Cu-doped TiO2 Research Articles

Copper-/Zinc-Doped TiO2 Nanopowders Synthesized by Microwave-Assisted Sol–Gel Method

Using the microwave-assisted sol-gel method, Zn- and Cu-doped TiO2 nanoparticles with an anatase crystalline structure were prepared. Titanium (IV) butoxide was used as a TiO2 precursor, with parental alcohol as a solvent and ammonia water as a catalyst. Based on the TG/DTA results, the powders were thermally treated at 500 °C. XRD and XRF revealed the presence of a single-phase anatase and dopants in the thermally treated nanoparticles. The surface of the nanoparticles and the oxidation states of the elements were studied using XPS, which confirmed the presence of Ti, O, Zn, and Cu. The photocatalytic activity of the doped TiO2 nanopowders was tested for the degradation of methyl-orange (MO) dye. The results indicate that Cu doping increases the photoactivity of TiO2 in the visible-light range by narrowing the band-gap energy.

Selective Oxidation of Cyclohexane to Cyclohexanol/Cyclohexanone by Surface Peroxo Species on Cu-Mesoporous TiO2.

Selective oxidation of cyclohexane to cyclohexanol/cyclohexanone (KA-oil) is an important chemical process, which is still constrained by low conversion and selectivity and high energy consumption. In this study, Cu-doped mesoporous TiO2 (Cu-MT) has been successfully synthesized via calcinating MIL-125(Ti) doped with copper acetylacetonate, which shows high reactivity in selective oxidation of cyclohexane to KA-oil by persulfate (PS) with the desirable cyclohexane conversion of 16.8% and a selectivity of 98.0% under mild conditions and the low ratio of PS/cyclohexane of 1:1. A series of characterizations and density functional theory calculations reveal that the doped Cu(I,II) on Cu-MT is the reactive site for non-radical activation of PS with the moderate elongation of the O-O bond in PS, which then abstracts 1H (1H+ + 1e-) from cyclohexane to form Cy• and eventually KA-oil. This study gives new insight on the importance of moderately activated PS in selective oxidation of C-H.

Cu-doped TiO2 nanoparticles improve local antitumor immune activation and optimize dendritic cell vaccine strategies

Nanoparticle-mediated cancer immunotherapy holds great promise, but more efforts are needed to obtain nanoformulations that result in a full scale activation of innate and adaptive immune components that specifically target the tumors. We generated a series of copper-doped TiO2 nanoparticles in order to tune the kinetics and full extent of Cu2+ ion release from the remnant TiO2 nanocrystals. Fine-tuning nanoparticle properties resulted in a formulation of 33% Cu-doped TiO2 which enabled short-lived hyperactivation of dendritic cells and hereby promoted immunotherapy. The nanoparticles result in highly efficient activation of dendritic cells ex vivo, which upon transplantation in tumor bearing mice, exceeded the therapeutic outcomes obtained with classically stimulated dendritic cells. Efficacious but simple nanomaterials that can promote dendritic cancer cell vaccination strategies open up new avenues for improved immunotherapy and human health.Graphical

Efficient photocatalysis of Cu doped TiO2/g-C3N4 for the photodegradation of methylene blue

The release of dyes into normal water reservoirs has become a tremendous environmental problem and the development of methods to remove such dyes is essential. A novel photocatalyst was fabricated in which Cu doped to TiO2 was coupled with g-C3N4 (Cu-TiO2/g-C3N4) in different weight percentages as 10, 30 and 50%, hydrothermally. Pure TiO2 consisted of both Anatase and Rutile phases where slight lattice distortions were observed in the Cu-doped TiO2 as evidenced by the XRD and Raman analysis. Cu was present at 1.7% by weight respective to TiO2 according to the XRF analysis. Spherical and irregularly shaped aggregated Cu-doped TiO2 nanoparticles in the range of 15–55 nm were heterogeneously distributed on the g-C3N4 matrix as observed by TEM and SEM. The band gap of TiO2 (3.0 eV) was reduced to 2.67 upon doping with Cu. The band gap of g-C3N4 was found to be 2.81 eV and that of Cu-TiO2/g-C3N4 in different weight percentages were in the range of 2.82 to 2.88 eV. Synthesized photocatalysts were tested on the ability to degrade methylene blue under UV and Visible light. Cu-TiO2/50% g-C3N4 showed the highest rate constant (4.4 × 10-3 min−1) which is 5 and 9.8 times greater than TiO2 and g-C3N4, respectively. The rate constant decreased with the introduction of EDTA and Isopropyl alcohol as they scavenge holes and hydroxyl radicals, respectively. The photocatalytic activity of all the nanomaterials increased with the increasing concentration of persulfate due to the increasing concentration of SO4●- and OH● produced. Synthesized nanomaterials effectively adsorb methylene blue under dark conditions following the pseudo-second-order kinetics suggesting that methylene blue molecules were chemisorbed to the adsorbents. The adsorption rate constant resulting in the best-performing photocatalyst was 0.122 g mg−1 min−1. Hence, it is evident that Cu-TiO2/g-C3N4 can effectively degrade methylene blue.

