A heterojunction thin film consisting of n-type titanium dioxide (TiO2) and p-type cuprous oxide (Cu2O) was fabricated on an FTO conducting glass. The TiO2 films were grown on the FTO glass by sol–gel and spray pyrolysis methods, and Cu2O was deposited on it via the hydrothermal method. The morphology, crystalline structure, and optical absorption characteristics were studied by scanning electron microscopy, X-ray diffraction, and ultraviolet–visible diffuse reflectance spectrum, respectively. The results show that the surface of the Cu2O/TiO2 film was composed of net and large grains, which contributed to a large specific surface area. The crystal phase of the TiO2 in the Cu2O/TiO2 film remained anatase. The crystal phase of the Cu2O could not be detected as it is found in traces. The Cu2O/TiO2 film had a stronger optical absorption ability than the pure TiO2 film. To investigate catalytic activity, a photocatalytic degradation experiment of the Cu2O/TiO2 film was performed in a homemade thin-layer micro-reactor. The photocatalytic degradation of methylene blue increased with increasing amounts of deposited Cu2O until a maximum limit was reached. The photocatalytic activity might have declined with an increase in Cu2O content. The metallic oxide has the potential to screen other photocatalysts from the UV source. 相似文献
The structural properties of Au/TiO2 catalyst were studied by X-ray diffraction, UV-visible diffuse reflectance, photoluminescene, scanning transmission and electron
microscope, and temperature programmed reduction. The photocatalytic activity of the catalysts was evaluated for the degradation
of various azo-dyes such as methylene blue, methyl orange, reactive blue-4, and eosin-B under solar irradiation. It was found
that TiO2 catalyst modified with gold exhibits higher percentage of degradation compared to starting TiO2. For example, TiO2 showed 35% of methyl orange degradation whereas gold modified TiO2 possessed 82%. Effect of different parameters such as pH and dye concentration has been evaluated and the photocatalytic
activity was correlated with physico-chemical properties. The dye degradation rate followed first order kinetics. 相似文献
Cuprous oxide (Cu2O) nanoparticles and microcubes have been successfully fabricated by reduce of CuSO4 using ascorbic acid at room temperature. The as-synthesized products were easily separation and purification, because there were no template or surfactant has been introduced. All of the samples were characterized by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FTIR) and ultraviolet and visible light spectrometer (UV–vis). The microscale Cu2O samples exhibited a high catalytic activity on photodegradation of methyl orange by visible light. It was found that Cu2O microcubes have higher photocatalytic activity and the photocatalytic degradation ratio of methyl orange reached to 98.1%. 相似文献
A series of modified porous activated carbon (AC) catalysts prepared by impregnation were investigated for the low-temperature (≤250°C) selective catalytic reduction (SCR) of NOx with NH3 with simultaneous removal of SO2. The effects of various preparation conditions and reaction conditions on NO and SO2 conversions were observed, such as support type, active components, copper loading, calcination temperature and presence of H2O and O2. The modified AC catalysts were characterized by BET, XRD, TG and TPX methods. The activity test results showed that the optimal catalyst is 15% Cu/WCSAC which can provide 52% NO conversion and 68% SO2 conversion simultaneously at 175°C with a space velocity of 30000 h?1, and the optimal calcination temperature was 500°C. The presence of H2O could inhibit NO conversion and promote the SO2 conversion. The effect of O2 (0–5%) was evaluated, and the NO and SO2 conversions were best when the concentration of O2 was 3%. Research demonstrated that Cu/WCSAC catalyst was a kind of potential catalysts due to the amorphous phase, high specific areas and high active ability. 相似文献
As p–n heterojunction photocatalysts usually possess dramatically improved photocatalytic activity than single photocatalysts, a novel ZnO/Cu2O heterojunction was designed by a facile self-templating method in this study. The crystal structure, chemical composition, surface morphology, and optical property of ZnO/Cu2O heterojunction were investigated to clarify the structure-property correlation. Scanning electron microscope and transmission electron microscope images proved the uniform core-shell submicrospheres of ZnO/Cu2O, in which a three-dimensional flower-like ZnO core was coated by a shell comprised of Cu2O nanoparticles. The photoresponse result showed that the band gap of the ZnO/Cu2O core-shell submicrospheres became narrow, and the absorption edge shifted from the ultraviolet region (380?nm) to the visible region (500?nm) compared with the pure ZnO microflowers. For the degradation of Rhodamine B under visible light, the photocatalytic efficiency of ZnO/Cu2O submicrospheres reached 96% within 40?min of reaction time, which was 3.8 times higher than that of pure ZnO microflowers and up to 4.5 times than that for pure Cu2O nanoparticles. The remarkable visible light-driven photocatalytic performance is mainly attributed to the extended photoresponse range and effective separation of the photo-generated electron-hole pairs in the unique heterojunction.
