Tuneable quantised conductance memory states in TiO2based resistive switching devices in crossbar geometry for high density memory applications.

The tunability and controllability of conductance quantization mediated multilevel resistive switching (RS) memory devices, fabricated in crossbar geometry can be a promising alternative for boosting storage density. Here, we report fabrication of Cu/TiO2/Pt based RS devices in 8 × 8 crossbar geometry, which showed reliable bipolar RS operations. The crossbar devices showed excellent spatial and temporal variability, time retention and low switching voltage (<1 V) and current (∼100µA). Furthermore, during the reset switching, highly repeatable and reliable integral and half-integral quantized conductance (QC) was observed. The observed QC phenomenon was attributed to the two dimensional confinement of electrons as lateral width of the conducting filament (CF) matches the fermi wavelength. The magnitude and number of the QC steps were found to increase from ∼2.5 to 12.5 and from 5 to 18, respectively by increasing the compliance current (IC) from 50 to 800µA which also increased the diameter of the CF from ∼1.2 to 3.3 nm. The enhancement in both number and magnitude of QC states was explained using electrochemical dissolution mechanism of CF of varying diameter. A thicker CF, formed at higherIC, undergoes a gradual rupture during reset process yielding a greater number of QC steps compared to a thinner CF. The realisation of QC states in the crossbar Cu/TiO2/Pt device as well asICmediated tunability of their magnitude and number may find applications in high-density resistive memory storage devices and neuromorphic computing.

Photocatalytic performance and interaction mechanism of reverse micelle synthesized Cu-TiO2 nanomaterials towards levofloxacin under visible LED light.

The degradation performance of Cu-TiO2 nanomaterials towards levofloxacin (LFX) antibiotic was investigated under an environmentally benign visible LED light source. Cu-TiO2 nanomaterials were prepared using the reverse micelle sol-gel method with different copper content ranging from 0.25 to 1.0 wt% concerning titania. Characterization of Cu-TiO2 samples was performed by XRD, TEM, UV-Vis, BET, ICP-MS, FTIR and XPS techniques. 0.5 wt% Cu-TiO2 showed crystallite size below 6 nm, surface area (69.85 m2/g) and significant visible light absorption capacity. Both Cu1+ and Cu2+ are formed in lower Cu-doped TiO2 samples, whereas only Cu2+ is present in higher Cu-doped TiO2 samples as evident in XPS analysis. 0.5 wt% Cu-TiO2 has shown the optimum photocatalytic degradation of 75.5% under 6 h. of a visible light source. FTIR analysis of LFX adsorbed Cu-TiO2 materials indicated the pollutant-catalyst interaction, where the declining trend was observed in photocatalytic degradation efficiency for higher Cu-doped TiO2 samples due to copper-LFX complex formation. Copper-LFX complexes are formed due to the presence of Cu2+ in higher Cu-doped TiO2 nanomaterials, which might have hindered the photocatalytic activity under visible light. Effects of initial pollutant concentration, catalyst loading and visible light intensity on the degradation of LFX are studied. Photocatalytic degradation pathways of LFX using best performing Cu-TiO2 material were also proposed based on the LC-MS analysis.

Improving Performance of an Integrated Solar Flow Battery by Cr- and Cu-Doped TiO2 Photoelectrodes.

This work reports on the preparation of Cr-doped TiO2 (Cr−TiO2), Cu-doped (Cu-TiO2), and its utilization in the photoanode of a solar redox flow battery (SRFB). A pure TiO2 electrode, Cr-doped TiO2 electrode, and Cu-doped TiO2 electrode coated with different layers are prepared by the sol-gel method. XRD, XPS, and SEM are used to characterize the relevant data of the electrode. All three electrodes show the structure of the anatase phase, but the Cu-TiO2 and Cr-TiO2 electrodes are more crystalline. Using these materials as photoelectrodes to prepare integrated solar flow cells, the semi-cell and full-cell tests show that the doping of Cr and Cu improves the efficiency and charging current of solar cells. The average charging currents of the Cu-TiO2 and Cr-TiO2 electrodes are 384.20 µA and 450.75 µA, respectively, compared with the TiO2 electrode; this increment reaches values of 71.23% and 100.97%.

Impact of TiO2 Reduction and Cu Doping on Bacteria Inactivation under Artificial Solar Light Irradiation.