Synthesis of Cu-Doped TiO2 on Wood Substrate with Highly Efficient Photocatalytic Performance and Outstanding Recyclability for Formaldehyde Degradation.

Photocatalytic oxidation is considered one of the most effective ways to remove formaldehyde from indoor air. However, the use of powder photocatalysts is limited by their low adsorption capacity and strong aggregation tendency. Hence, there is a need for a composite material with good cycling stability and high degradation efficiency. In the present study, a unique wood-based composite is produced by arranging Cu-TiO2 nanoparticles on porous structured wood. The porous structure of wood can adsorb formaldehyde, and the abundant functional groups on the surface can act as a reaction platform for anchoring the Cu-TiO2 nanoparticles. Cu doping facilitates electron interaction between TiO2 and Cu, promotes the transfer of charge carriers, lowers the electron-hole recombination rate, and improves the photocatalytic degradation efficiency of formaldehyde. The photocatalytic efficiency of the wood-based composites was highest (85.59%) when the n(Cu)/n(Ti) ratio was 7%. After nine cycles, the wood composites still had a high degradation rate, indicating good recyclability. Overall, this wood composite is an eco-friendly and promising material for indoor air filtration.

Low-Temperature Synthesis of Cu-Doped Anatase TiO2 Nanostructures via Liquid Phase Deposition Method for Enhanced Photocatalysis.

Titanium dioxide (TiO2) photocatalysis can harness the energy from sunlight, providing a solution to many green- and energy-related problems. In this study, we aimed to produce Cu doped TiO2 (Cu-TiO2) structures at a low temperature (~70 °C) under atmospheric pressure based on liquid phase deposition. The products prepared with Cu nitrate exhibited anatase-phase TiO2 with the presence of Cu, and the particles showed a waxberry-like structure. Changing the Cu nitrate concentration allowed control of the atomic concentration; we confirmed ~1.3 atm.% of Cu ions in the product when we applied 10 mM in the precursor solution. By doping Cu, the light absorption edge shifted to 440 nm (~2.9 eV), and we proved the photocatalytic reaction through action spectral measurement. We observed the decomposition of acetaldehyde into CO2 on Cu-TiO2 photocatalysts, which produced optimized improvements in photocatalytic activity at Cu dopant levels between 0.2 and 0.4 atm.%. This study demonstrates that the liquid phase deposition technique can be used for doping metallic ions into TiO2, which shows promise for preparing novel and unique nanomaterials as visible light photocatalysts.

Sonocatalytic Degradation of Tetracycline with Cu-Doped TiO2 Nanoparticles as the Catalyst: Optimization, Kinetics, and Mechanism

Sonocatalytic Degradation of Tetracycline with Cu-Doped TiO2 Nanoparticles as the Catalyst: Optimization, Kinetics, and Mechanism

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%.

Label-Free Myoglobin Biosensor Based on Pure and Copper-Doped Titanium Dioxide Nanomaterials.