The Cu/ZSM-5 catalysts prepared by different copper precursors were used for the selective catalytic reduction (SCR) of NOx with NH3. The Cu/ZSM-5 catalyst prepared by the copper nitrate (Cu/ZSM-5-N) presented the best performance among the Cu/ZSM-5 catalysts and showed above 90 % NOx conversion at 225–405 °C. The average particle size of CuO was 5.82, 9.20, and 11.01 nm over Cu/ZSM-5-N, Cu/ZSM-5-S (prepared by copper sulfate), and Cu/ZSM-5-C (prepared by copper chloride), respectively. The Cu/ZSM-5-N catalyst showed the highly dispersed copper species, the strong surface acidity, and the excellent redox ability compared with the Cu/ZSM-5-C and Cu/ZSM-5-S catalysts. The Cu+ and Cu2+ existed in the Cu/ZSM-5 catalysts and the abundant Cu+ over Cu/ZSM-5-N might be responsible for the superior SCR activity. 相似文献
B-doped TiO2 nanotubes (B/TiO2 NTs) were prepared by the combination of sol–gel process with hydrothermal treatment. The prepared catalysts were characterized
by XRD, TEM and XPS. The photocatalytic activity of B/TiO2 NTs was evaluated through the photodegradation of aqueous methyl orange. The results demonstrated that the 1.5% B/TiO2 NTs calcined at 300 °C possessed the best photocatalytic activity. Compared with pure TiO2 nanotubes, the doping with B significantly enhanced the photocatalytic efficiency. 相似文献
A series of MoO3 doped Fe2O3 catalysts prepared by the co-precipitation method were investigated in the selective catalytic reduction of NO by NH3 (NH3-SCR). The catalysts displayed excellent catalytic activity from 225 to 400°C and high tolerance to SO2/H2O poisoning at 300°C. To characterize the catalysts the N2-BET, XRD, Raman, NO-TPD, NH3-TPD and in situ DRIFTS were carried out. It was found that the main reason explaining a high NH3-SCR performance might be the synergistic effect between Fe and Mo species in the catalyst that could enhance the dispersion of Fe2O3 and increase NH3 adsorption on the catalyst surface. 相似文献
Zeolite-based photocatalysts were prepared by the sol-gel and deposition methods. The photocatalysts were characterised by
X-ray diffraction, nitrogen adsorption-desorption isotherms, FTIR spectroscopy, scanning electron microscopy and energy-dispersive
X-ray spectrometry. The activity of the prepared photocatalysts was evaluated by the UV-induced degradation of acid blue 92,
a textile dye in common use. The effect of various parameters, such as catalyst concentration, initial dye concentration,
thiosulphate concentration and pH, on the rate and efficiency of the photocatalytic degradation of acid blue 92 was investigated.
