Enhanced virucidal activity of facet-engineered Cu-doped TiO2 nanorods under visible light illumination.

Crystal facet engineering has emerged as a promising approach to enhance photocatalytic activity of semiconductors by preferentially accumulating charge carriers (electrons and holes) on specific facets. This facilitates efficient electron and hole transfer across the semiconductor/cocatalyst interface, enabling their transport to the cocatalyst surface for redox reactions. In this study, three Cu-doped TiO2 nanorods with small, medium, and large ratios of reductive {110} to oxidative {111} facets were synthesized (namely Cu-TiO2-SR, Cu-TiO2-MR, and Cu-TiO2-LR, respectively). These materials were comparatively evaluated for the inactivation of phiX174 bacteriophage under visible light illumination. Notably, Cu-TiO2-LR demonstrated an outstanding inactivation rate of phiX174 (0.42 log inactivation/min), approximately 11.8 times higher than that of Cu-TiO2-SR. Photo- and electrochemical analyses revealed that Cu-TiO2-LR exhibited superior electron/hole separation efficiency, leading to enhanced Cu redox reactions. Various experiments, encompassing viral inactivation tests with different additives, protein oxidation assays, and DNA damage assessments, indicated that Cu(III) is the major virucidal species responsible for the phiX174 inactivation by illuminated Cu-TiO2-LR. Under visible light illumination, Cu-TiO2-LR also showed excellent reusability and minimal activity loss in the presence of humic acid and inorganic anions, as well as general microbicidal effects on other viral and bacterial species.

Integrating machine learning with experimental investigation for optimizing photocatalytic degradation of Rhodamine B using neodymium-doped titanium dioxide: a comprehensive approach with toxicity assessment.

In this study, neodymium-doped titanium dioxide (Nd-TiO2) nanoparticles were synthesized via a hydrothermal method for the photocatalytic degradation of Rhodamine B (RhB) under UV and sunlight conditions. The properties of these NPs were comprehensively characterized. And optimization of RhB degradation was conducted using control-variable experiment and artificial neural networks (ANN) under various operational conditions and in the presence of competing compounds. The acute toxicity of both NPs, RhB, and the environmental impact of the photocatalytic treatment effluent on Danio rerio were evaluated. The Nd modification increased the catalyst's specific surface area and thermal stability. X-ray diffraction confirmed the tetragonal anatase phase in undoped TiO2, while Nd-doped TiO2 exhibited shifts in peaks and the presence of brookite and rutile phases. Nd (1 mol%) doped TiO2 demonstrated superior RhB photocatalytic degradation efficiency, achieving 95% degradation and 82% total organic carbon (TOC) removal within 60 min under UV irradiation. Optimization under sunlight conditions yielded 95.14% RhB removal with 0.28 g/L photocatalyst and 1% doping. Under UV light, 98.12% RhB removal was optimized with 0.97% doping, along with the presence of humic acid and CaCl2. ANN modeling achieved high precision (R2 of 0.99) in modeling environmental photocatalysis. Toxicity assessments indicated that the 96-h LC50 values were 681.59 mg L-1 for both NPs, and 23.02 mg L-1 for RhB. The treated dye solution exhibited a significant decline in toxicity, emphasizing the potential of 1% Nd-TiO2 in wastewater treatment.

Antibacterial Food Packaging Nanomaterial Based on Atomic Layer Deposition for Long-Term Food Storage.

The aim of the present work is to use the latest achievements of nanotechnology (atomic layer deposition, ALD) in the field of food packaging to prevent biofilm formation by food-associated bacteria. Some potential applications of nanotechnology in the food packaging industry are studied in the manuscript, in the field of antibacterial materials for food packaging. The ALD technique was used to synthesize vanadium (V)-doped TiO2 thin nanofilm on commercially available polypropylene (PP) food container to enhance an antibacterial activity for potential use in food packaging, to reduce spoilage, thereby, prolonging the food shelf- life. To better understand the ability and effectiveness of the antimicrobial packaging material of V-doped TiO2, to prevent the biofilm formation by dairy-associated pathogenic bacteria, the coated and uncoated PP containers with a fresh raw cow's milk were tested. We have illustrated the effectiveness of ALD Al2O3 + TiVOx nanocoating against populations of milk-borne pathogenic bacteria.