Preparation of TiO2 using the hydrothermal treatment in NH4OH solution and subsequent thermal heating at 500-700 °C in Ar was performed in order to introduce some titania surface defects. The highest amount of oxygen vacancies and Ti3+ surface defects were observed for a sample heat-treated at 500 °C. The presence of these surface defects enhanced photocatalytic properties of titania towards the deactivation of two bacteria species, E. coli and S. epidermidis, under artificial solar lamp irradiation. Further modification of TiO2 was targeted towards the doping of Cu species. Cu doping was realized through the impregnation of the titania surface by Cu species supplied from various copper salts in an aqueous solution and the subsequent heating at 500 °C in Ar. The following precursors were used as a source of Cu: CuSO4, CuNO3 or Cu(CH3COO)2. Cu doping was performed for raw TiO2 after a hydrothermal process with and without NH4OH addition. The obtained results indicate that Cu species were deposited on the titania surface defects in the case of reduced TiO2, but on the TiO2 without NH4OH modification, Cu species were attached through the titania adsorbed hydroxyl groups. Cu doping on TiO2 increased the absorption of light in the visible range. Rapid inactivation of E. coli within 30 min was obtained for the ammonia-reduced TiO2 heated at 500 °C and TiO2 doped with Cu from CuSO4 solution. Photocatalytic deactivation of S. epidermidis was greatly enhanced through Cu doping on TiO2. Impregnation of TiO2 with CuSO4 was the most effective for inactivation of both E. coli and S. epidermidis.

Dual Activation of Molecular Oxygen and Surface Lattice Oxygen in Single Atom Cu1 /TiO2 Catalyst for CO Oxidation.

The in-depth mechanism on the simultaneous activation of O2 and surface lattice O2- on one active metallic site has not been elucidated yet. Herein, we report a strategy for the construction of abundant oxygen activation sites by rational design of Cu1 /TiO2 single atom catalysts (SACs). The charge transfer between isolated Cu and TiO2 support generates abundant CuI and 2-coordinated Olat sites in Cu1 -O-Ti hybridization structure, which facilitates the chemisorption and activation of O2 molecules. Simultaneously, the Cu1 -O-Ti induced TiO2 lattice distortion activate the adjacent surface lattice O2- , achieving the dual activation of O2 and surface lattice O2- . The Cu1 -O-Ti active site switches the CO oxidation mechanism from Eley-Rideal (80 °C) to Mars-van Krevelen route (200 °C) with the increase of reaction temperature. The dual activation of O2 and surface lattice O2- can by modulating the electron properties of SACs can boost the heterogeneous catalytic oxidation activity.

Comparison of CO2 Reduction Performance with NH3 and H2O between Cu/TiO2 and Pd/TiO2.

The aim of this study is to clarify the effect of doped metal type on CO2 reduction characteristics of TiO2 with NH3 and H2O. Cu and Pd have been selected as dopants for TiO2. In addition, the impact of molar ratio of CO2 to reductants NH3 and H2O has been investigated. A TiO2 photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO2 film and Pd/TiO2 film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO2 reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO2 reduction performance with Cu/TiO2 under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:1:1 while that without UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:0.5:0.5. It is revealed that the CO2 reduction performance of Pd/TiO2 is the highest for the molar ratio of CO2/NH3/H2O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp with UV light was 10.2 µmol/g, while that for Pd/TiO2 was 5.5 µmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp without UV light was 2.5 µmol/g, while that for Pd/TiO2 was 3.5 µmol/g. This study has concluded that Cu/TiO2 is superior to Pd/TiO2 from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency.

Impact of an Engineered Copper-Titanium Dioxide Nanocomposite and Parent Substrates on the Bacteria Viability, Antioxidant Enzymes and Fatty Acid Profiling.

Due to the systematic increase in the production of nanomaterials (NMs) and their applications in many areas of life, issues associated with their toxicity are inevitable. In particular, the performance of heterogeneous NMs, such as nanocomposites (NCs), is unpredictable as they may inherit the properties of their individual components. Therefore, the purpose of this work was to assess the biological activity of newly synthesized Cu/TiO2-NC and the parent nanoparticle substrates Cu-NPs and TiO2-NPs on the bacterial viability, antioxidant potential and fatty acid composition of the reference Escherichia coli and Bacillus subtilis strains. Based on the toxicological parameters, it was found that B. subtilis was more sensitive to NMs than E. coli. Furthermore, Cu/TiO2-NC and Cu-NPs had an opposite effect on both strains, while TiO2-NPs had a comparable mode of action. Simultaneously, the tested strains exhibited varied responses of the antioxidant enzymes after exposure to the NMs, with Cu-NPs having the strongest impact on their activity. The most considerable alternations in the fatty acid profiles were found after the bacteria were exposed to Cu/TiO2-NC and Cu-NPs. Microscopic images indicated distinct interactions of the NMs with the bacterial outer layers, especially in regard to B. subtilis. Cu/TiO2-NC generally proved to have less distinctive antimicrobial properties on B. subtilis than E. coli compared to its parent components. Presumably, the biocidal effects of the tested NMs can be attributed to the induction of oxidative stress, the release of metal ions and specific electrochemical interactions with the bacterial cells.

