Photocatalytic Activity Of Cu Research Articles

Effect of different Cu:Co film concentrations on photocatalytic reactions of ethanol, MB, AMX, and Cr(VI): A study of film properties & effects of photooxidation

Wastewater treatment is an urgent challenge of the 21st century, and photocatalysis represents a promising approach. However, much of the research has focused on powdered photocatalysts and complex, costly methods, leading to limitations in practical applications. This study introduces an innovative approach to produce Cu:Co thin films with different weight ratios (70:30, 50:50, and 30:70) by the low-cost dip-coating technique. The photocatalytic activity of Cu:Co films was investigated through the photooxidation of alcohol (EtOH), degradation of dye (MB), antibiotic (AMX), and photoreduction of heavy material ions (Cr(VI)) under sunlight irradiation. The results clearly show that higher Cu concentration ratios (70:30%) resulted in smoother surfaces (49.7 nm), higher droplet contact angle (72.43°), smaller particles (67 nm), lower film thickness (365 nm), narrower band gap (1.68 eV), higher transmittance (26.7%), and improved degradation of MB (78% for 4 h) and amoxicillin (43% for 45 min). Conversely, higher Co ratios may yield contrasting effects in most cases. The photoreduction of Cr(VI) showed similar results for Cu:Co films with 70:30 and 50:50 ratios, reaching 42.81% and 43.82% for 30 min, respectively. The effect of the ethanol photooxidation process significantly reduced the roughness, film thickness, and band gap in all Cu:Co films while enhancing transmittance, except for the 50:50 Cu:Co ratio. Cu:Co films are ideal for practical applications such as photoreaction processes due to their efficiency, sustainability, and stability.

Crystallite size controlled doping of transition metals (Co, Cu) in ZnO nanocrystals to investigate microstructural, optical, magnetic, and photocatalytic properties

In this report, Co and Cu doped ZnO nanocrystals with controlled crystallite size were synthesized. The formation of the hexagonal wurtzite phase is confirmed by Rietveld refinement of X-ray diffraction (XRD) patterns. Crystallite size ranges (17 nm–20 nm) obtained from XRD analysis are complemented with transmission electron microscopy (TEM) observation. The presence of E2high mode recognized the unchanged phase and good crystalline nature of the nanocrystals. Photoluminescence (PL) spectra of Co and Cu doped ZnO nanocrystals are related to zinc and oxygen based defect states. The quenching of PL intensity is due to the incorporation of Co and Cu in the ZnO nanocrystals. ESR results complement the decrease in ferromagnetic order as obtained by VSM measurement in both Co and Cu doped ZnO nanocrystals. The superior photocatalytic activity of Cu doped ZnO nanocrystals could be due to the higher electron trapping capability of Cu2+ ions.

Enhanced photocatalytic activity of Cu and Ni-doped ZnO nanostructures: A comparative study of methyl orange dye degradation in aqueous solution

Heterogeneous photocatalysis has been considered one of the most effective and efficient techniques to remove organic contaminants from wastewater. The present work was designed to examine the photocatalytic performance of metal (Cu and Ni) doped ZnO nanocomposites in methyl orange (MO) dye degradation under UV light illumination. The wurtzite hexagonal structure was observed for both undoped/doped ZnO and a crystalline size ranging between 8.84 ± 0.71 to 12.91 ± 0.84 nm by X-ray diffraction (XRD) analysis. The scanning electron microscope (SEM) and energy dispersive X-ray (EDX) revealed the irregular spherical shape with particle diameter (34.43 ± 6.03 to 26.43 ± 4.14 nm) and ensured the purity of the individual elemental composition respectively. The chemical bonds (O–H group) and binding energy (1021.8 eV) were identified by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results respectively. The bandgap energy was decreased from 3.44 to 3.16 eV when Ni dopant was added to the ZnO lattice. The comparative photocatalytic activity was observed in undoped and doped nanocomposites and found to be 76.31%, 81.95%, 89.30%, and 83.39% for ZnO, Cu/ZnO, Ni/ZnO, and Cu/Ni/ZnO photocatalysts, respectively, for a particular dose (0.210 g) and dye concentration (10 mg L−1) after 180 min illumination of UV light. The photocatalytic performance was increased up to 94.40% with the increase of pH (12.0) whereas reduced (35.12%) with an increase in initial dye concentration (40 mg L−1) using Ni/ZnO nanocomposite. The Ni/ZnO nanocomposite showed excellent reusability and was found 81% after four consecutive cycles. The best-fitted reaction kinetics was followed by pseudo-first-order and found reaction rate constant (0.0117 min−1) using Ni/ZnO nanocomposite. The enhanced photodegradation efficiency was observed due to decreases in bandgap energy and the crystalline size of the photocatalyst. Therefore, Ni/ZnO nanocomposite could be used as an emerging photocatalyst to degrade bio-persistent organic dye compounds from textile wastewater.

