CuO TiO2 Research Articles

H2O2-assisted photo-electrocatalytic and photocatalytic degradation of methyl violet by CuO-modified TiO2 nanotube arrays

Photoelectrocatalytic degradation is an environmental friendly and efficient technique providing solutions for the dire issue of water pollution. TiO2 nanotubes are widely used as the photocatalyst but its efficiency is restricted by the wide band gap. This study deals with the fabrication of CuO-modified TiO2 nanotubes by electrochemical anodization following the hydrothermal method to enhance the photocatalytic degradation. Optical studies revealed a reduction in the bandgap (2.12 eV) of CuO-modified TiO2 nanotubes, which plays an important role in increasing the photocatalytic activity. The effect of CuO loading on TiO2 nanotubes in photocatalytic degradation as well as the effect of bias and H2O2 on photo-electrocatalytic degradation were studied. In photocatalytic degradation, 0.05 M CuO–TiO2 photocatalyst produced a maximum degradation of 49.5 % in 8 h. Compared with the pristine TiO2 nanotubes, the photodegradation of CuO-loaded TiO2 nanotubes increased by 16 %. Furthermore, when an external bias was applied, the photodegradation efficiency increased by 36 %. In addition of H2O2 to the PEC system, 0.05 CuO–TiO2 photocatalyst produced 100 % degradation of methyl violet in 2.5 h. Reusability studies showed that the photocatalysts are stable and can therefore be used for practical applications such as photocatalytic degradation and photoelectrochemical degradation of methyl violet.

Adsorption of CO and SO2 on SnS monolayer doped with transition metal oxides (TiO2, CuO, and NiO): A DFT study

Industrial emissions, particularly CO and SO2, pose significant threats to both the ecological environment and human health, highlighting the critical need for online monitoring and the removal of these harmful gases. Based on density functional theory, this study explores the adsorption mechanisms of CO and SO2 on SnS monolayer doped with transition metal oxides (TiO2, CuO and NiO), analyzing geometric structures, band structures, state densities, work functions, and molecular orbitals. The findings reveal that transition metal oxides significantly alter the surface activity of SnS, with TiO2 doping and CuO doping reducing the band gap by 9.37% and 39.05%, respectively, and NiO doping increasing the band gap by 4.60%. CuO-SnS and NiO-SnS demonstrate robust physicochemical adsorption capabilities for CO and SO2, while TiO2-SnS displays certain physical adsorption properties. Following the adsorption of SO2, CuO-SnS and NiO-SnS exhibit the most significant changes in work function, increasing by 18.37% and 7.55%, respectively. The adsorption of CO and SO2 significantly alters the LUMO and HOMO levels, as indicated by molecular orbital analysis, suggesting that the changes in electrical conductivity post-adsorption facilitate accurate differentiation of gas types. The findings indicate that SnS doped with transition metal oxides (TiO2, CuO and NiO) hold potential as gas-sensitive sensing materials suitable for the online monitoring of CO and SO2.

Persulfate assisted photocatalytic and antibacterial activity of TiO2–CuO coupled with graphene oxide and reduced graphene oxide

Photocatalysts of TiO2–CuO coupled with 30% graphene oxide (GO) were hydrothermally fabricated, which varied the TiO2 to CuO weight ratios to 1:4, 1:2, 1:1, 2:1 and 4:1 and reduced to form TiO2–CuO/reduced graphene oxide (rGO) photocatalysts. They were characterized using XRD, TEM, SEM, XPS, Raman, and DRS technologies. TiO2–CuO composites and TiO2–CuO/GO degrade methylene blue when persulfate ions are present. Persulfate concentration ranged from 1, 2, 4 to 8 mmol/dm−3 in which the highest activity of 4.4 × 10–2 and 7.35 × 10–2 min−1 was obtained with 4 mmol/dm−3 for TiO2–CuO (1:4) and TiO2–CuO/GO (1:1), respectively. The presence of EDTA and isopropyl alcohol reduced the photodegradation. TiO2–CuO coupled with rGO coagulates methylene blue in the presence of persulfate ions and such coagulation is independent of light. The catalyst dosage and the concentration of the dye were varied for the best-performing samples. The antibacterial activity of the synthesized samples was evaluated against the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia. Ti:Cu (1:2)-GO and Ti:Cu (1:4)-GO had the highest antibacterial activity against K. pneumoniae (16.08 ± 0.14 mm), P. aeruginosa (22.33 ± 0.58 mm), E. coli (16.17 ± 0.29 mm) and S. aureus (16.08 ± 0.88).