The results showed that each parameter influenced the degradation rate and efficiency in a particular way. It was also found
that, under optimised conditions, Ag/AgBr/TiO2/zeolite exhibited the highest photocatalytic performance. A comparison of catalytic activity when exposed to visible light
under the same conditions showed that the photocatalysts containing AgBr had the highest activity. 相似文献
Iron oxide-loaded Cu2O photocatalysts were prepared by a facile hydrothermal method. The binary mixed metal oxide photocatalyst was characterized by XRD, FE-SEM, FTIR, UV–Vis-DRS, particle size and zeta potential measurements. XRD analysis showed that Fe2O3/Cu2O catalysts were phase pure and highly crystalline in nature. FE-SEM images revealed the formation of nanospherical Fe2O3 over the Cu2O surface during hydrothermal reaction. From UV–Vis diffuse reflectance spectroscopy studies, the optical band gap of the Fe2O3/Cu2O photocatalyst was found to be slightly red-shifted to 1.85 eV, after loading of Fe2O3. The zeta potential analysis revealed that the surface of the Fe2O3/Cu2O photocatalyst was negatively charged in neutral solution. The loading of n-type Fe2O3 on p-type Cu2O augments the charge carrier separation at the interface, which was evident from the enhanced photodegradation of organic pollutants (Methylene blue and Rhodamine B dyes) under visible light irradiation. 相似文献
The comparative study of the role of binary oxide support on catalyst physico-chemical properties and performance in methanol
synthesis were undertaken and the spinel like type structures (ZnAl2O4, FeAlO3, CrAl3O6) were prepared and used as the supports for 5% metal (Cu, Ag, Au, Ru) dispersed catalysts. The monometallic 5% Cu/support
and bimetallic 1% Au (or 1% Ru)-5% Cu/support (Al2O3, ZnAl2O4, FeAlO3, CrAl3O6) catalysts were investigated by BET, XRD and TPR methods. Activity tests in methanol synthesis of CO and CO2 mixture hydrogenation were carried out. The order of Cu/support catalysts activity in methanol synthesis: CrAl3O{ia6} > FeAlO3 > ZnAl2O4 is conditioned by their reducibility in hydrogen at low temperature. Gold appeared more efficient than ruthenium in promotion
of Cu/support catalysts.
Published in Russian in Kinetika i Kataliz, 2009, Vol. 50, No. 2, pp. 242–248.
The article is published in the original. 相似文献
Magnetically separable Fe3O4/AgCl photocatalysts were prepared by a one-pot sequential method. A series of techniques proved the hybrid structure of Fe3O4/AgCl composites. Fe3O4/AgCl composites had a much higher photocatalytic activity toward Rhodamine B (RhB) degradation than pure AgCl under the simulated solar light irradiation. The existence of metal Ag resulted in high photocatalytic activity of Fe3O4/AgCl, which was related with the amount of metallic Ag. The scavenging experiments showed that the degradation reaction most probably was initiated by the photoinduced single-electron transfer, and the generation of superoxide anion (O2-·) played a significant role. The composite photocatalysts could be recycled by applying an external magnetic field, and the reused composites maintained their original photocatalytic activity. Fe3O4/AgCl composites were highly efficient, magnetically separable, and recoverable. This proves their potential applications in the photodegradation of organic pollutants. 相似文献
Gold catalysts with loadings ranging from 0.5 to 7.0 wt% on a ZnO/Al2O3 support were prepared by the deposition–precipitation method (Au/ZnO/Al2O3) with ammonium bicarbonate as the precipitation agent and were evaluated for performance in CO oxidation. These catalysts
were characterized by inductively coupled plasma-atom emission spectrometry, temperature programmed reduction, and scanning
transmission electron microscopy. The catalytic activity for CO oxidation was measured using a flow reactor under atmospheric
pressure. Catalytic activity was found to be strongly dependent on the reduction property of oxygen adsorbed on the gold surface,
which related to gold particle size. Higher catalytic activity was found when the gold particles had an average diameter of
3–5 nm; in this range, gold catalysts were more active than the Pt/ZnO/Al2O3 catalyst in CO oxidation. Au/ZnO/Al2O3 catalyst with small amount of ZnO is more active than Au/Al2O3 catalyst due to higher dispersion of gold particles. 相似文献