In this study, using pure and copper-doped titanium dioxide (Cu-TiO2) nanostructures as the base matrix, enzyme-less label free myoglobin detection to identify acute myocardial infarction was performed and presented. The Cu-TiO2 nanomaterials were prepared using facile sol-gel method. In order to comprehend the morphologies, compositions, structural, optical, and electrochemical characteristics, the pure and Cu-TiO2 nanomaterials were investigated by several techniques which clearly revealed good crystallinity and high purity. To fabricate the enzyme-less label free biosensor, thick films of synthesized nanomaterials were applied to the surface of a pre-fabricated gold screen-printed electrode (Au-SPE), which serves as a working electrode to construct the myoglobin (Mb) biosensors. The interference study of the fabricated biosensor was also carried out with human serum albumin (HSA) and cytochrome c (cyt-c). Interestingly, the Cu-doped TiO2 nanomaterial-based Mb biosensor displayed a higher sensitivity of 61.51 µAcm-2/nM and a lower detection limit of 14 pM with a response time of less than 10 ms.

First-principles DFT study of structural, electronic and optical properties of Cu-doped TiO[formula omitted] (112) surface for enhanced visible-light photocatalysis

In this work, first-principles density functional theory (DFT) calculations are used to study the structural, electronic, and optical properties of pristine and Cu-doped TiO2 (112) surface in oxygen-rich environment, and then compare the results to the bulk phase. We find the pristine (112) surface to be chemically and thermodynamically stable, exhibiting indirect band gap value of 2.89 eV. By 5.6% concentration of Cu-doping, the energy gap in the asymmetric spin bands and PDOS reaches a value of 2.00 eV, with induced magnetism. The visible range direct band gap in Cu-doped systems enhances the photo-absorption triggering the threshold value and the inter-band transitions by lowering the intensity of the dielectric constant, reflectance, and refractive index, making them suitable candidates for optoelectronics and photocatalytic applications.

Structural, optical and electronic properties of copper doped TiO2: Combined experimental and DFT study

• Electronic properties of TiO 2 with the low doping concentration of Cu has been calculated. • The microstructures of the Cu-TiO 2 nanoparticles deposited on film. In this paper, we demonstrate that the low Cu doping concentration modifies electronic properties of TiO 2 through experimental and computational studies (Density Functional theory-DFT). Cu-to-TiO 2 thin films with different Cu wt% were prepared by electrostatic spray pyrolysis method. The effect of Cu doping on TiO 2 were analyzed using various characterizations such as X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman spectroscopy, and scanning electron microscopy. The XRD reveals that the Cu-doped TiO 2 crystallizes in a tetragonal structure with an anatase phase. Raman spectroscopy confirmed the presence of strong chemical bonds and functional groups at the TiO 2 interface. UV-Vis spectroscopy was used to record the optical characteristics of doped and undoped samples. Uv-Vis spectroscopy revealed a reduction in band gap after doping. Surface morphology of the Cu-doped TiO 2 thin films were analysis using SEM. SEM images revealed no significant changes in particle size or microstructures of the synthesized materials. Additionally, DFT modelling was carried out to confirm the effects of dopants on electronic properties of the thin film. The results were analyzed, and the experimental results were corroborated, by the analysis.

Colloidal Cu-doped TiO2 nanocrystals containing oxygen vacancies for highly-efficient photocatalytic degradation of benzene and antibacterial

Development of suitable colloidal photocatalysts with excellent photocatalytic performance under visible light is essential for indoor environmental remediation. In this study, colloidal Cu-doped TiO2 (Cu-TiO2) nanocrystals containing oxygen vacancies (OVs) were synthesized by a facile sol-hydrothermal method and their photocatalytic performances for benzene degradation and antibacterial were investigated. Characterization results revealed that the doping of Cu induced grain size reduction and bandgap narrowing of TiO2 nanocrystals, as well as the formation of abundant OVs in the TiO2 crystal structure, resulting in enhanced light absorption capacity and charge carrier separation efficiency. The optimized colloidal Cu-TiO2 nanocrystals could achieve a maximum degradation rate constant of 0.364 h−1 for the photocatalytic degradation of benzene and a high antibacterial rate of more than 99.99% against both Escherichia coli and Staphylococcus aureus, which were far superior to those of the pristine TiO2. The effects of Cu dopants and OVs on the band structure of TiO2 were revealed by density functional theory (DFT) calculations combined with experimental characterizations, and a possible mechanism for the enhancement of Cu-TiO2 photocatalytic performance was proposed. This work offers a promising method for the synthesis of colloidal TiO2-based nanocrystals with excellent photocatalytic performances for the practical application in indoor environmental remediation.