The development and application of Cu@TiO2@SAPO-34 as better photocatalyst towards degradation of various pollutants

The study developed a novel Cu@TiO2@SAPO-34 nanocomposite for photocatalytic mortification of organic pollutants using modified hydrothermal synthesis. The material was characterized using XRD, BET, XPS, SEM, TEM, UV–vis, and Photoluminescence spectroscopy, confirming high pollutant absorption and photocatalytic capability. The structural analysis identified the emergence of monoclinic CuO and pure anatase phase TiO2, with ligands matching the formation of SAPO-34 at various planes of 2theta degrees. Also, species of Cu-SAPO-34 (35.43 and 65.88°) and TiO2-SAPO-34 (25.56°) were identified. The BET analysis indicated a narrow pore size distribution of 5.59 nm for Cu@TiO2@SAPO-34, with a high surface area to volume ratio of 145.7868 m2. g−1. The optical property analysis revealed that TiO2 exhibited light absorption mainly in the visible region, while Cu@TiO2@SAPO-34 exhibited early adsorption in the ultraviolet region and extended to the visible regions. This was accompanied by a concomitant decrease in band gap energy from 3.09 eV for TiO2 to 2.61 eV for Cu@TiO2@SAPO-34. The Photodegradation experiment demonstrated that TiO2 nanoparticles achieved 83 % degradation of methylene blue (MB) dye solution after 120 minutes under ultraviolet irradiation, while the Cu@TiO2@SAPO-34 composite achieved 98 % within 30 minutes. The novel nanocomposite material was further tested for real wastewater treatment, self-cleaning of the coated film, and nature of wettability, which all confirmed that the novel Cu@TiO2@SAPO-34 composite is superhydrophilic and a better photocatalyst for degrading organic contaminants. The study details the Photodegradation reaction mechanism for the Cu@TiO2@SAPO-34 nanocomposite, comparing it to TiO2 under UV–vis irradiation, and proposes a chabazite-related structure using Biovia Materials Studio 2020.

Mycofabrication of bimetal oxide nanoparticles (CuO/TiO2) using the endophytic fungus Trichoderma virens: Material properties and microbiocidal effects against bacterial pathogens

Bimetallic oxide nanoparticles (NPs) have gained the interest of researchers owing to the synergistic mechanism of action by the elements present. Mycosynthesis of nanostructures is a promising, facile, and an environmentally friendly approach. In the present study, CuO/TiO2 NPs were produced using the cell-free filtrate of the endophytic fungus Trichoderma virens. The reaction of the fungal filtrate with the two metal salts, CuSO4.5H2O and TiO2, resulted in the mycosynthesis of the CuO/TiO2 NPs. The prepared bimetal oxide NPs were characterized using XRD, FTIR spectroscopy, EDX, DLS, zeta potential analysis, XPS, Raman scattering, FESEM, and HRTEM. The mycosynthesized CuO/TiO2 NPs exhibited diffraction peaks characteristic of the monoclinic CuO and tetragonal rutile TiO2 crystal planes. Homogeneity and stability were observed as a result of the biological moieties present in the fungal filtrate, which capped the CuO/TiO2 NPs. The prepared CuO/TiO2 NPs were distributed as flake/plate-like and quasi-spherical/nanorod CuO and TiO2 NPs, respectively. A broad-spectrum antibacterial effect was recorded, with zones of inhibition as follows: foodborne pathogens Escherichia coli (14.34 mm), Salmonella enterica serovar Typhimurium (11.32 mm), and Staphylococcus aureus (9.63 mm); and phytopathogenic bacteria involving Clavibacter michiganensis subsp. michiganensis (Cmm, 12.16 mm), C. michiganensis subsp. capsici (Cmc, 11.26 mm), wild type and streptomycin-resistant Pectobacterium carotovorum subsp. carotovorum (Pcc, 11.06 and 12.37 mm, respectively), and wild type and streptomycin-resistant Xanthomonas citri pv citri (Xcc, 12.48 and 12.69 mm, respectively). The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the CuO/TiO2 NPs were determined using the broth microdilution assay. NP-treated bacterial cells at sub-MICs had rough surfaces with membrane defects and exhibited shrinkage, reduction of cell edges, cracks, and fractures on their surfaces. This study provides insights into the potential of the mycosynthesized CuO/TiO2 NPs as alternative nano-antimicrobial agents, which could be employed for future biomedical, agricultural, and pharmaceutical applications.