A handy way for forming N-doped TiO2/carbon from pectin and d,l-serine hydrazide hydrochloride.

N-doped TiO2/carbon composites (N-TiPC) have shown excellent photodegradation performances to the organic contaminants but are limited by the multistage preparation (i.e., preparation of porous carbon, preparation of N-doped TiO2, and loading of N-doped TiO2 on porous carbon). Here, we develop a handy way by combining the Pickering emulsion-gel template route and chelation reaction of polysaccharides. The N-TiPC is obtained by calcinating pectin/Dl-serine hydrazide hydrochloride (SHH)-Ti4+ chelate and is further described by modern characterization techniques. The results show that the N atom is successfully doped into the TiO2 lattice, and the bandgap value of N-TiPC is reduced to 2.3 eV. Moreover, the particle size of N-TiPC remains about 10 nm. The configurations of the composites are simulated using DFT calculation. The photocatalytic experiments show that N-TiPC has a high removal efficiency for methylene blue (MB) and oxytetracycline hydrochloride (OTC-HCL). The removal ratios of MB (20 mg/L, 50 mL) and OTC-HCL (30 mg/L, 50 mL) are 99.41 % and 78.29 %, respectively. The cyclic experiments show that the photocatalyst has good stability. Overall, this study provides a handy way to form N-TiPC with enhanced photodegradation performances. It can also be promoted to other macromolecules such as cellulose and its derivatives, sodium alginate, chitosan, lignin, etc.

Exploring structural and optical properties of iodine-doped TiO2 nanoparticles in Rhodamine-B dye degradation: Experimental and theoretical investigation.

Energy conversion and pollutant degradation are critical for advancing sustainable technologies, yet they often encounter challenges related to charge recombination and efficiency limitations. This study explores iodine-doped TiO2 nanoparticles as a potential solution for enhancing both energy conversion and pollutant degradation. The nanoparticles were synthesized via the sol-gel method with varying iodine precursor concentrations (0.025-0.1 M) and were characterized for their structural, compositional, and optical properties, particularly in relation to their photocatalytic performance in Rhodamine-B dye degradation. X-ray diffraction confirmed a tetragonal anatase crystal structure, with the average crystallite size decreasing from 10.06 nm to 8.82 nm with increase in iodine concentration. Selected area electron diffraction patterns verified the polycrystalline nature of the nanoparticles. Dynamic light scattering analysis showed hydrodynamic radii ranging from 95 to 125 nm. Fourier-transform infrared spectroscopy identified metal-oxygen vibrations at 441 cm⁻1, and electron microscopy confirmed the spherical morphology of the nanoparticles. Elemental analysis detected the presence of Ti, O, and I in the samples. Diffuse reflectance spectroscopy indicated the optical absorption edges for the doped samples in the visible region from which the corresponding band gap values were deduced. Photoluminescence spectroscopy revealed that the sample with 0.1 M iodine exhibit the lowest emission intensity, suggesting reduced charge recombination. Notably, 0.1 M iodine doped TiO2 samples demonstrated the highest photocatalytic efficiency, achieving 82.36% degradation of Rhodamine-B dye within 140 min under visible light. Additionally, ab-initio density functional theory calculations were performed to investigate the structural, optical, and adsorption properties of TiO2, iodine-doped TiO2, Rhodamine-B, and their composites, providing further insight into the enhanced photocatalytic activity observed in the experiments.

Effect of Co-Sputtered Copper and Titanium Oxide Coatings on Bacterial Resistance and Cytocompatibility of Osteoblast Cells.

