Synthesis of AgCl/Ti_(3)C_(2)@TiO_(2)Ternary Composite Photocatalysts for Photocatalytic Oxidation of 1,4-Dihydropyridine and Tetracycline Hydrochloride

AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.

Photodecomposition of H_2S to H_2 over Cd_xZn_(1-x)S composite photocatalysts

A series of CdxZn1-xS (x = 0.1-0.9) photocatalysts were prepared by coprecipitation. They could form solid solution semiconductors with hexagonal phase in agreement with pure CdS by characterization of XRD. The photophysical properties of CdxZn1-xS photocatalysts were measured by UV-Vis diffuse reflectance spectrum and surface photovoltage spectroscopy (SPS). The band gap energy gradually reduced with the increasing of x value in CdxZn1-xS,and when x = 0.7,the Cd0.7Zn0.3S photocatalyst had the strongest surface photovoltage. CdxZn1-xS photocatalysts were used in the photodecomposition of H2S to H2. The evolution rate of H2 over the Cd0.7Zn0.3S photocatalyst was also the highest among CdxZn1-xS photocatalysts. And the effect of calcination temperature on the evolution rate of H2 was investigated and the optimum temperature was 650°C.

Heterojunction： important strategy for constructing composite photocatalysts

As an ideal solution to energy and environment issues,conversion of sunlight into solar fuels by photocatalytic water splitting and greenhouse gas(CO_2)reduction has attracted keen research interest of multi-field scientists.In the past four decades,a large number of semiconductor photocatalysts have been

Carbon nanotubes/TiO_2 nanotubes composite photocatalysts for efficient degradation of methyl orange dye

A series of carbon nanotubes/TiO2 nanotubes （CNTs/TNTs） composite photocatalysts were successfully prepared by incorporation of CNTs in HNO3 washing process. These photocatalysts were characterized by XRD, N2 physical adsorption, UV-vis diffuse reflectance spectroscopy, TEM and Raman spectroscopy, respectively, and their photocatalytic activities were tested by using methyl orange （MO） as a model compound. Also, the effects of amount of CNTs incorporated, calcination temperature and amount of catalyst on the photocatalytic activity of the composite photocatalyst were systematically investigated. The results show that the CNTs/TNTs composite exhibits much higher photocatalytic activity than that of the TNTs or CNTs alone.

Recycling Spent LiCoO_(2)Battery as a High-efficient Lithiumdoped Graphitic Carbon Nitride/Co_(3)O_(4)Composite Photocatalyst and Its Synergistic Photocatalytic Mechanism

The ever-increasing quantity of spent lithium-ion batteries(LIBs)is both a potential environmental pollutant and a valuable resource.The spent LIBs recycling mainly aimed at the separation of valuable elements.Some issues still exist in these processes such as high energy consumption and complex separation procedures.This study avoided element separation and proposed a facile approach to transform spent LiCoO_(2) electrode into a lithium(Li)-doped graphitic carbon nitride(g-C_(3)N_(4))/Co_(3)O_(4) composite photocatalyst through one-pot in situ thermal reduction.During the thermal process,melamine served as the reductant for LiCoO_(2) decomposition and the raw material for g-C_(3)N_(4) production.Li was in situ doped in g-C_(3)N_(4) and the generated Co_(3)O_(4) was in situ integrated,forming a Li-doped g-C_(3)N_(4)/Co_(3)O_(4) composite photocatalyst.This special composite exhibited an enhanced photocatalytic performance,and its photocatalytic H2 production and RhB degradation rates were 8.7 and 6.8 times higher than those of g-C_(3)N_(4).The experiments combined with DFT calculation revealed that such enhanced photocatalytic efficiency was ascribed to the synergy effect of Li doping and Co_(3)O_(4) integrating,which extended the visible light absorption(450-900 nm)and facilitated the charge transfer and separation.This study transforms waste into a high-efficient catalyst,realizing high-valued utilization of waste and environmental protection.

Photocatalytic remediation ofγ-hexachlorocyclohexane contaminated soils using TiO_2 and montmorillonite composite photocatalyst

TiO2 and montmorillonite composite photocatalysts were prepared and applied in degrading γ-hexachlorocyclohexane （γ-HCH） in soils. After being spiked with γ-HCH, soil samples loaded with the composite photocatalysts were exposed to UV-light irradiation. The results indicated that the photocatalytic activities of the composite photocatalysts varied with the content of TiO2 in the order of 10%〈70%〈50% 〈30%, Moreover, the photocatalytic activity of the composite photocatalysts with TiO2 content 30% was higher than that of the pure P25 with the same mass of TiO2. The strong adsorption capacity of the composite photocatalysts and quantum size effect may contribute to its increased photocatalytic activities. In addition, effect of dosage of composite photocatalysts and soil pH on γ-HCH photodegradation was investigated. Pentachlorocyclohexene, trichlorocyclohexene, and dichlorobenzene were detected as photodegradation intermediates, which were gradually degraded with the photodegradation evolution.