Synthesis of a 3D Cu(II) MOF and its heterostructual g-C3N4 composite showing improved visible-light-driven photodegradation of organic dyes

One 3D Cu(II)-based metal-organic framework {[Cu3(tmpa)2(1,2,3-btc)2(H2O)2].14H2O.2DMF}n (Cu(tmpa)) (tmpa ​= ​tris(4-(2-methyl-1H-imidazole-1-yl)phenyl)amine, 1,2,3-H3btc ​= ​1,2,3-benzenetricarboxylic acid) was prepared by hydrothermal method and characterized. Cu(tmpa) exhibits (3,3,4)-connected 3D topology showing point symbol of (6·8·9)2(6·8·10)2(62·82·102). The heterostructural Cu(tmpa)/CN composites with different mass proportions were prepared and characterized by XRD, FT-IR, SEM, EDS, UV-DRS, TGA, PL and EIS. The photocatalytic activities of Cu(tmpa) and Cu(tmpa)/20%CN composite to degrade methylene blue (MB), methyl violet (MV), malachite green (MG), and Congo red (CR) were investigated. The photocatalytic degradation of MB by Cu(tmpa)/CN with different mass proportions was studied, and the catalytic conditions catalyst dosage, H2O2 concentration and initial pH value with were optimized. The degradation rate of MB for Cu(tmpa)/20%CN could reach 92.0% within 20 ​min. Cu(tmpa)/20%CN could also degrade 92.0%, 92.9% and 98.2% of MV, MG and CR in 60 ​min, 35 ​min and 3 ​min, respectively. The degradation mechanisms for MB and CR were studied. The enhanced photocatalytic activities of Cu(tmpa)/CN composite might be attributed not only to the vigorous visible-light absorption of Cu(tmpa), but also to the heterojunction formed by doping g-C3N4, which accelerates the divorce and movement of photogenerated charges compared to Cu(tmpa). The holes were the primary active matters in the degradation for MB. The holes and superoxide radicals were the main reactive matters in degradation of CR. Cu(tmpa) and Cu(tmpa)/20%CN are good photocatalytic materials.

The effect of different reaction media on photocatalytic activity of Au- and Cu-decorated zeolitic imidazolate Framework-8 toward CO2 photoreduction to methanol

In carbon capturing processes, developing efficient technologies to convert CO2 into added-value chemicals is of enormous interest. Here, in continuation of our earlier works, the influence of various reaction media in the conversion of CO2 to methanol through a photocatalytic system using Cu- and Au-decorated zeolitic imidazolate framework-8 (ZIF-8) nanocomposites (Au/ZIF-8, and Cu/ZIF-8) has been explored. To this purpose, different analytical techniques like XRD, FT-IR, EDS, FESEM, TEM, BET, PL spectroscopy, and DRS have been employed to confirm the textural properties as well as band gap estimation of the photocatalysts. Then, the activity of the as-made nanocomposites towards CO2 reduction to methanol in the presence of UV/Vis irradations at different reaction media is assessed by a batch reactor system. The obtained results indicated that when 0.1 ​M Na2SO3 and 0.2 ​M NaOH solutions are utilized instead of pure water, the yield of methanol produced in the presence of pristine ZIF-8 increases by roughly 5 and 3 times, respectively. Furthermore, it was observed although Au/ZIF-8, and Cu/ZIF-8 nanocomposites exhibited narrow band gap energy compared to pristine ZIF-8, they didn't reveal noticeable activity when they were employed in a pure water as reaction media. Both Au/ZIF-8 and Cu/ZIF-8 photocatalysts show exceptional yields of 2650 ​μmol.g−1cat and 2240 ​μmol.g−1cat when 0.1 ​M Na2SO3 solution is used, compared to 1300 ​μmol.g−1cat for pristine ZIF-8 at the same medium. We believe that the decoration of MOF materials with Au and Cu nanoparticles (NPs) can benefit because of the high surface area of MOF structures and the good photocatalytic activity of Cu and Au NPs for photoreduction of CO2, if an appropriate medium is chosen for the reaction.