One of the primary risk factors for implant failure is thought to be implant-related infections during the early healing phase. Developing coatings with cell stimulatory behaviour and bacterial adhesion control is still difficult for bone implants. This study proposes an approach for one-step deposition of biocompatible and antimicrobial Cu-doped TiO2 coatings via glow-discharge sputtering of a mosaic target. During the deposition, the bias of the Ti6Al4V substrates was changed. Structure examination, phase analysis, and surface morphology were carried out using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The hardness values and hydrophilic and corrosion performance were also evaluated together with cytocompatible and antibacterial examinations against E. coli and S. aureus. The results show great chemical and phase control of the bias identifying rutile, anatase, CuO, or ternary oxide phases. It was found that by increasing the substrate bias from 0 to -50 V the Cu content increased from 15.3 up to 20.7 at% while at a high bias of -100 V, the copper content reduced to 3 at%. Simultaneously, apart from the Cu2+ state, Cu1+ is also found in the biased samples. Compared with the bare alloy, the hardness, the water contact angle and corrosion resistance of the biased coatings increased. According to an assessment of in vitro cytocompatibility, all coatings were found to be nontoxic to MG-63 osteoblast cells over the time studied. Copper release and cell-surface interactions generated an antibacterial effect against E. coli and S. aureus strains. The -50 V biased coating combined the most successful results in inhibiting bacterial growth and eliciting the proper responses from osteoblastic cells because of its phase composition, electrochemical stability, hydrophilicity, improved substrate adhesion, and surface roughness. Using this novel surface modification approach, we achieved multifunctionality through controlled copper content and oxide phase composition in the sputtered films.

Enhanced photocatalytic performance of Bi-doped TiO2 under sunlight and UV light: mechanistic insights and comparative analysis.

Bismuth-doped metal oxides exhibit favourable photocatalytic features when exposed to both sunlight and UV light. In this approach, Bi0/TiO2 and Bi+3/TiO2 photocatalysts were prepared and their structural and optical properties are analysed using various characterization techniques. These developed photocatalysts were further tested for the photocatalytic elimination of Nitrobenzene in UV light and sunlight and compared with the performance of bare TiO2. The catalyst Bi+3/TiO2 performed better in UV light with 72.31% degradation, and 4.74 × 10-6 mol.litre-1.min-1 initial rate of reaction. However, when exposed to sunlight, Bi0/TiO2 outperformed with 73.85% degradation, and 4.63 × 10-6 mol.min-1 initial rate of reaction. This significant increase in photocatalytic activity of Bi0/TiO2 under sunlight could be accredited to increased light harvesting and enhanced efficiency in charge carrier separation, both of which were made possible by bismuth-induced surface plasmon resonance.

Aptamer molecular gate functionalized mesoporous SiO2@MB controlled-release system for pollutant detection using Ti(â ¢) self-doped TiO2 NTs as active photoanode coupled with electrostatic modulation.

Atrazine (ATZ) is a widely used herbicide that can cause serious harm to organisms and ecosystems. An immobilization-free photoelectrochemical (PEC) aptasensor has been herein developed for ATZ based on aptamer molecular gate functionalized mesoporous SiO2@MB controlled release system. Compared with traditional immobilization-based sensors, immobilization-free sensors (IFSs) avoid the modification of the recognition element on the electrode surface. Mesoporous SiO2 with large surface area and good biocompatibility can be used as nanocontainers to stably encapsulate the signal shuttle molecule methylene blue (MB). The bifunctional aptamer (APT) is used not only as the recognition element for ATZ but also as the signal switch to block or release MB. In the presence of ATZ, the specific recognition between ATZ and APT will cause the detachment of APT from the surface of SiO2, thus the molecular gate will open and release MB. Due to pH modulation, the positively charged MB can reach the surface of the negatively charged Ti(III) self-doped TiO2 NTs (Ti(III)-TiO2 NTs) electrode to act as an electron donor, which increases the photocurrent. The immobilization-free aptasensor has shown ultrasensitive detection of ATZ with a wide linear range from 1.0 pM to 100.0 nM and a low detection limit of 0.1 pM. In addition, the sensor has excellent selectivity, stability and anti-interference ability, and has been used in real water sample analysis successfully. This strategy has provided a new idea for the design of advanced immobilization-free PEC sensors for environmental pollutant detection.

Titania-zeolite composite for tetracycline photocatalytic degradation under visible light: A comparison between doping and ion exchange.