TiO_2/polyaniline composites:An efficient photocatalyst for the degradation of methylene blue under natural light

Polyaniline （PAn） sensitized nanocrystalline TiO2 composites （TiO2/PAn） were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue （MB）. The results showed that PAn was able to sensitize TiO2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light （λ： 190 ～ 800 nm）, whereas pure TiO2 absorbed ultraviolet light only （λ 〈 380 nm）. Under the irradiation of natural light, MB could be degraded more efficiently on the TiO2/PAn composites than on the TiO2 Furthermore, it could be easily separated from the solution by simple sedimentation.

Preparation and characterization of Fe_(2)O_(3)/Bi_(2)WO_(6)composite and photocatalytic degradation mechanism of microcystin-LR

The long-standing popularity of semiconductor photocatalysis,due to its great potential in a variety of applications,has resulted in the creation of numerous semiconductor photocatalysts,and it stimulated the development of various characterization methods.In this study,Fe_(2)O_(3)/Bi_(2)WO_(6)composite with a flower-like microsphere and hierarchical structure was synthesized with the facile hydrothermal-impregnation method without any surfactants.X-ray diffraction(XRD),scanning electron microscopy(SEM),ultravioletevisible(UV-Vis)diffuse reflectance spectroscopy,and photoluminescence spectroscopy were used to characterize the structures of the samples.The specific surface area was estimated with the Brunauer-Emmett-Teller(BET)method,and pore size distribution was determined using the Barrett-Joyner-Halenda(BJH)method.The synthesized Fe_(2)O_(3)/Bi_(2)WO_(6)composite had an average diameter of approximately 4 nm,with smaller specific surface area and larger pore diameter than those of pristine Bi_(2)WO_(6).The results of XRD and SEM analyses confirmed that the composite was composed of Fe_(2)O_(3)and Bi_(2)WO_(6).The absorption edge of Bi_(2)WO_(6)was at a wavelength of 460 nm.By contrast,the absorption edge of Fe_(2)O_(3)/Bi_(2)WO_(6)to visible light was redshifted to 520 nm,with narrower bandgap width and stronger visible light response.It was also found that the main active substances in the degradation of microcystin-LR(MC-LR)were hydroxyl radicals(·OH)and electron holes(h^(+)).Consequently,the results further showed that the heterojunction between Fe_(2)O_(3)and Bi_(2)WO_(6)can improve the charge transfer rate and effectively separate the photoinduced electrons and holes.Compared with Bi_(2)WO_(6),Fe_(2)O_(3)/Bi_(2)WO_(6)had no significant difference in the adsorption capacity of MC-LR and had more efficient photocatalytic degradation activity of MC-LR.The degradation rates of MC-LR by Fe_(2)O_(3)/Bi_(2)WO_(6)and Bi_(2)WO_(6)reached 80%and 56%,respectively.The degradation efficiency of MC-LR was affected by the initial pH value,initial Fe_(2)O_(3)/Bi_(2)WO_(6)concentration,and initial MC-LR concentration.

Fabrication of Bi_2O_3/TiO_2nanocomposites and their applications to the degradation of pollutants in air and water under visible-light

A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light （λ≥ 420 nm） was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.

ZnFe2O4 deposited on BiOCl with exposed （001） and （010） facets for photocatalytic reduction of C02 in cyclohexanol

ZnFe2O4-BiOC1 composites were prepared by both hydrothermal and direct precipitation processes and the structures and properties of the samples were characterized by various instrumental techniques. The samples were then used as catalysts for the photocatalytic reduction of CQ in cyclohexanol under ultraviolet irradiation to give cyclohexanone （CH） and cyclohexyl formate （CF）. The photocatalytic CO2 reduction activities over the hydrothermally prepared ZnFeaO4-BiOCl composites were higher than those over the directly-precipitated composites. This is because compared to the direct-precipitation sample, the ZnFe2O4 nanoparticles in the hydrothermal sample were smaller and more uniformly distributed on the surface of BiOCl and so more heterojunctions were formed. Higher CF and CH yields were obtained for the pure BiOCl and BiOCl composite samples with more exposed （001） facets than for the samples with more exposed （010） facets. This is due to the higher density of oxygen atoms in the exposed （001） facets, which creates more oxygen vacancies, and thereby improves the separation efficiency of the electron-hole pairs. More importantly, irradiation of the （001） facets with ultraviolet light produces photo-generated electrons which is helpful for the reduction of CO2 to -CO2^-. The mechanism for the photocatalytic reduction of CO2 in cyclohexanol over ZnFe204-BiOCl composites with exposed （001） facets involves electron transfer and carbon radical formation.