Photocatalytic Performance Of Cu Research Articles

Boosting the photocatalytic performance of Cu2O for hydrogen generation by Au nanostructures and rGO nanosheets.

As a narrow band-gap semiconductor, cuprous oxide (Cu2O) has a relatively high conduction band that can exhibit high driving force for the photocatalytic generation of hydrogen under visible light. Besides, its adjustable morphologies and abundant source also make it possible to be employed as a theoretically optimal photocatalyst. However, the low charge migration and poor stability commonly limit its practical application, and various strategies have been explored in previous studies. In this study, we have novelly utilized Au nanorod (NR) and nanobipyramid (NBP) nanocrystallites as well as rGO nanosheets to boost the photocatalytic activity of Cu2O over hydrogen generation. The ternary rGO wrapped Au@Cu2O with a yolk-shelled structure (y-Au@Cu2O/rGO) was synthesized by a handy and controllable method. When excited by solar light (λ > 400 nm), it was found that the H2 yields of Cu2O/rGO, y-Au nanoparticle@Cu2O/rGO, y-Au NR@Cu2O/rGO, and y-Au NBP@Cu2O/rGO were increased in the order of 248, 702, 1582 and 1894 μmol g-1 in 4 h. The outstanding photocatalytic performances of y-Au NR@Cu2O/rGO and y-Au NBP@Cu2O/rGO could be attributed to the combination function of quick electron transfer of rGO and abundant near-infrared-light-driven hot carriers on Au NRs and NBPs that could inject into Cu2O and then a quick transfer to rGO to participate in H2 reduction. Besides the above results, it was also found that Cu2O maintained good stability after several cycling photocatalysis tests, which could be ascribed to the migration of holes from Cu2O to Au that prevented the photooxidation of Cu2O. This study may give a guide to fabricating controllable and effective photocatalysts based on plasmonic metals, semiconductors, or two-dimensional nanosheets, which possess full-solar-light-driven photocatalytic activities in the future.

Facile fabrication of AgFe1−xCuxO2 composite with abundant oxygen vacancies for boosted photocatalytic Cr (VI) reduction and organic pollutants degradation under visible light

In order to enhance the utilization of visible light and improve photocatalytic performance of AgFeO2, in this work, a novel copper (Cu) doped AgFeO2 composite catalysts with abundant oxygen vacancies (OVs) were synthesized by the co-precipitation method. The results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) showed Cu was successfully doped in AgFeO2 to form lattice defects, resulting in a large number of oxygen vacancies, which is beneficial for oxygen molecules to be activated into superoxide radicals. Compared with pure AgFeO2, the Cu doped samples expand the absorption region of visible light, thereby enhancing photocatalytic activity in the oxidization of organic pollutants and the reduction of Cr (VI). In a mixed Cr (VI)/ Acid Red G (ARG) solution, the 20 mg/L of ARG could be almost completely degraded within 90 min by Cu doped AgFeO2 composite, while the reduction efficiency of Cr (VI) is up to 90.19%, which is 1.95 times higher than that of AgFeO2. After the fourth photocatalytic recycling experiment, the photocatalytic performance of Cu doped AgFeO2 composite is still superior. The results of scavenger experiments show that holes (h+) and superoxide anions (O2•-) were the main dominant reactive for promoting photocatalytic reduction of Cr (VI) and degradation of organic pollutants over the Cu doped AgFeO2 composites. Based on the results of photoluminescence spectra (PL) and electron spin resonance (ESR), the enhanced photocatalytic performance of the Cu doped AgFeO2 could be contributed to oxygen vacancy caused by doping defects and the enhancement of visible light absorption.

Cu–CuO and Cu–CuO–ZnO hybrid nanostructures as photocatalysts and catalysts for efficient removal of pollutants

Cu–CuO and Cu–CuO–ZnO hybrid nanostructures were fabricated by wet chemical route. The structural and morphological properties of the synthesized nanomaterials were well characterized by Raman spectroscopy, X-ray diffraction, field emission scanning electron microscopy while their optical and photocatalytic parameters were studied by using UV–Vis absorption spectroscopy. The photocatalytic performance of Cu–CuO–ZnO hybrid nanostructures and Cu–CuO hybrid nanostructures were examined via photocatalytic decomposition of methylene blue and methyl orange dyes in water whereas catalytic properties of the synthesized hybrid nanostructures were examined through reductive transformation of 4-nitrophenol (4-NP) in water. The prepared nanostructures of Cu–CuO–ZnO completely decomposed methylene blue (MB) and methyl orange (MO) in 54 and 45 min, respectively while catalytic decay of 4-NP was achieved in just 2 min using Cu–CuO nanohybrids. The developed Cu–CuO and Cu–CuO–ZnO hybrid nanostructures are extremely capable for the practical and innovative photocatalytic decomposition of waste at large scale as well as catalytic reduction of toxic chemicals from wastewater.