Visible-light-driven reduction of chromium (VI) by green synthesised cuprous oxide nanoparticles

• The Prunus cerasifera extract used as a greener reducing agents for the synthesis of Cu 2 O NPs. • XRD, FT-IR, SEM and EDX confirms the formation and morphology of Cu 2 O NPs. • Efficient visible light reduction of Cr(VI) to Cr(III) achieved by Cu 2 O NPs. • Statistical optimization based on Response surface methodology predicts 99 % reduction. The photocatalytic reaction is the best alternative for the reduction of hexavalent chromium (Cr (VI)) to a less toxic trivalent chromium (Cr (III)). However, getting photocatalysts working in the visible region is yet the key issue for the field. Hence, we have reported an environmentally friendly, and cost-effective synthesis of visible light active cuprous oxide (Cu 2 O) using prunus cerasifera plant extract. The phytochemicals from Prunus cerasifera extract are used as surface modifying and reducing agents for the synthesis of Cu 2 O nanoparticles (NPs). The powder XRD, FT-IR spectroscopy, SEM and EDX instruments were used to confirm the crystal structure, morphology and composition of Cu 2 O NPs. Photocatalytic activity of Cu 2 O NPs investigated via the reduction of Cr (VI) under visible light irradiation. The results showed that Cu 2 O NPs can efficiently reduce Cr (VI). Response surface methodology coupled with Box Behnken Design (RSM-BBD) statistical model was used to optimize the photocatalysis factors and predicted 99% reduction efficiency at pH = 5.95, time 160 min and 15.68 mg/L Cr (VI). The kinetics and plausible mechanism were proposed based on the experimental results.

Influence of Urbach energy in enhanced photocatalytic activity of Cu doped ZnO nanoparticles

This article reports the photocatalytic activity of Copper doped Zinc oxide nanoparticles synthesized using a simple co-precipitation method. The samples synthesized were characterized by XRD, FESEM, nitrogen surface area analysis, UV–Vis spectroscopy and photoluminescence studies. XRD investigations have confirmed the formation of the wurtzite phase. The direct bandgap of the material has been obtained by UV–vis absorption analysis and the bandgap narrowing is observed. Room temperature photoluminescence studies at an excitation wavelength of 330 nm show emission in the UV and visible regions. Furthermore, to estimate the photocatalytic activity of the prepared sample, the degradation activity against methyl orange dye has been investigated successfully. Cu doped samples show a better photocatalytic activity than the pure ZnO sample and the contribution of Urbach energy in photocatalytic activity has been discussed.

Synthesis, characterization and photo-electrochemical properties of novel Cu(Cr1-,Al )2O4 spinel oxides for enhanced photodegradation of organic dyes under UV light

In the present work, physical, photo-electrochemical properties and photocatalytic activity of Cu(Cr 1- x ,Al x ) 2 O 4 ( x = 0, 0.1, 0.5, 0.9 and 1) spinels synthesized via the nitrate route were investigated for the first time. X-ray diffraction (XRD) with Rietveld refinement confirms the purity of all samples while SEM images show the porous and spongious morphology of the oxides of 62–311 nm grain sizes. The chemical composition and the oxidation states were determined by X-ray photoelectron spectroscopy (XPS) analysis. The specific surface area is highly affected by x -ratio. The photoelectrochemical behavior of the synthesized materials was evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Mott-Schottky in Na 2 SO 4 electrolyte (0.1 M). Indeed, the electrochemical tests under the effect of light show an increase in the current intensity and a decrease in the charge transfer resistance in CV and EIS tests, respectively. These materials were applied as photocatalysts for the photodegradation of Methylene Blue (MB) under UV light with the aid of H 2 O 2 serving as generator of free radicals. Our results show that Cu(Cr 0.1 ,Al 0.9 ) 2 O 4 is the most performant photocatalyst of MB with a degradation efficiency of 98.8% within 80 min of irradiation. Furthermore, the photocatalytic activities of Cu(Cr 0.1 ,Al 0.9 ) 2 O 4 were evaluated by the degradation of Rhodamine B (RhB) and Methyl Orange (MO) and the results reveal a good performance toward RhB degradation (85.5%), and to a lesser degree for MO decomposition (67.3%). • Cu(Cr 1- x ,Al x ) 2 O 4 oxides are synthesized by nitrate reaction for the first time. • Physicochemical properties and photocatalytic activity are investigated. • Efficient degradation of the dye within 10 min of irradiation up to 96.36%. • Cu(Cr 0.1 ,Al 0.9 ) 2 O 4 is the most performant photocatalyst of MB degradation (98.8%). • Efficient decomposition of RhB and MO by Cu(Cr 0.1 ,Al 0.9 ) 2 O 4 .

