activity of Au @ Ag/TiO₂ catalysts.