In this study, TiO2 supported over embryonic Beta zeolite (BEA) was prepared for the photocatalytic degradation of Tetracycline (TC) antibiotic under visible light. The immobilization of sol-gel TiO2 over the zeolite increased its surface area from 33 (m2/g) to 226 (m2/g) and enhanced its adsorption efficiency from 8 % to 18 %. In order to expand the photocatalytic activity of TiO2 towards the visible light region (i.e. λ > 380 nm), two different metal sensitization techniques with Iron ions from aqueous solution of FeCl3 were explored. In the ion-exchange method, the substitutional cations within the TiO2/BEA structure were exchanged with Fe3+. Whereas, in the doping technique, solgel TiO2 was doped with Fe3+ during its synthesis and before its immobilization over Zeolite. Four different samples with 20, 40, 60, and 100 % w/w of TiO2/BEA ratio were prepared. After testing the various ion-exchanged photocatalysts under blue and white lights, only Fe-60%TiO2/BEA showed better activity compared to pure TiO2 under white light at TC initial concentration, C o = 20 ppm. For the doped immobilized Titania with 60 wt% TiO2/BEA, three different doped photocatalysts were prepared with 3 %, 7 %, and 10 % per mole Fe/TiO2. All the Fe-doped TiO2/BEA photocatalysts showed better activity compared to pure TiO2 under white light. Under solar irradiations, the 3 % Fe-doped TiO2/BEA was able to degrade all TC within 120 min, while Fe-60%TiO2/BEA needed 200 min, and TiO2 needed more than 300 min. This enhanced performance was a result of both increased surface area due to immobilization over BEA as well as iron doping by Fe3+ that simultaneously increased the visible light absorption of TiO2 and minimized the charge carrier recombination effect.

Recent Advances in Metal Oxide Electron Transport Layers for Enhancing the Performance of Perovskite Solar Cells.

Perovskite solar cells (PSCs) have attracted considerable interest owing to their low processing costs and high efficiency. A crucial component of these devices is the electron transport layer (ETL), which plays a key role in extracting and transmitting light-induced electrons, modifying interfaces, and adjusting surface energy levels. This minimizes charge recombination in PSCs, a critical factor in their performance. Among the various ETL materials, titanium dioxide (TiO2) and tin dioxide (SnO2) stand out due to their excellent electron mobility, suitable band alignment, high transparency, and stability. TiO2 is widely used because of its appropriate conduction band position, easy fabrication, and favorable charge extraction properties. SnO2, on the other hand, offers higher electron mobility, better stability under UV illumination, and lower processing temperatures, making it a promising alternative. This paper summarizes the latest advancements in the research of electron transport materials, including material selection and a discussion of electron collection. Additionally, it examines doping techniques that enhance electron mobility and surface modification technologies that improve interface quality and reduce recombination. The impact of these parameters on the performance and passivation behavior of PSCs is also examined. Technological advancements in the ETL, especially those involving TiO2 and SnO2, are currently a prominent research direction for achieving high-efficiency PSCs. This review covers the current state and future directions in ETL research for PSCs, highlighting the crucial role of TiO2 and SnO2 in enhancing device performance.

N-doped TiO2/rGO: synthesis, structure, optical characteristics, and humidity sensing applications.

In the current study, the effect of rGO ratio on the N-dopped TiO2has been synthesized through sol-gel method. The prepared N-doped TiO2/rGO composites were examined for humidity sensing applications. The relationship between optical properties and the humidity sensing properties was studied. The structure, morphology, and bonding interaction have been examined using XRD, FT-IR, PL and HRTEM respectively. The average particle size as estimated from XRD and HRTEM was found to be about 9 nm. The optical properties have been studied using UV/ Vis. Spectroscopy. Further, optical parameters including refractive index and optical band gap energy have been estimated. The humidity sensing behavior of the resultant composites were evaluated in a wide range of humidity (7%-97% RH) at different testing frequencies. The optical band gap was found to be decreased as the amount of rGO increase. Among all prepared samples, both the optical parameters and humidity sensing experiments confirmed that the 0.5% rGO@N-dopped TiO2sample is the best candidate for the humidity sensing applications. The best optimum testing frequency was demonstrated to be 50 Hz. The sensor demonstrates a fast response and recovery times of 13 s and 33 s with low hysteresis and large sensitivity. The humidity sensing mechanism was studied using complex impedance spectroscopy at different RH levels under testing frequency range from 50 Hz to 5 MHz and testing voltage of 1 VAC. The produced structure demonstrated a promising material for humidity measuring devices.