Photocatalytic Degradation of Methylene Blue by Plasmonic Metal-TiO2 Nanocatalysts Under Visible Light Irradiation.

This study demonstrates photocatalytic activity of 1 wt% plasmonic metal (Au, Ag and Cu)­TiO2 nanocatalysts prepared via photodeposition method for the photo oxidative decomposition of methylene blue (MB 0.01 mM) under visible light (50 mWcm−2) irradiation. Plasmonic metal loaded-TiO2 photocatalysts absorb with an absorption maximum at localized surface plasmon resonance wavelengths (500­785 nm). It has been observed that pH altered the surface charge (ζ) of TiO2 (ζ = ­4.98, ­4.0 and +9.16 at pH = 10, 7 and 3, respectively). The point of zero charge (PZC) at pH 6.3 has been determined from a correlation plot between pH and ζ. Higher rate of degradation was observed at pH = 10 because of electrostatic interaction of cationic MB with anionic TiO2. Higher photocatalytic activity was shown by Cu­TiO2 followed by Au­TiO2 and Ag­TiO2 photocatalysts in comparison to TiO2-P25. This enhancement in photocatalytic efficiency is attributed to the plasmonic effect and effective charge separation at the interface between nano size metal deposits and TiO2 particles. The overall photocatalytic reaction followed pseudo first order kinetics as per Langmuir Hinshelwood kinetic equation. GC and GC-MS studies suggested the formation of thionin after demethylation and derivatives of benzene sulphonic acid which are subsequently degraded to CO2 after prolonged irradiation time.

Antibacterial Effect of a 4x Cu-TiO2 Coating Simulating Acute Periprosthetic Infection-An Animal Model.

The purpose of our study was to investigate the antibacterial effect of a spacer (Ti6Al4V) coated with 4x Cu-TiO2 in an animal model simulating an acute periprosthetic infection by Staphylococcus aureus. Ti6Al4 bolts contaminated with Staphylococcus aureus were implanted into the femoral condyle of rabbits (n = 36) divided into 3 groups. After one week in group 1 (control) the bolts were removed without any replacement. In group2 Ti6Al4V bolts with a 4x Cu-TiO2 coating and in group 3 beads of a gentamicin-PMMA chain were imbedded into the borehole. Microbiological investigation was performed at the primary surgery, at the revision surgery and after scarification of the rabbits 3 weeks after the first surgery. Blood tests were conducted weekly. The initial overall infection rate was 88.9%. In group 2 and 3 a significant decrease of the infection rate was shown in contrast to the control group. The C-reactive protein (CRP) levels declined one week after the first surgery except in the control group where the CRP level even increased. This is the first in vivo study that demonstrated the antibacterial effects of a fourfold Cu-TiO2 coating. For the future, the coating investigated could be a promising option in the treatment of implant-associated infections.

Innovatively feasible wet incipient method for preparing Cu doped TiO2 nanocomposite: Electro-optical measurement supported by quantitative quantum and classical calculations.

The Cu-doped titanium oxide (Cu/TiO2) nanocomposite was systematically prepared using the innovatively feasible incipient wet impregnation method. Notably, the samples were derived from the raw materials through water dilution only. The successful formation of the host anatase TiO2 phase was confirmed by the characteristic peaks observed in the acquired X-ray powder diffraction (XRD) spectrum, which displayed intense peaks attributed to Cu2+ scattering sites, indicating the formation of crystallite Cu/TiO2 nanostructures. Dielectric measurements revealed that Cu/TiO2 possesses a higher dielectric permittivity compared to undoped TiO2. The conductivity for both structures exhibited a decreasing trend with increasing temperature. Interestingly, the measured optical properties indicated that Cu/TiO2 exhibited the minimum energy gap and maximum refractive index. This was further validated by qualitative time-dependent density functional calculation on a stable structural model, which was confirmed through semi-empirical molecular dynamic calculations. Thus, we have demonstrated the capability of our innovatively feasible synthesis method to produce the industrially important Cu-doped TiO2.

Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping.

Hydrophilic Cu-TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.

Synthesis of new hybrid composite based on TiO2 for photo-catalytic degradation of sulfamethoxazole and pharmaceutical wastewater, optimization, performance, and reaction mechanism studies.

In this study photo-catalytic degradation of sulfamethoxazole (SMX) from aqueous solutions using carbon quantum dot (CQD)-decorated Cu-TiO2 was investigated. The as-prepared photo-catalyst samples were characterized by various FTIR, XRD, FE-SEM, TEM, EDX, BET, and DRS techniques. The investigation of effective photo-catalytic operational parameters confirmed that the complete removal of SMX (20 mg/L) can be accomplished at pH: 6.0 and light intensity: 75 mW/cm2 over a 30-min reaction time. DRS analysis demonstrated adding CQD to the Cu-TiO2 reduced its bandgap energy from 2.97 to 2.90 eV. The photo-catalytic degradation kinetics of SMX fit well with the pseudo-first-order model. The radical trapping experiment indicates that HO• and O2•- active species were more effective species for SMX degradation, and the higher inhibition effect on the SMX degradation efficiency was assigned to O2•- ions. The water matrix species-inhibited effect in SMX removal was as follows: SO42- > Cl- > NO3- > CO3- > no ions. The synthesized photo-catalyst could be recycled after six consecutive cycles of SMX degradation with an insignificant decrease in performance. The total organic carbon (TOC) analysis suggested the mineralization of SMZ by composite photo-catalysts. The minimum inhibitory concentration (MIC) for Escherichia coli remained at 12.5 mg L-1 SMX. A possible mechanism and pathway of SMX degradation in the photo-catalytic system was presented.

Catalytic Nanomedicine - A new Approach and Solution for Chronic Ulcers: Case Series.

Chronic ulcers are a major public health problem, due to their chronic nature, their poor response to treatment, the high frequency of recurrences, and their affection to the patient's quality of life. Even with the development of new therapies in the field of chronic wound care, chronic ulcers remain a clinical problem. As a novel branch of research, Catalytic Nanomedicine has offered promising results in disinfection and treatment of chronic wounds through the use of bionanocatalysts, organically functionalized mesoporous nanostructured materials with catalytic properties. Particularly, Cu/TiO2-SiO2 mixed oxide bionanocatalysts have shown favorable results for chronic ulcer healing. In this work, we present the treatment of 15 patients (8 females and 7 males, mean age of 69.59 ± 12.07 years old) affected with chronic ulcers (wound age ranging from 4 months to 10 years old, mean size of 12.94 ± 18.20 cm2) by the administration of Cu/TiO2-SiO2 bionanocatalysts embedded in a nanoemulsion matrix. In all cases, complete epithelialization and healing of the lesions was achieved (healing time from 3 to 35 weeks), without the appearance of side effects. Wound healing time was analyzed in the context of initial wound size, wound's age, patient's age, and concomitant conditions, being wound size and patient's age the main factor affecting the duration of the treatment with the bionanocatalysts.

Bisphenol S degradation via persulfate activation under UV-LED using mixed catalysts: Synergistic effect of Cu-TiO2 and Zn-TiO2 for catalysis.

A photocatalyst composed of Zn-TiO2 and Cu-TiO2 through simple physical mixing was used to activate persulfate(PS) for Bisphenol S (BPS) degradation. Zn-TiO2 and Cu-TiO2 were prepared with a sol gel method and were characterized by X-ray diffraction (XRD), Raman, Transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The two catalysts have shown an obvious synergistic effect in the photocatalytic degradation process. When 5 mM persulfate and 0.3 g/L catalyst were used, the removal rate of mixed catalyst (0.2 g/L Zn-TiO2 and 0.1 g/L Cu-TiO2) is 100 % in 18 min, which is significantly better than that of 0.3 g/L Zn-TiO2(58 %) and 0.3 g/L Cu-TiO2(90 %). Typically, the effects of various operation parameters, including the ratio of Cu-TiO2/Zn-TiO2, catalyst dosage, persulfate dosage, initial concentration of BPS, and initial solution pH, were examined. Reactive oxygen species (ROS) in the UV/mixed catalyst/PS process was identified by scavenger and electron paramagnetic resonance (EPR) tests. The superoxide radicals generated by both Zn-TiO2 and the hydrolysis of persulfate in the system could accelerate the Cu (II)/Cu(I) redox cycles and results in the synergistic effect. This study proposed a new and effective way to improve the reaction by simply combining two catalysts, and unraveled the mechanism behind the synergistic effect, which could provide new ideas to use the catalyst more effectively for wastewater treatment or other areas.