Activity, stability, and kinetic study of CuO/TiO2 Janus photocatalyst for rhodamine B degradation

ABSTRACT The CuO/TiO2 photocatalyst was synthesized using hydrothermal and sonochemical methods and subsequently applied to degrade rhodamine B in wastewater. The best synthesis conditions were established, determining Cu(NO3)2 solution concentration of 2.5 wt.% and calcination temperature of 500 °C. The CuO/TiO2 photocatalyst underwent characterization through various techniques, including inductively coupled plasma spectroscopy (ICP), photoluminescence, X-ray diffraction, ASAP, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy. TEM and SEM analyses revealed the presence of TiO2 nanowires and CuO nanoparticles. The Box–Behnken design, encompassing 27 experimental runs, assessed the impact of process variables such as initial dye concentration, pH, UV lamp power, and catalyst dose on the degradation process. The model's R2 value of 0.9893 indicated a high precision in fitting the predicted data to their actual values. Analysis of variance results highlighted UV irradiation power as the most significant variable within the design space. In addition, the CuO/TiO2 photocatalyst demonstrated efficacy under visible light irradiation. Light-expanded clay aggregate beads were chosen as the substrate for photocatalyst immobilization, which enhanced the reaction rate. The stability of CuO/TiO2 was evidenced by about 2% reduction in efficiency after four degradation cycles.

Ag‐Decorated Chrysanthemum‐Like CuO–TiO2 Thin Film: Enhanced Photocatalytic Degradation of Rhodamine B

Photocatalysis has attracted attention as a method for purifying pollutants, but how to simply and efficiently prepare catalyst films with high surface areas is still a challenge. Herein, a chrysanthemum‐like CuO–TiO2–Ag photocatalyst is prepared by anodic oxidation and magnetron sputtering. Scanning electron microscopy and energy dispersive spectrometry analyses show that Ag nanoparticles are uniformly modified on the surface of chrysanthemum‐like CuO–TiO2. Moreover, the influences of the thickness of the TiO2 film and the content of Ag nanoparticles on the degradation of rhodamine B (RhB) are studied by controlling the sputtering time. Among the prepared nanocomposites, the chrysanthemum‐like CuO–TiO2‐2.5‐Ag‐2 proves to have the maximal degradation level with regard to RhB by removing 91.16% RhB after 120 min under UV light. This is because the large surface area offers more active sites. In addition, the trapping experiments show that when CuO–TiO2 is decorated by Ag nanoparticles, this contributes to the movement of a number of photogenerated electrons from the conduction band of TiO2 to Ag, thereby improving the efficiency of charge transfer. The findings reveal that the photodegradation efficiency of the prepared nanocomposites in this study is greatly related to the thickness of the TiO2 film and the content of Ag nanoparticles.