Direct Photocatalytic Methane Oxidation to Formaldehyde by N Doping Co-Decorated Mixed Crystal TiO2.

In this paper, N-doped TiO2 mixed crystals are prepared via direct calcination of TiN for highly selective oxidation of CH4 to HCHO at room temperature. The structures of the prepared TiO2 samples are characterized to be N-doped TiO2 of anatase and rutile mixed crystals. The crystal structures of TiO2 samples are determined by XRD spectra and Raman spectra, while N doping is demonstrated by TEM mapping, ONH inorganic element analysis, and high-resolution XPS results. Significantly, the production rate of HCHO is as high as 23.5 mmol·g-1·h-1 with a selectivity over 90%. Mechanism studies reveal that H2O is the main oxygen source and acts through the formation of ·OH. DFT calculations indicate that the construction of a mixed crystal structure and N-doping modification mainly act by increasing the adsorption capacity of H2O. An efficient photocatalyst was prepared by us to convert CH4 to HCHO with high yield and selectivity, greatly promoting the development of the photocatalytic CH4 conversion study.

Changeable Active Sites by Pr Doping CuSA-TiO2 Photocatalyst for Excellent Hydrogen Production.

Photocatalytic water splitting for clean hydrogen production has been a very attractive research field for decades. However, the insightful understanding of the actual active sites and their impact on catalytic performance is still ambiguous. Herein, a Pr-doped TiO2-supported Cu single atom (SA) photocatalyst is successfully synthesized (noted as Cu/Pr-TiO2). It is found that Pr dopants passivate the formation of oxygen vacancies, promoting the density of photogenerated electrons on the CuSAs, and optimizing the electronic structure and H* adsorption behavior on the CuSA active sites. The photocatalytic hydrogen evolution rate of the obtained Cu/Pr-TiO2 catalyst reaches 32.88 mmol g-1 h-1, 2.3 times higher than the Cu/TiO2. Innovatively, the excellent catalytic activity and performance is attributed to the active sites change from O atoms to CuSAs after Pr doping is found. This work provides new insight for understanding the accurate roles of single atoms in photocatalytic water splitting.

Pd:In-Doped TiO2 as a Bifunctional Catalyst for the Photoelectrochemical Oxidation of Paracetamol and Simultaneous Green Hydrogen Production.

The integration of clean energy generation with wastewater treatment holds promise for addressing both environmental and energy concerns. Focusing on photocatalytic hydrogen production and wastewater treatment, this study introduces PdIn/TiO2 catalysts for the simultaneous removal of the pharmaceutical contaminant paracetamol (PTM) and hydrogen production. Physicochemical characterization showed a high distribution of Pd and In on the support as well as a high interaction with it. The Pd and In deposition enhance the light absorption capability and significantly improve the hydrogen evolution reaction (HER) in the absence and presence of paracetamol compared to TiO2. On the other hand, the photoelectroxidation of PTM at TiO2 and PdIn/TiO2 follows the full mineralization path and, accordingly, is limited by the adsorption of intermediate species on the electrode surface. Thus, PdIn-doped TiO2 stands out as a promising photoelectrocatalyst, showcasing enhanced physicochemical properties and superior photoelectrocatalytic performance. This underscores its potential for both environmental remediation and sustainable hydrogen production.

Study on the Sodium-Doped Titania Interface-Type Memristor.

Memristors integrated into a crossbar-array architecture (CAA) are promising candidates for analog in-memory computing accelerators. However, the relatively low reliability of the memristor device and sneak current issues in CAA remain the main obstacles. Alkali ion-based interface-type memristors are promising solutions for implementing highly reliable memristor devices and neuromorphic hardware. This interface-type device benefits from self-rectifying and forming-free resistive switching (RS), and exhibits relatively low variation from device to device and cycle to cycle. In a previous report, we introduced an in situ grown Na/TiO2 memristor using atomic layer deposition (ALD) and proposed a RS mechanism from experimentally measured Schottky barrier modulation. Self-rectifying RS characteristics were observed by the asymmetric distribution of Na dopants and oxygen vacancies as the Ti metal used as the adhesion layer for the bottom electrode diffuses over the Pt electrode at 250 °C during the ALD process and is doped into the TiO2 layer. Here, we theoretically verify the modulation of the Schottky barrier at the TiO2/Pt electrode interface by Na ions. This study fabricated a Pt/Na/TiO2/Pt memristor device and confirmed its self-rectifying RS characteristics and stable retention characteristics for 24 h at 85 °C. Additionally, this device exhibited relative standard deviations of 27 and 7% in the high and low resistance states, respectively, in terms of cycle-to-cycle variation. To verify the RS mechanism, we conducted density functional theory simulations to analyze the impact of Na cations at interstitial sites on the Schottky barrier. Our findings can contribute to both fundamental understanding and the design of high-performance memristor devices for neuromorphic computing.