Efficient hydrogen generation of vector Z-scheme CaTiO3/Cu/TiO2 photocatalyst assisted by cocatalyst Cu nanoparticles.

Herein, the CaTiO3/Cu/TiO2 all-solid-state Z-scheme heterojunction is successfully designed via Cu nanoparticles situating at the interface between CaTiO3 and TiO2 with a new synthesis route. Interestingly, TiO2 nanosheets are generated in-situ on the surface of CaTiO3 in the second step hydrothermal reaction. The lifetimes of photoexcited carriers, photoluminescence emission spectra and transient photocurrent response tests have confirmed that the efficient Z-scheme charge transmission path of the CaTiO3/Cu/TiO2 is beneficial to facilitate the separation of photogenerated carriers and reduce their recombination efficiency. As expected, the hydrogen generation rate of CaTiO3/Cu/TiO2 is increased to 23.550 mmol g-1h-1 with the appropriate amount of copper loading, which is about 981 times and 93 times higher than that of pristine CaTiO3 (0.024 mmol g-1h-1) and CaTiO3/TiO2 (0.253 mmol g-1h-1), respectively. Furthermore, the CaTiO3/Cu/TiO2 sample shows good stability in cycle experiments. Particularly, experimental results show that the non-noble metal Cu nanoparticles can be an effective electron mediator. And these merits strongly demonstrate that the CaTiO3/Cu/TiO2 composites have potential application in photocatalytic field. This study can provide fundamental guidance for designing rationally efficient non-noble metal vector Z-scheme system photocatalysts with outstanding photocatalytic H2 generation performance.

Improved photocatalytic conversion of high-concentration ammonia in water by low-cost Cu/TiO2 and its mechanism study.

Platinized TiO2 (Pt/TiO2) as a benchmark photocatalyst shows superior photocatalytic performance in environmental remediation. In order to reduce the cost of photocatalyst for practical use, a series of cooper loaded TiO2 (Cu/TiO2) photocatalysts were prepared by photoreduction method and compared with pure TiO2 and Pt/TiO2 in terms of overall ammonia conversion efficiency and selective oxidation. The as-prepared Cu/TiO2 samples were characterized and analyzed by physicochemical instrumental measurements. The results show that about 60% Cu2+ ions in suspension can be photodeposited onto the surface of TiO2 under UV light irradiation, and is mainly composed by a mixture of Cu/Cu+. The Cu/P25 (0.3 wt% Cu) sample was screened out as the optimal photocatalyst, via photoilluminance spectra analysis and photocatalytic oxidation of ammonia. It shows even better performance compared to Pt/TiO2 in the oxidation of high concentration of ammonia, due to the strong coordination effect by Cu(NH3)n complex formation. Through Electron Spin Resonance (EPR) analysis, and free radical suppression experiments, the active oxidative species account for ammonia oxidation and selective product generation were analyzed, and the possible reaction mechanisms involving photocatalytic ammonia conversion were proposed. ●OH has been identified as the main oxidant that affects the removal efficiency of ammonia nitrogen, whereas O2●- mainly affects the production of N2 and h+ is mainly responsible for the production of NO3-. These results indicate that Cu/TiO2 could be used as a low-cost and efficient photocatalyst in pretreatment process for conversion of high concentration of ammonia in wastewater.

Photocatalytic inactivation of viral particles of human norovirus by Cu-doped TiO2 non-woven fabric under UVA-LED wavelengths.

Metal-doped TiO2 photocatalysis are recognized as effective materials for eliminating human norovirus (HuNoVs). In recent years, the airborne transmission of viral particles of HuNoVs has been a cause for concern. In this study, we evaluated the virucidal effects of a Cu/TiO2 non-woven fabric (NWF) on viral particles of HuNoV genogroup II genotype 4 (HuNoV GII.4) under an ultraviolet A light-emitting diode (UVA-LED) source. For the optimized parameters, a multivariate statistical analysis using the Box-Behnken design (BBD) technique combined with the response surface methodology (RSM) was applied. The experimental results showed that the Cu/TiO2-based NWF degraded HuNoV viral particles in the air samples. The BBD-based RSM indicated that the optimum treatment conditions for inactivating the HuNoV GII.4 droplets with the Cu/TiO2 NWF were a 1:7.7 ratio of Cu:TiO2 and the use of a 373-nm UVA-LED source for 48.08 min. The optimal conditions for the photocatalytic efficacy in HuNoV GII.4 of Cu/TiO2 NWF were verified experimentally, giving a value of 2.89 ± 0.11 log10 genomic copies, which was the same as the predicted value (2.91611) within experimental uncertainty. This result adequately validated the predicted model and confirmed that viral particles of HuNoVs could efficiently be disinfected using Cu/TiO2 NWF stimulated by UVA-LED light.