Emerald eco-synthesis: harnessing oleander for green silver nanoparticle production and advancing photocatalytic MB degradation with TiO2&CuO nanocomposite

The tertiary composite of TiO2/CuO @ Ag (TCA) were synthesized by the solid state method using different ratios of TiO2/CuO NCs and Ag NPs. The structural, morphological, and optical properties of nanocomposites were analyzed by scanning electron microscope, Transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra, UV–Vis diffuse reflectance spectra (UV–Vis/DRS) and photoluminescence spectrophotometry. The results showed enhanced activity of TCA hybrid nano crystals in oxidizing MB in water under visible light irradiation compared to pure TiO2. The photocatalytic performance TCA samples increased with suitable Ag content. The results show that the photo degradation efficiency of the TiO2 compound improved from 13 to 85% in the presence of TiO2–CuO and to 98.87% in the presence of Ag containing TiO2–CuO, which is 7.6 times higher than that of TiO2. Optical characterization results show enhanced nanocomposite absorption in the visible region with long lifetimes between e/h+ at optimal TiO2–CuO/Ag (TCA2) ratio. Reusable experiments indicated that the prepared TCA NC photo catalysts were stable during MB photo degradation and had practical applications for environmental remediation.

A novel Magnéli-phase Ti9O17-containing anode by controlled reductive decomposition of calcium copper titanate perovskite under hydrogen atmosphere for paracetamol degradation

CaCu3Ti4O12 (CCTO) materials show high efficacy in water treatment due to their perovskite structure and exceptional chemical stability. Their combination with electro-oxidation and sulfate-based advanced processes represents a promising approach for water treatment applications. CCTO can be modified through various processes to enhance its activity in water treatment. In this study, CCTO was synthesized using ball milling, and the effects of different sintering treatments were evaluated. The treatment with different atmospheres led to CCTO decomposition. Upon sintering under nitrogen, CCTO broke down into the CaTiO3, Cu2O, and rutile TiO2 phases. Conversely, sintering under hydrogen (CCTOH2) led to the reduction of Cu and TiO2 and the creation of Cu and Magnéli phase Ti9O17. CCTOH2 exhibited the highest electrochemical properties due to the presence of Magnéli phases that enhanced electron transfer and conductivity. The decomposition treatment effect on the water treatment performance was evaluated using an electro-oxidation/peroxymonosulfate system. The results showed that when CCTOH2 membranes were used as anodes, paracetamol was completely removed within 10 min. Toxicity was evaluated using Vibrio fischeri. After 1 h, bacterial luminescence inhibition rate dropped to 0 % (from ∼96 % at 2 min), demonstrating paracetamol degradation into non-toxic compounds. Furthermore, CCTOH2 efficacy was tested in the presence of dissolved and colloidal matter from a laboratory-scale secondary effluent. The results demonstrated consistent efficiency in paracetamol degradation in real water and the additional removal of fluorophores. After demonstrating the efficacy of our CCTOH2 membrane, it is now important to test it in large scale experiments.

Synthesis of CuO, ZnO and SnO2 Coupled TiO2 Photocatalyst Particles for Enhanced Photodegradation of Rhodamine B Dye

Environmental pollution is a global problem and dye pollution is one of the major factors. TiO2 shows promising photocatalytic properties that can degrade organic pollutants such as dye under ultraviolet (UV) irradiation. However, TiO2 possesses some disadvantages such as a wide band gap and a high recombination rate of electron-hole pairs. Coupling TiO2 with various metal oxides can enhance photocatalytic properties. In this work, photodepositon (reduction of metal ions on TiO2) followed by the thermal oxidation method were used for the coupling of TiO2 with CuO, ZnO, or SnO2 under various methanol concentrations (25 vol% or 50 vol%) and deposition duration (1 h or 3 h) to observe the effect of these parameters on the photocatalytic degradation activity on Rhodamine B (RhB) dye (up to 90 min). The rate constant of the photodegradation reaction (k) has improved from 0.0141 min−1 (uncoupled TiO2) to 0.0151~0.0368 min−1. Overall, CuO/TiO2 and SnO2/TiO2 samples have shown similar photocatalytic properties (average rate constants of 0.0341 min−1 and 0.0327 min-1, respectively), and both performed better than ZnO/TiO2 in terms of RhB photodegradation (average rate constants of 0.0197 min−1). The difference in photocatalytic performance can be explained by the bandgap of metal oxides and their relative band positions with TiO2. Lastly, CuO/TiO2 (50 vol%, 3 h) and SnO2/TiO2 (50 vol%, 3 h) have shown the best photocatalytic properties respectively due to a longer deposition time and higher concentration methanol, resulting in more deposited materials. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