The effect of the microstructure of titanium dioxide on the structure, thermal stability, and catalytic properties of supported CuO/TiO2 and CuO/(CeO2-TiO2) catalysts in CO oxidation was studied. The formation of a nanocrystalline structure was found in the CuO/TiO2 catalysts calcined at 500°C. This nanocrystalline structure consisted of aggregated fine anatase particles about 10 nm in size and interblock boundaries between them, in which Cu2+ ions were stabilized. Heat treatment of this catalyst at 700°C led to a change in its microstructure with the formation of fine CuO particles 2.5–3 nm in size, which were strongly bound to the surface of TiO2 (anatase) with a regular well-ordered crystal structure. In the CuO/(CeO2-TiO2) catalysts, the nanocrystalline structure of anatase was thermally more stable than in the CuO/TiO2 catalyst, and it persisted up to 700°C. The study of the catalytic properties of the resulting catalysts showed that the CuO/(CeO2-TiO2) catalysts with the nanocrystalline structure of anatase were characterized by the high-est activity in CO oxidation to CO2. 相似文献
Fluorine-modified TiO2 nan oparticles were synthesized by introducing TiF4 as a fluorine source either before or after the sufficient hydrolysis and condensation of Ti(OEt)4. The photocatalytic activity of the fluorine-modified catalysts was found to be greatly affected by the fluorine position
in TiO2 nanoparticles. When TiF4 and Ti(OEt)4 hydrolyzed with synchronization, the fluorine tended to be doped in the lattice. The formation of Ti3+ defects could result in charge recombination in bulk and bring down the photocatalytic activity. In contrast, if TiF4 was introduced after the sufficient hydrolysis and condensation of Ti(OEt)4. Ti−F bonds could exist mainly on the TiO2 particles surface, which not only prevented the growth of anatase crystals but also facilitated the transfer of organic compounds
from solution to catalyst surface by reducing the hydrophilic properties. 相似文献
In this work, TiO2 and doped TiO2 photocatalysts (Fe/TiO2 and Cu/TiO2) were synthesized by the sol–gel method. The main objective of this study was to investigate the influence of dopants on the structure, morphology, and activity of the catalysts in powder and immobilized states. XRF, XRD, and SEM methods were used to characterize the catalysts. The structure and phase distribution of the nanocrystalline powders were identified by XRD. Nanoparticles crystallite size and the degree of crystallinity were affected by doping. The anatase contents of catalysts were achieved as follows: TiO2 (5.89 %) < Fe/TiO2 (42.17 %) < Cu/TiO2 (70.28 %). It was indicated that the activity of the catalysts strongly depends on the anatase content. Under the same circumstances, copper-modified TiO2 exhibited a twofold higher photocatalytic activity compared with TiO2. The nanostructured catalysts were immobilized on light expanded clay aggregate (LECA) granules in order to investigate the effect of a novel support on the activity of the catalysts. Morphological changes are recognizable in the SEM images. Activity tests indicated that the best catalytic performance was assigned to Cu/TiO2/LECA. After 120 min of irradiation, 61 % degradation of phenol in synthetic wastewater was achieved. The high photocatalytic activity of Cu/TiO2/LECA confirms that LECA is as an excellent support. 相似文献
A novel fabrication of Cu2O nanoparticles was successfully achieved through the reduction of Cu2+ in the interlayer of montmorillonite (denoted as MT). The Cu2O nanoparticles formed in the clay interlayer (denoted as Cu2O/MT) had a lamellate shape of 20–100 nm in width and ca. 0.39 nm in thickness, and thus, the Cu2O/MT exhibited a higher specific surface area than neat Cu2O. The Cu2O/MT was applied to a photocatalyst, and its photocatalytic activity was examined in terms of water reduction (i.e., H2 evolution) in the presence of methanol (electron donor). The Cu2O/MT showed a high photocatalytic activity in comparison with neat Cu2O; moreover, the photocatalytic activity was improved by loading a Pt catalyst onto the surface of Cu2O. Based on the dependencies of photocatalytic activity on light intensity as well as methanol concentration, it was revealed that the H2 evolution from water on Cu2O/MT is the rate-determining step. Thus, the active and efficient photocatalysis of Cu2O/MT was associated with an increase in specific surface area corresponding to the number of active sites. 相似文献