Photocatalytic reduction of carbon dioxide over Cu/TiO2 photocatalysts.

The photocatalytic reduction of CO2 with H2O was investigated using Cu/TiO2 photocatalysts in aqueous solution. For this purpose, Cu/TiO2 photocatalysts (with 0.2, 0.9, 2, 4, and 6 wt.% of Cu) have been synthesized via sol-gel method. The photocatalysts were extensively characterized by means of inductively coupled plasma optical emission spectrometry (ICP-OES), N2 physisorption (BET), XRD, UV-vis DRS, FT-IR, Raman spectroscopy, TEM-EDX, and photoelectrochemical measurements. The as-prepared photocatalysts contain anatase as a major crystalline phase with a crystallite size around 13 nm. By increasing the amount of Cu, specific surface area and band gap energy decreased in addition to the formation of large agglomeration of CuO. Results revealed that the photocatalytic reduction of CO2 decreased in the presence of Cu/TiO2 in comparison to pure TiO2, which might be associated to the formation of CuO phase acting as a recombination center of generated electron-hole pair. Decreasing of photoactivity can also be connected with a very low position of conduction band of photocatalysts with high Cu content, which makes H2 production necessary for CO2 reduction more difficult.

Photocatalytic disinfection performance in virus and virus/bacteria system by Cu-TiO2 nanofibers under visible light.

The presence of pathogenic microorganisms in water is a great threat to human health, and photocatalysis is promising for disinfection. However, the research on virus inactivation with visible-light photocatalysis is still limited, especially the coexistence of virus and its host bacteria. In this study, bacteriophage f2 and its host E. coil 285 were used as the model microorganisms, and the disinfection performance of prepared Cu-TiO2 nanofibers under visible light was investigated. The result showed that the prepared Cu-TiO2 nanofibers showed a brilliant ability in terms of removing bacteriophage f2 and E. coil 285 under visible light. Series experiments indicated that the initial pH didn't affect the photocatalytic disinfection performance significantly. In the certain range, the removal efficiency of bacteriophage f2 increased with the increase of catalyst dosage, light intensity and temperature, but decreased with the increase of initial virus concentration. In virus/bacteria mixed system, bacteriophage f2 exhibited stronger resistance to photocatalytic oxidation than E. coil 285, and the removal of bacteriophage f2 was obviously affected by being mixed with E. coil 285, while the removal of E. coil 285 almost remained unchanged after being mixed with bacteriophage f2. Further research proved that competitive adsorption in mixed system played a certain role in E. coli 285 inactivation, while the free reactive oxygen species (ROSs) in the bulk phase played a crucial role in phage f2 inactivation.

Hydrogen production by tailoring the brookite and Cu2O ratio of sol-gel Cu-TiO2 photocatalysts.

Cu-TiO2 photocatalysts were prepared by the sol-gel method. Copper loadings from, 1.0 to 5.0 wt % were used. The materials were annealed at different temperatures (from 400 to 600 °C) to study the formation of brookite and copper ionic species. The photocatalysts were characterized by X-ray diffraction, UV-vis, Raman and XPS spectroscopies, H2-temperature programmed reduction (TPR), N2 physisorption, and SEM-EDS to quantify the actual copper loadings and characterize morphology. The photocatalysts were evaluated during the hydrogen photocatalytic production using an ethanolic solution (50% v/v) under UV and visible radiation. The best hydrogen production was performed by Ti-Cu 1.0 with an overall hydrogen production that was five times higher than that obtained with photolysis. This sample had an optimal thermal treatment at 500 °C, and at this temperature, the Cu2O and brookite/anatase ratio boosted the photocatalytic production of hydrogen. In addition, a deactivation test was carried out for the most active sample (TiO2-Cu 1.0), showing unchanged H2 production for three cycles with negligible Cu lixiviation. The activity of hydrogen-through-copper production reported in this research work is comparable with the one featured by noble metals and that reported in the literature for doped TiO2 materials.