Multi-Functional Materials Based on Cu-Doped TiO2 Ceramic Fibers with Enhanced Pseudocapacitive Performances and Their Dielectric Characteristics.

In this work, pure TiO2 and Cu (0.5, 1, 2%)-doped TiO2 composites prepared by electrospinning technique followed by calcination at 900 °C, and having high pseudocapacitive and dielectric characteristics were reported. These nanocomposites were characterized by scanning electron microscopy, X-ray diffraction, and dynamic water sorption vapor measurements. The structural characterization of these nanostructures highlighted good crystallinity including only the rutile phase. The electrochemical characteristics were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements, which were performed in a KOH electrolyte solution. Among the Cu-doped TiO2 nanostructures that were prepared, the one containing 0.5% Cu exhibited superior electrochemical properties, including high specific gravimetric capacitance of 1183 F·g-1, specific capacitance of 664 F·g-1, energy density of 45.20 Wh·kg-1, high power density of 723.14 W·kg-1, and capacitance retention of about 94% after 100 cycles. The dielectric investigation shows good dielectric properties for all materials, where the dielectric constant and the dielectric loss decreased with the frequency increase. Thus, all the interconnected studies proved that these new materials show manifold ability and real applicative potential as pseudocapacitors and high-performance dielectrics. Future work and perspectives are anticipated for characterizing electrochemical and dielectric properties for materials including larger amounts of Cu dopant.

Synthesis of Cu-Doped TiO2 Nanocatalyst for the Enhanced Photocatalytic Degradation and Mineralization of Gabapentin under UVA/LED Irradiation: Characterization and Photocatalytic Activity

Light-harvesting of titanium oxide (TiO2) was enhanced by copper (Cu) doping, and its performance was evaluated by gabapentin (GBP) degradation under UVA-LED irradiation. The morphology and structure of TiO2 and Cu-TiO2 were characterized using XRD, FTIR, FE-SEM, EDX, TEM, PL, DRS, and BET analysis. The complete degradation of 10 mg/L GBP was obtained in the developed photocatalytic process under the optimal conditions: catalyst loading, 0.4 g/L; pH solution, 8; and reaction time, 20 min. The reactive species trapping was studied to identify the degradation mechanism in this system. Among the water matrix experiments, phosphate (PO43−) anion indicated an inverse effect in increasing efficiency. Finally, the main intermediates generation during the GBP degradation was investigated based on LC-MS analysis, and a decomposition pathway was proposed. Accordingly, doping TiO2 with Cu resulted in the development of a UVA-activated photocatalyst for efficiently degrading and mineralizing GBP as a model of a pharmaceutical compound.

Fabrication of noble-metal-free copper-doped TiO2 nanofibers synergized with acetic acid-treated g-C3N4 nanosheets for enhanced photocatalytic hydrogen evolution

The combination of copper-doped TiO2 nanofibers (Cu-TiO2 NFs) with acetic acid-treated graphitic carbon nitride (g-C3N4) provided an efficient photocatalyst for hydrogen (H2) evolution. Nanosheets of g-C3N4 (0.2, 0.3, and 0.4 wt%) integrated with Cu-doped TiO2 NFs displayed improved photocatalytic H2 evolution efficiency. The highest H2 evolution of 1.30 mmol/g was recorded for 0.3 wt% g-C3N4 coated on Cu-TiO2 NFs, which was 18.64-fold higher than the H2 evolution of g-C3N4 alone and 8.15-fold higher than the H2 evolution of pure TiO2 NFs. As indicated by different experimental characterizations, the incorporation of photosensitizers, including copper and g-C3N4 nanosheets, enabled enhanced photoresponse and successful separation of charge carriers. Furthermore, the synergistic effect between 1D and 2D structures resulted in heterojunction formation which helped in superior charge separation consequently enhancing photocatalytic H2 evolution. Thus, this work can provide new ideas and insights for the synthesis of non-precious metal-based photocatalysts.