Photocatalytic water splitting properties of Cu2+ exchanged Beta zeolites

Photocatalytic water splitting with solar energy is the most promising and environmentally friendly hydrogen production method. Having an efficient and cost-effective photocatalyst is key to hydrogen production. Cu dopant has been shown to greatly enhance photocatalytic activities. In this work, Cu2+ ions were doped into Beta zeolite powders (Cu–Beta) by the ion exchange method. The hydrogen evolution efficiency of Cu–Beta was much higher than the raw Beta zeolites without Cu loading. After solid phase reaction, the band gap of Cu–Beta reduced from 3.48 eV to less than 2 eV, and as a result enhanced the optical absorption intensity, particularly in the visible region. The best hydrogen evolution efficiency was 102.12 μmol · g−1 · h−1 when the treated temperature was 900 °C (Cu–Beta–900). The temperature of the solid phase reaction had an important influence on the photocatalytic performance of Cu–Beta; a suitable reaction temperature can greatly improve its photocatalytic performance.

Photocatalytic performance of a novel semiconductor nanocatalyst: Copper doped nickel oxide for phenol degradation

In this study, the degradation of phenolic compounds was performed in the presence of pure and Cu doped nickel oxide (Cu–NiO) nanocatalysts. A wet chemical method was utilized for the catalyst preparation. The crystallinity and phase were determined using X-ray diffraction, optical properties were analyzed by UV–Vis spectroscopy and morphology was analyzed by a transmission electron microscope. Fourier transform infrared spectroscopy confirms the formation of pure NiO and the existence of copper in doped nanocatalyst samples. Cu–NiO nanocatalyst samples showed a reduction in average crystallite size as compared to pure NiO sample, where it was 24.0, 22.8 and 19.03 nm for 2Cu–NiO and 4Cu–NiO, respectively. The average particle size as determined by using transmittance electron microscopy were about 28.0, 26.6 and 22.8 nm for NiO, 2Cu–NiO and 4Cu–NiO, respectively. In addition, the energy bandgap values were found to be 3.26, 3.64 and 3.87 eV for undoped NiO, 2Cu–NiO and 4Cu–NiO, respectively. Comparative study of the photocatalytic performance of Cu–NiO and pure NiO were systematically performed at various reaction times and Cu doping ratios (2–4 wt.%). Different molar concentrations of phenol were also considered for this study. The obtained results showed that the Cu–NiO nanocatalyst exhibited the highest phenol degradation efficiency as compared to their undoped counterpart. This material is first reported and successfully used in efficient removal of phenol from real industrial effluent. The nanocatalyst efficiency for phenol removal was tested in real leather industrial wastewater effluent which could remove about 85.7% within 150 min.

Paper templated synthesis of nanostructured Cu–ZnO and its enhanced photocatalytic activity under sunlight

Cu-doped zinc oxide (Cu–ZnO) nanostructure was prepared using Whatman filter paper as a template by combustion method. For the synthesis of porous Cu–ZnO nanostructures the stoichiometric amount of precursors were impregnated in the filter papers and processed, thermally. The formation of wurtzite phase having crystallite size in the range of 20–24 nm was confirmed by X-ray diffraction (XRD) analysis. The morphological study by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) shows size of nanoparticles in the range of 25–50 nm. The optical study shows red shift i.e. extended absorbance in the visible region due to Cu doping. The photoluminescence study of Cu–ZnO results quenching in the photoluminescence peak as effect of Cu doping in ZnO lattice. Considering the extended band gap in the visible region of as synthesized Cu–ZnO, the photocatalytic dye degradation activity of methylene blue (MB) was executed in presence of sunlight irradiation. The effect of salt concentration and PH on dye degradation activity also studied. The highest photocatalytic activity was observed for Cu–ZnO with 4% doping as compared with other Cu–ZnO and ZnO nanostructure. The photocatalytic performance of Cu–ZnO shows complete degradation of MB dye within 30 min for 4% Cu–ZnO nanostructure. The photocatalytic activity obtained is much higher as compare to earlier reports. The synthesis of Cu doped ZnO by paper templated method and its photocatalytic activity is hitherto unattempted.

Cu doped ZnO hierarchical nanostructures: morphological evolution and photocatalytic property

Copper doped ZnO hierarchical nanostructures have been synthesized with a facile solution route at room temperature. Structural properties of the as-synthesized nanostructures have been studied X-ray diffraction, field emission scanning electron microscopy with energy dispersive. Meanwhile, light-absorption properties were studied with UV–Vis absorption spectroscopy. Photocatalytic performance of Cu-doped ZnO hierarchical nanostructures were evaluated by the light-driven degradation of methylene blue. The results indicated that Cu doping lead to the augment of average crystallite size of ZnO crystals. Moreover, morphological evolution of ZnO nanostructures was found with the addition of Cu ions. The photocatalytic test showed that there is an optimum Cu doping concentration which results in the enhancement of photocatalytic performance of Cu doped ZnO hierarchical nanostructures, compared with pristine ZnO. A novel and reasonable mechanism was proposed. It is believed that the enhanced photocatalytic performance of Cu doped ZnO hierarchical nanostructures can be attributed to the formation of acceptor level (Cu2+–Cu+) in the midgap of ZnO, which improved the utilization of light and separation efficiency of photogenerated electron hole pairs.