Synergistic influence of FRET, bulk recombination centers, and charge separation in enhancing the visible-light-driven photocatalytic activity of Cu2+-ion-doped ZnO nanoflowers.

Pure ZnO and a group of Cu2+-ion-doped (4, 6, and 8 wt%) ZnO nanomaterials are synthesized using the co-precipitation technique. X-ray diffraction and Fourier transform infrared spectroscopy confirm both the substitution of Zn2+ ions by Cu2+ ions in the ZnO lattice and formation of the ZnO/CuO composite. The divalent oxidation state of Cu is confirmed using X-ray photoelectron spectroscopy. A suppression in the oxygen vacancy density is observed up to a doping level of 6 wt%, but beyond that it increases. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show a cross-linked nanoflower-like structure. The presence of a separate CuO phase is also confirmed via TEM. Absorption spectroscopy yields a reduction in the bandgap up to 6 wt%, after which it is increased for 8 wt%. An enhanced plasmon band in the spectra reveals the presence of CuO. The photoluminescence is quenched for doping up to 6 wt%, and with further doping the emission is enhanced. These observations are explained by the doping-concentration-dependent Förster resonance energy transfer (FRET) phenomenon between the ZnO (donor) and the CuO (acceptor). For the highest doping concentration, the emission profile shows a sudden enhancement resulting from the simultaneous competition of two FRET mechanisms (the intra-acceptor mechanism and the inter-donor-acceptor mechanism). By contrast, for other doped nanomaterials, the inter-donor-acceptor FRET mechanism with doping-concentration dependence is able to explain the suppression of the emission intensity. All doped nanomaterials show an improved visible-light-driven photocatalytic efficiency compared with pure ZnO for methylene blue, which results from the synergistic effects of a reduction in the concentration of bulk defects, enhanced charge separation, and FRET. The highest photocatalytic performance is demonstrated by the 6 wt% nanomaterial due to its optimum doping concentration. However, beyond this concentration, the formation of excessive CuO on the surface of ZnO increases the concentration of bulk defects, and the simultaneous occurrence of the inter-donor-acceptor FRET and intra-acceptor FRET mechanisms takes place leading to the rapid recombination of electron-hole pairs and reduced photocatalytic activity.

Cu3P nanoparticles decorated hollow tubular carbon nitride as a superior photocatalyst for photodegradation of tetracycline under visible light

• Cu 3 P/HTCN composite was successfully prepared via a simple solvothermal method. • Unique hollow tubular structure greatly improves the light harvesting ability. • Cu 3 P/HTCN composite shows superior photocatalytic activity for degradation of TC. • Cu 3 P effectively inhibits the rapid recombination of photogenerated carrier of HCCN. The construction of stable, efficient and economical visible-light-driven photocatalyst is a practical strategy to deal with antibiotic water contamination. Herein, Cu 3 P nanoparticles/hollow tubular carbon nitride (HTCN) composite was successfully prepared and the photocatalytic activity of Cu 3 P/HTCN was evaluated with tetracycline (TC) as the degradation target antibiotic. Among them, the 6% Cu 3 P/HTCN exhibited optimal photocatalytic degradation rate (96.9% in 40 min), which was 8.3 times higher than that of pure HTCN. The enhancement of photocatalytic performance by Cu 3 P/HTCN is attributed to the introduction of Cu 3 P nanoparticles can not only increase the specific surface area of HTCN to provide abundant reaction sites, but also enhance the capture ability of incident light and promote the high-speed separation and transfer of photogenerated charges. In addition, the electron spin resonance (ESR) technology was used to further confirm that the main active species during the photocatalytic degradation of TC. Furthermore, the possible intermediates in photocatalytic degradation of TC by Cu 3 P/HTCN was the identified with liquid chromatography-mass spectrometry (LC-MS). This work provides an effective way for constructing HTCN-based composite materials for photocatalytic application.