CuO–TiO2 pilot-plant system performance for solar photocatalytic hydrogen production

The main goal of the present study was to explore photocatalytic performance of the TiO2–CuO mixture, for solar to hydrogen conversion at pilot plant scale under two different irradiation conditions (sunny and partly cloudy), focusing on high-temperature pretreatment of the catalyst mixture to try to improve TiO2 doping with copper. P25–TiO2 and commercial CuO were used with different amounts of Cu (2 wt% or 7 wt% Cu) calcined at 200–400 °C during several hours. Catalysts were tested at pilot plant scale using solar compound parabolic collectors, with glycerol as the sacrificial agent. The photocatalyst prepared after heating at 200 °C for 3 h and with 7 wt% Cu, resulted in higher hydrogen production than under the other heating conditions, and results were slightly better (5–10%) than the reference values with the untreated catalysts. Photocatalytic efficiency was slightly lower at the higher calcination temperature (400 °C). CO2 production and formation of formate and glycolate clearly demonstrated glycerol photoreforming. The Cu from the calcined catalyst remaining on the solid was significantly less (2.5%) than on the non-calcined catalyst (4.2%), with an important fraction of lixiviated copper and copper deposition on the reactor walls. This is a critical drawback that must be considered for large-scale applications.

Experimental investigation on nano refrigeration using TiO2 CuO and Al2O3 as refrigerants

Volatility of heat flow is vital in the refrigeration and cooling frameworks. However, working fluid was utilized in cooling cycle and they were devouring an Earth-wide temperature boost coefficient at undeniable level, However the an Earth- wide temperature boost up capability of HFC134a is marginally high, it should attested that it is a drawn out elective refrigerants which affect the atmosphere of nation.. By expansion of Nano powders to the outcomes of refrigeration cycle which upgrades in the properties of thermos physical and intensity to improve qualities of the working fluid, accordingly working on the execution of the refrigeration framework. In this work, looking at the impact of utilizing, TiO2,Cuo,Al2O3 - R134a and inorganic oil in the fume pressure framework on the dissipating heat transmission coefficient. Polyester Oil was tried alongside reasonableness what's more, natural accommodating refrigerant R-134a. Results show that TiO2,Cuo,Al2O3 nanoparticles concentralization of 0.8 wt% is ideal and gives most noteworthy intensity move improvement and work on the coefficient of Performance(COP). A test rig of mechanical assembly was fabricate as indicated by the public guidelines of India. Nano TiO2 fixations went from 0.05 to 0.8% volume extent and molecule size from 10 to 70 nm. That's what the outcomes show that evaporator warmth move coefficient increments with the utilization of Nano TiO2,Cuo,Al2O3.Finally it is observed that after mixing the Tio2,Cuo, Al2O3 in HFC134A, there was a drastic decrease in evaporator temperatures at faster rate.

Growth and characterization of screen printed TiO2–CuO thick films for optoelectronic applications