Characterization and photocatalytic performance of hydrothermally synthesized Cu-doped TiO2 NPs

Titanium dioxide (TiO2) nanoparticles having different Cu doping concentration (0, 2.5 and 5%) are synthesized using simple hydrothermal processing. Copper doping effect in TiO2 matrix is investigated through different complimentary analytical techniques. XRD and Raman confirm the anatase phase of TiO2. TEM and XRD depict that particle size is altered with doping without any change in morphology. UV–Vis study reveals decrement in the band gap of TiO2 NPs on introducing Cu content. Photoluminescence shows emission peaks that are red shifted and arise due to oxygen and titanium vacancies appearing after Cu2+ ions doping. The photo-induced catalytic behaviour of Cu-doped TiO2 NPs is estimated through decomposition of methylene blue dye solution. The results depict that Cu2+ ions incorporation in TiO2 NPs lead to higher catalytic activity. The present work established that Cu-doped TiO2 NPs are promising materials employable as photocatalysts for various environmental applications.

Evaluation of antibacterial property and biocompatibility of Cu doped TiO2 coated implant prepared by micro-arc oxidation.

In order to enhance osteogenic differentiation and antibacterial property of dental implants, volcano-shaped microporous TiO2 coatings doped with Cu were fabricated via micro-arc oxidation (MAO) on Ti. Cu-doped coating with different mass ratios of Cu were obtained by changing the concentration of copper acetate in the electrolyte. The structure of Cu-TiO2 coatings were systematically investigated. Element Copper was uniformly distributed throughout the coating. Compared with TiO2 coating, the Cu-doped can further improved proliferation of bone mesenchymal stem cells (BMSCs), facilitated osteogenic differentiation. The bacteriostasis experiments demonstrated that Cu-doped TiO2 coating possess excellent antibacterial property against Staphylococcus aureus (S. aureus) and Porphyromonas gingivalis (P. gingivalis).

Hybrid Density Functional Investigation of Cu Doping Impact on the Electronic Structures and Optical Characteristics of TiO2 for Improved Visible Light Absorption.

We report a theoretical investigation of the influence of Cu doping into TiO2 with various concentrations on crystal structure, stability, electronic structures and optical absorption coefficient using density functional theory via the hybrid formalism based on Heyd Scuseria Ernzerhof. Our findings show that oxygen-rich environments are better for fabricating Cu-doped materials and that the energy of formation for Cu doping at the Ti site is lower than for Cu doping at the O site under these environments. It is found that Cu doping introduces intermediate bands into TiO2, narrowing the band gap. Optical absorption curves show that the Cu-doped TiO2 can successfully harvest visible light. The presence of widely intermediate bands above the valence-band edge could explain the increase in the visible light absorption range. However, the intensity of visible light absorption rises with the increase in doping concentration.

Impact of Cu on structural, optical, dielectric properties and antibacterial activity of TiO2 thin films

In this work, Copper-doped TiO2 thin films were synthesized on glass substrates using a sol-gel dip-coating technique with varied molar concentrations of copper precursor (1,3,5,7,9 at. wt. %). Cu affected the structural, morphological, dielectric, antibacterial, and optical properties of TiO2 films. The formation of the anatase phase was confirmed by XRD. The morphology of all synthesized thin films was spherical grains with slight aggregation. The hopping process explained dielectric characteristics that obeyed the Maxwell-Wagner model and Koop's theory. These films were ideal for high-frequency devices because of their low dielectric constant. It was observed that as Cu concentration increased, the optical band gap energy reduced, which was beneficial for improving solar cell efficiency. Cu-doped TiO2 produced the best antibacterial agent. The photocatalysts with the highest photo activities were those containing 9 wt% Cu. The increased light absorption in the UV-VIS range and the lower recombination rate of the photoinduced electron hole pair of Cu-doped TiO2 thin films were responsible for the improved photocatalytic activity. Methylene blue degraded in the presence of sunshine, making it a potential material for the treatment of water.

Fabrication and characterization of Ag- and Cu-doped TiO2 nanotubes (NTs) by in situ anodization method as an efficient photocatalyst

Fabrication and characterization of Ag- and Cu-doped TiO2 nanotubes (NTs) by in situ anodization method as an efficient photocatalyst