Effects of Cu doping on the phase transition and photocatalytic activity of anatase/rutile mixed crystal TiO2 nanocomposites

Pure and Cu doped anatase/rutile mixed TiO2 nanomaterials were fabricated through sol-gel method. The obtained photocatalysts were characterized by XRD, SEM, TEM, XPS, PL and DRS, and the influences of Cu doping on the structure and photocatalytic property were studied. The results show that when the molar ratios of Cu/Ti are 1% and 2%, Cu doping promotes anatase → rutile phase transformation. When the molar ratio of Cu/Ti is 4%, the phase transformation is inhibited. Cu element coexists in the form of Cu+ and Cu2+, and Cu doping facilitates the separation of photogenerated electrons and holes. TEM image shows that copper oxides are dispersed on TiO2 particles surface, which significantly reduces the optical absorption of ultraviolet region. The photocatalytic experiment results show that the photocatalytic activity of Cu–TiO2 is lower than pure TiO2, and the higher doping concentration, the lower photocatalytic activity.

Versatile fabrication and characterization of Cu-doped ZrO2 nanoparticles: enhanced photocatalytic and photoluminescence properties

Pristine ZrO2 and molar ratios of Cu-doped ZrO2 nanoparticles were synthesized by chemical precipitation. The XRD pattern of pristine ZrO2 and Cu-doped ZrO2 nanoparticles shows the formation of t-tetragonal phase and shifting of tetragonal phase to monoclinic phase. The average crystallite sizes of the pristine ZrO2 and Cu-doped ZrO2 nanoparticles were calculated as 2.9, 4.65, 4.76, 5.02, and 4.96 nm, respectively. The Cu (0.06 M)-doped ZrO2 nanoparticles are present as spherical morphology and high agglomeration was confirmed by FE-SEM and TEM analyses. The XPS spectra affirmed the presence of Cu2+, Zr4+, and oxygen ions in the Cu (0.06 M)-doped ZrO2 nanoparticles. The Cu-doped ZrO2 nanoparticles exhibit two energy gaps at 5.30 and 3.05 eV, 5.21 and 2.22 eV, 4.65 and 2.11 eV, and 4.44 and 2.65 eV. The surface defects and oxygen vacancies were analyzed by PL and ESR spectroscopy. The ESR spectra are clearly asymmetric in shape and contain a peak signal related to the presence of the copper species (Cu2+) in the distorted tetragonal coordination of ZrO2. The photocatalytic activities of Cu (0.06 M)-doped ZrO2 nanoparticles were successfully sought on degradation of the two azo dyes: methyl violet and methyl blue under sunlight irradiation. Cu (0.06 M)-doped ZrO2 showed complete degradation at 70 min. The reusability of Cu (0.06 M)-doped ZrO2 nanoparticles shows maximum degradation efficiency for six successive runs.

Single-step sonochemical synthesis of Cu2O-CeO2 nanocomposites with enhanced photocatalytic oxidative desulfurization.

In this paper, for the first time, composite nanostructures of Cu2O-CeO2 were prepared by a facile and single-step sonochemical method for thiophene photocatalytic oxidative desulfurization. Sonication was performed utilizing a high-intensity ultrasonic probe with a maximum output power of 80 Wcm-3 and operating frequency at 20kHz. The direct effect of ultrasonic waves on the composition and morphology of the obtained products was also evaluated and it was found that under ultrasonic irradiation, Cu2O-CeO2 can be produced while the main product in the absence of ultrasonic waves is CuO-CeO2. Cu2O-CeO2 exhibits much higher photocatalytic efficiency (84%) than CuO-CeO2 (39%) due to its higher light absorption and electron synergistic effect. The effect of Ce:Cu on photocatalytic efficiency was examined by considering the ratios of 1:0.25, 1:1, 0.5:1, and 0.25:1 and yields of 64, 81, 84, and 76% were obtained, respectively. This indicates that there is an optimal value for the Ce:Cu ratio in the Cu2O-CeO2 nanocomposite.