Ce-Doped TiO2 Fabricated Glassy Carbon Electrode for Efficient Hydrogen Evolution Reaction in Acidic Medium.

The quest for sustainable and clean energy sources has intensified research on the Hydrogen Evolution Reaction (HER) in recent decades. In this study, we have presented a novel Ce-doped TiO2 catalyst synthesized through the sol-gel method, showcasing its potential as a superior electrocatalyst for HER in an acidic medium. Comprehensive characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Energy dispersive X-ray (EDX), and Raman spectroscopy confirms the successful formation of the catalyst. Electrocatalytic performance evaluation, including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and Tafel analysis, demonstrates that GCE-5wt.%CeTiO2 outperforms bare GCE, as well as Ce and TiO2-based electrodes. Kinetic investigations reveal a Tafel slope of 105 mV dec-1, indicating the Volmer step as the rate-determining step. The onset potential for HER at GCE-5wt.%CeTiO2 is -0.16 V vs. RHE, close to the platinum electrode. Notably, the catalyst exhibits a low overpotential of 401 mV to achieve a current density of 10 mA cm-2 with an impressive 95 % Faradaic efficiency. Furthermore, the catalyst demonstrates outstanding durability, maintaining a negligible increase in overpotential during a 14-hour chronoamperometry test. These results have far-reaching implications for the development of cost-effective and efficient electrocatalysts for hydrogen production.

Multiscale Interface Engineering of Sulfur-Doped TiO2 Anode for Ultrafast and Robust Sodium Storage.

Sodium-ion batteries (SIBs) are a promising electrochemical energy storage system; however, their practical application is hindered by the sluggish kinetics and interfacial instability of anode-active materials. Here, to circumvent these issues, we proposed the multiscale interface engineering of S-doped TiO2 electrodes with minor sulfur/carbon inlaying (S/C@sTiO2), where the electrode-electrolyte interface (SEI) and electrode-current collector interface (ECI) are tuned to improve the Na-storage performance. It is found that the S dopant greatly promotes the Na+ diffusion kinetics. Moreover, the ether electrolyte generates much less NaF in the cycled electrode, but relatively richer NaF in the SEI in comparison to fluoroethylene carbonate-contained ester electrolyte, leading to a thin (9 nm), stable, and kinetically favorable SEI film. More importantly, the minor sodium polysulfide intermediates chemically interact with the Cu current collector to form a Cu2S interface between the electrode and the Cu foil. The conductive tree root-like Cu2S ECI serves not only as active sites to boost the specific capacity but also as a 3D "second current collector" to reinforce the electrode and improve the Na+ reaction kinetics. The synergy of S-doping and optimized SEI and ECI realizes large specific capacity (464.4 mAh g-1 at 0.1 A g-1), ultrahigh rate capability (305.8 mAh g-1 at 50 A g-1), and ultrastable cycling performance (91.5% capacity retention after 3000 cycles at 5 A g-1). To the best of our knowledge, the overall SIB performances of S/C@sTiO2 are the best among all of the TiO2-based electrodes.

Effect of chromium doping on the band gap tuning of titanium dioxide thin films for solar cell applications.