Cu-α-NiMoO4 photocatalyst for degradation of Methylene blue with pathways and antibacterial performance

Abstract Cu doped α-NiMoO 4 photocatalyst has been synthesized by microwave hydrothermal method. The existence of Cu 2+ ions at lattice position of α-NiMoO 4 was observed on the basis of XRD, HRTEM, SAED, and EDS analysis. The negative zeta potential values indicate the stability of samples. Solar light driven photocatalytic degradation of Methylene blue (MB) dye in water was used to evaluate the photocatalytic performance of Cu doped α-NiMoO 4 photocatalyst. The results revealed that there is an optimum Cu (4 mol%) doping level leads to highly enhanced photocatalytic activity of Cu-α-NiMoO 4 , as compared to α-NiMoO 4 host. The experiment also suggested that active species (OH , O 2 − and h + ) play a crucial role in the scavenging system. The reduced energy band gap, oxygen vacancy, high BET surface area, and efficient separation of photogenerated electron/hole are responsible for enhancement of photocatalytic performance. MB photodegradation intermediates were identified by high resolution-quadruple time of flight electrospray ionization mass spectrometry (HR-QTOF ESI/MS) in positive ion mode and degradation pathway was proposed. Antibacterial performance was analyzed against Gram-positive (methicillin resistant Staphylococcus aureus and Bacillus Subtilis ) and Gram-negative bacteria ( Pseudomonas aeruginosa ) via well-diffusion method. The formation of larger inhibition zone by small quantity of photocatalyst powder proved the excellent antibacterial performance. The inactivation of microorganism were found in following order: B . Subtilis ˃ S . aureus ˃ P . aeruginosa . The result of our study suggested that copper doped α-NiMoO 4 photocatalyst is suitable for degradation of organic contaminates as well as effective for growth inhibition of multidrug-resistant microorganisms.

Sensitivity analysis of the photoactivity of Cu–TiO2/ZnO during advanced oxidation reaction by Adaptive Neuro-Fuzzy Selection Technique

One of the most pivotal limitations of TiO2 or ZnO based lattices is their photocatalysis activity under visible light irradiation. In this study, a hybrid photocatalyst was generated by doping TiO2/ZnO lattice with copper in order to improve their photo-activity. The main aim was to analyse the sensitivity of photoactivity of Cu–TiO2/ZnO toward operating conditions in advanced oxidation reaction for photodegradation of two different dyes under visible light irradiation. The sol–gel-prepared composite was characterized in detail to confirm its properties in terms of band gap, crystalline structure/size, optical absorption and surface area. Then, ANFIS (Adaptive Neuro Fuzzy Inference System) was employed to investigate the effects of five independent variables including dye and catalyst concentrations, pH, intensity of light irradiation and reaction time on the photocatalytic performance of Cu–TiO2/ZnO. This process includes several ways of discovering a subset from the group of the recorded parameters and predicting which variable has the strongest effect on the response of interest. Besides, variable search was performed using the ANFIS network. According to variable selection using ANFIS analysis, catalyst concentration and reaction time were the most effective parameters for MO degradation whereas dye concentration and pH were the most influential factors on MB removal using Cu–TiO2/ZnO. Furthermore, Cu–TiO2/ZnO photocatalyst presented the maximum removal efficiency of: color: 83.35%, COD: 73.54% and TOC: 54.46% for MO degradation and color: 75.50%, COD: 68.00% and TOC: 46.41% for MB degradation.

Facile synthesis and photocatalytic performance of self-assembly CuO microspheres

Hierarchical CuO microspheres have been successfully synthesized by chemical bath deposition, during which Cu(OH)2 nanorobs firstly transform into CuO nanosheets and then these nanosheets spontaneously self-assemble to form CuO microspheres. Detailed characterization of the synthesized nanomaterials was performed utilizing X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV–Vis absorption spectra to study their crystalline phase, morphology and optical property. Additionally, photocatalytic performance of Cu(OH)2/CuO composite and pure CuO nanostructures was evaluated. Optical gaps of them are 2.75eV and 1.33eV respectively, showing a significant enhancement in the photocatalytic property in comparison with commercial CuO as demonstrated in photodegradation of methyl blue (MB). A growth mechanism for the formation of CuO nanostructure was also proposed.

Excellent visible-light-driven photocatalytic performance of Cu2O sensitized NaNbO3heterostructures

Heterostructure complexes of Cu2O/NaNbO3exhibited high catalytic activities on the degradation of methyl orange.