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

Modified titania photocatalyst powder samples were prepared using the sol-gel method for copper (Cu) and cerium (Ce) doping and impregnation for platinum (Pt) loading. Their bulk crystalline structures were investigated using X-ray diffractometry (XRD) with the Rietveld analysis. The surface/bulk structure, surface properties, and morphologies were observed using reversed double-beam photoacoustic spectroscopy (RDB-PAS), nitrogen adsorption, and scanning electron microscopy, respectively. The results from the XRD revealed that all samples were mainly anatase (ca. 80% or higher) with small amounts of rutile and non-crystalline components. The specific surface areas of all samples were in the range of 115–155 m2 g−1. Ce and Cu species were mainly distributed, while Pt was potentially loaded as a partially oxidized form on the titania surface. The results from the RDB-PAS indicated the changing of the energy-resolved distribution of electron traps (ERDT) from the original titania surface upon doping of the metals (Cu, Ce, and Pt), which altered their catalytic activities. The metals photocatalytic activities with UV irradiation were measured in two representative reactions; (a) CO2 evolution from acetic acid under the aerobic condition and (b) H2 evolution from deaerated aqueous methanol. In reaction (a), the Cu and/or Ce modification gave almost the same or slightly lower activity compared to the non-modified titania samples, while platinum loading yielded ca. 5–6 times higher activity. For reaction (b), the photocatalytic tests were divided into two sets; without (b1) and with (b2) Pt deposition during the reaction. Similar enhancements of activity from the Pt loading sample (and by Cu modification) were observed in reaction (b1) without in-situ platinum deposition, while the unmodified and Ce-doped samples were almost inactive. For the activities of reaction (b2) with in-situ platinum deposition, the unmodified samples showed the highest activity while the Cu-modified samples showed significantly lower activity.

One‐step solvothermal synthesis of Cu–Cu 2 O composite with improved photocatalytic activity under visible light irradiation

Microspheres-like Cu–Cu2O composites were successfully fabricated through a facial one-step solvothermal method. The phase and morphology of Cu-Cu2O composites were characterised by X-ray diffraction, scanning and transmission electron microscopy, and high-resolution transmission electron microscopy. Also, the photodegradation experimental of methyl orange (MO) displayed that the as-obtain Cu–Cu2O composites possess excellent photocatalytic activity. After 120 min visible light irradiation, the photodegradation rate of MO on pure Cu2O and Cu–Cu2O was up to 11.8 and 90.6%, respectively. Moreover, the photodegradation rate of MO on Cu–Cu2O was 19.5 times than that on pure Cu2O. The great photocatalytic activity of Cu–Cu2O composites might be ascribed to the appropriate amount of Cu, which could promote the transfer of photo-generated electrons and restrain the recombination of electron–hole.

Visible light photocatalytic activity of Cu, N co-doped carbon dots/Ag3PO4 nanocomposites for neutral red under green LED radiation

In current investigation, we synthesized a new Cu, N co-doped carbon dots/Ag3PO4 (Cu, N-CDs/Ag3PO4) nanocomposite by one-step thermolysis and precipitation method. In addition, we evaluated the activity of Ag3PO4 and Cu,N-CDs/Ag3PO4 nanomaterials in degrading an environmental pollutant called neutral red under visible radiations. Compared to the pure Ag3PO4, Cu, N-CDs/Ag3PO4 had shown high degradation efficiency by more than 25% and shown good recyclability. The synthesized nanocomposite was characterized by XRD, HRTEM, FT-IR, Raman and XPS techniques. The optical property of Cu, N-CDs/Ag3PO4 nanocomposite was examined with UV–vis DRS (Diffuse Reflectance Spectroscopy). And the excellent photocatalytic performance of this Cu, N-CDs system was ascribed to the increased conversion of ·O2− under visible light irradiations and effective separation of electron-hole pairs, results in inhibited photocorrosion of the system. Also, this nanocomposite could successfully degrade the neutral red dye (mention the concentration) about 95.5% under LED irradiations within 60 min.

Superior photocatalytic activity of Cu doped NiWO4 for efficient degradation of benzene in air even under visible radiation

We effectively used Cu dopant to improve photocatalytic performance of NiWO4 to remove benzene in air. The obtained experimental result indicated that photocatalytic performance of the prepared Cu-NiWO4 materials were greater than that of the pure NiWO4. This was because Cu effectively acted as novel dopant, which not only affected valence band (VB) top and conduction band (CB) bottom of NiWO4 but also formed a medium energy level between CB and VB of the NiWO4 to decrease its energy band gap and electron-hole recombination rate. Hence, the photocatalyst produced large available charge amounts (electron and hole) initiating photocatalysis for degradation of gaseous benzene. The optimized Cu/Ni mole ratio for maximum improving photocatalytic performance of NiWO4 was 3%. The maximum benzene removal efficiency and its mineralization via visible light photocatalysis of the 3Cu-NiWO4 were 93.7 and 96.5%, respectively. The synthesized Cu-NiWO4 photocatalyst also presented great stability in benzene removal processes.