A simple and inexpensive spray pyrolysis deposition (SPD) approach was used to produce TiO2 and Cr (2-8) at.%-doped TiO2 thin films. To explore the morphological features of the films, FE-SEM micrographs were used and found that 6 and 8 at.% TiO2:Cr films had fibrous patterns with diameters of 0.45 and 0.78 µm, respectively, while the remainder of the films were agglomerated particles. From X-ray diffraction investigation, it was found that the TiO2 thin films had an anatase crystal phase (tetragonal) up to 6 at.% Cr doping, while an anatase-rutile mixed crystalline phase was identified for 8 at.% Cr doping. The crystallite size of the pristine TiO2 film was 35 nm, while for TiO2:Cr films, it ranges from 35 to 46 nm. The Fizeau fringes technique was employed to measure the thickness of the TiO2 film and 165 nm was found for pristine TiO2 and 164-180 nm for TiO2:Cr films. UV-visible spectroscopy was used to study optical properties such as absorbance, refractive index, optical band gap, dielectric constant, and optical conductivity. As the Cr concentration increases, the optical band gap decreases from 3.40 eV to 2.70 eV. Using the four-point probe method, it was found that the resistivity changes with temperature and is also affected by the Cr content.

Virucidal activity of Cu-doped TiO2 nanoparticles under visible light illumination: Effect of Cu oxidation state.

Copper (Cu) is an effective antimicrobial material; however, its activity is inhibited by oxidation. Titanium dioxide (TiO2) photocatalysis prevents Cu oxidation and improves its antimicrobial activity and stability. In this study, the virucidal efficacy of Cu-doped TiO2 nanoparticles (Cu-TiO2) with three different oxidation states of the Cu dopant (i.e., zero-valent Cu (Cu0), cuprous (CuI), and cupric (CuII) oxides) was evaluated for the phiX174 bacteriophage under visible light illumination (Vis/Cu-TiO2). CuI-TiO2 exhibited superior virucidal activity (5 log inactivation in 30 min) and reusability (only 11 % loss of activity in the fifth cycle) compared to Cu0-TiO2 and CuII-TiO2. Photoluminescence spectroscopy and photocurrent measurements showed that CuI-TiO2 exhibited the highest charge separation efficiency and photocurrent density (approximately 0.24 µA/cm2) among the three materials, resulting in the most active redox reactions of Cu. Viral inactivation tests under different additives and viral particle integrity analyses (i.e., protein oxidation and DNA damage analyses) revealed that different virucidal species played key roles in the three Vis/Cu-TiO2 systems; Cu(III) was responsible for the viral inactivation by Vis/CuI-TiO2. The Vis/CuI-TiO2 system exhibited substantial virucidal performance for different viral species and in different water matrices, demonstrating its potential practical applications. The findings of this study offer valuable insights into the design of effective and sustainable antiviral photocatalysts for disinfection.

Graphite/carbon-doped TiO2 nanocomposite synthesized by ultrasound for the degradation of diclofenac.

Graphite/C-doped TiO2 nanocomposite was synthesized at room temperature using a simple, impressive, and indirect sonication (20 kHz) by the cup horn system. Tetrabutyltitanate as the precursor of titanium and graphite (G) as the carbon source was used in the preparation of nanocomposite as a photocatalyst. The molar ratio of G/TiO2 as a key parameter was investigated in the synthesis of G/C-doped TiO2. The obtained materials were widely characterized using XRD, SEM, TEM, FTIR, XPS, and UV-Vis diffuse reflectance techniques. The UV-Vis diffuse reflectance spectroscopy results showed that the edge of light absorption of nanocomposite was distinctly red-shifted to the visible area via carbon doping. The XPS outcomes acknowledged the existence of the C, Ti, and O in the photocatalyst. The composite showed an enhancement in the dissociation efficiency of photoinduced charge carriers through the doping process. The photocatalytic activity of the synthesized nanocomposite was checked with diclofenac (DCF) as a pharmaceutical contaminant. The results displayed that G/C-doped TiO2 represented better photocatalytic performance for DCF than TiO2. This was due to the excellent crystallization, intense absorption of visible light, and the impressive separation of photoinduced charge carriers. Various active species such as •OH, •O2¯, h+, and H2O2 play a role in the degradation of DFC. Therefore, different scavengers were used and the role of each one in degradation was investigated. According to the obtained results, •O2¯ radical showed a major role in the photocatalytic process. This work not only proposes a deep insight into the photosensitization-like mechanism by using G-based materials but also develops new photocatalysts for the removal of emerging organic pollutants from waters using sunlight as available cheap energy.