Effect of plasmonic Ag nanowires on the photocatalytic activity of Cu doped Fe2O3 nanostructures photoanodes for superior photoelectrochemical water splitting applications

The Present study focuses on the synthesis and analysis of Cu doped hematite (α-Fe2O3) nanostructures for effectively enhancing the optical properties as well as their implementation as photoelectrodes for energy-harvesting applications. In addition to this, the influence of noble metal plasmonic layer of Ag nanowires as a bottom layer for undoped and doped Fe2O3 photoanodes has been investigated. Herein, we studied the influence of dopant on morphology, structural, and optical properties of Fe2O3. X-ray diffraction technique and X-ray photoelectron spectroscopy analysis were confirmed Cu ion substitution into host Fe2O3 nanostructures. The optical band gap decreases from ~ 1.95eV to ~ 1.38eV with increasing of Cu dopant concentration. Impedance analysis reveals that the Cu dopant works as an electron donor and improves the Fe2O3 charge carrier density. The photoelectrochemical water splitting studies reveals that the photoanodes without plasmonic layer was shown improved photocurrents compare to the undoped sample, thus improving the absorption of the incident light. Significantly, the optimized 0.2mol% Cu-doped α-Fe2O3 photoelectrodes without Ag layer reached the maximum photocurrent density of ~0.31mA/cm2, ~ 28-fold that of pure Fe2O3 (0.011mA/cm2). Further, the same photoanode with plasmonic Ag nanowires showed a significantly improved photocurrent density of 1.48mA/cm2, which is ~ 135-fold that of pure Fe2O3 and ~ 5-folds that of 0.2mol% Cu doped α-Fe2O3 photoelectrodes without plasmonic nanowire layer. The superior photocurrent is ascribed to the enhanced electron donor density and reduced charge recombination rate, as an outcome of optimized Cu doping and Ag nanowires.

Synergistic Effect of POMCPs and PPy for Enhancing Visible-Light Photocatalytic Activity and High Quantum Yields

A new Keggin-type POMs based Cu-bib (bib = 1,4-bis(imidazol-1-ylmethyl)benzene) coordination polymer with appropriate surface areas and rich active sites, [Cu(bib)][H3PW12O40]·(Hbib)2·2H2O (Cu(bib)PW12), was successfully synthesized and structurally characterized. To improve the photocatalytic activity of Cu(bib)PW12, polypyrrole (PPy) was loaded on its surface through a facile in situ oxidation polymerization process. Under the irradiation of visible light, the composites (Cu(bib)PW12/PPy (A and B) exhibited excellent photocatalytic activities for the degradation of methylene blue than pure Cu(bib)PW12 crystal, PPy and their mechanically mixing (Cu(bib)PW12/PPy (A′ and B′), respectively. Catalytic mechanism study indicates that the enhancement of photocatalytic activities of Cu(bib)PW12/PPy can be attributed to the higher separation efficiency of the photogenerated electron–hole pair on the interface of PPy and Cu(bib)PW12. These results suggest that loading PPy onto the surface of POMCPs would be a feasible strategy to enhance the photocatalytic activity of POMCPs.

Photocatalytic activity of Cu2O/ZnO nanocomposite for the decomposition of methyl orange under visible light irradiation

Abstract ZnO is modified by Cu2O by the process of precipitation and calcination. X-ray diffraction has shown that Cu2O/ZnO catalysts are made of highly purified cubic Cu2O and hexagonal ZnO. Scanning electron microscopy and transmission electron microscopy have shown that ZnO adhered to the surface of Cu2O. Due to the doping of Cu2O, the absorption range of the Cu2O/ZnO catalyst is shifted from the ultraviolet to the visible region due to diffuse reflection. X-ray photoelectron spectroscopy and photoluminescence spectra have confirmed that there is a substantial interaction between the two phases of the resultant catalyst. The degradation efficiency of Cu2O/ZnO on methyl orange solution is obviously enhanced compared to Cu2O and ZnO. The maximum degradation efficiency is 98%. The degradation efficiency is affected by the pH of the solution and initial concentration. After three rounds of recycling, the degradation rate is almost same. This shows a consistent performance of Cu2O/ZnO. The increase in catalytic ability is related to the lattice interaction caused by the doping of Cu2O.