We herein report, the deposition of pure and CuO doped TiO2 thick films on glass slides by a cost effective screen printing process, which were then sintered to obtain desired stochiometric composition. Different analytical approaches were used to reveal the precise structural, morphological, optical and electrical characteristics information of pure TiO2 and TiO2–CuO thick films. X-ray diffraction (XRD) patterns exhibit the formation anatase phase of TiO2 and monoclinic phase of CuO. Raman spectra show four TiO2 anatase phase modes only in 100–800 cm−1 region. Infrared (IR) transmittance spectra of these samples recorded in 4000–400 cm−1 region also showed weak, very weak and medium intensity stretching and bending modes of O–Ti–O and Ti–O–Ti bond groups of TiO2 only in 700–400 cm−1 region which further supported the formation of TiO2 anatase phase only. Scanning electron microscopy (SEM) images indicate porous surfaces morphology, irregular shaped as well as size polygonal and spherical shaped particles with tendency to form aggregates along with the EDS analysis that confirms proper composition of the films. The optical band gap energies were derived from diffused reflectance spectroscopy and photoluminescence (PL) spectra. They showed a red shift in peak positions which caused reduction in band gap energy. The CIE diagram clearly depicted blue-green and white emissions. I–V characteristics has been used for calculation of the diode parameters such as ideality factor (n) and barrier height (Φb). The extracted results such as band gap, particle size and electrical parameters suggest that the TiO2–CuO thick films can be used in photovoltaic applications.

Performance evaluation of PdO/ CuO TiO2 photocatalytic membrane on ceramic support for removing pharmaceutical compounds from water.

This study investigated photocatalytic degradation of pharmaceutical compound using CuO or PdO-TiO2 membrane. The synthesized membranes were characterized by some techniques including X-ray powder diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR). The structural properties confirmed that the photocatalytic membranes were successfully prepared on ceramic supports. The PdO-TiO2 and CuO-TiO2 membranes were employed as photocatalytic membranes to degrade metronidazole (MNZ) and diphenhydramine (DPH) in aqueous solutions, respectively. Some parameters affecting the photocatalytic reaction such as pH, initial concentration, and light source were also investigated. The maximum degradation for both pharmaceutical compounds was obtained at basic pH (pH = 10), low initial concentration (C0 = 10ppm) under UV irradiation. At high transmembrane pressure (ΔP = 3bar), the flow rate across the membrane increased up 0.0078 and 0.0082cc/s.cm2 for CuO-TiO2 and PdO-TiO2 photocatalytic membrane respectively while not affected on degradation efficiency (DE). At the same condition operation (C0 = 10ppm, pH = 10, ΔP = 2bar under UV irradiation), the MNZ and DPH degradation of the PdO-TiO2 membrane was 94 and 95% respectively that relatively higher than the CuO-TiO2 membrane. It is probably due to the lower energy band gap of PdO-TiO2 (2.5eV) than CuO-TiO2 (2.7eV). The membrane stability tests confirmed the high performance of the prepared membranes.

Photocatalytic degradation of four emerging antibiotic contaminants and toxicity assessment in wastewater: A comprehensive study

Excessive usage and unrestricted discharge of antibiotics in the environment lead to their accumulation in the ecosystem due to their highly stable and non-biodegradation nature. Photodegradation of four most consumed antibiotics such as amoxicillin, azithromycin, cefixime, and ciprofloxacin were studied using Cu2O–TiO2 nanotubes. Cytotoxicity evaluation of the native and transformed products was conducted on the RAW 264.7 cell lines. Photocatalyst loading (0.1–2.0 g/L), pH (5, 7 and 9), initial antibiotic load (50–1000 μg/mL) and cuprous oxide percentage (5, 10 and 20) were optimized for efficient photodegradation of antibiotics. Quenching experiments to evaluate the mechanism of photodegradation with hydroxyl and superoxide radicals were found the most reactive species of the selected antibiotics. Complete degradation of selected antibiotics was achieved in 90 min with 1.5 g/L of 10% Cu2O–TiO2 nanotubes with initial antibiotic concentration (100 μg/mL) at neutral pH of water matrix. The photocatalyst showed high chemical stability and reusability up to five consecutive cycles. Zeta potential studies confirms the high stability and activity of 10% C-TAC (Cuprous oxide doped Titanium dioxide nanotubes for Applied Catalysis) in the tested pH conditions. Photoluminescence and Electrochemical Impedance Spectroscopy data speculates that 10% C-TAC photocatalyst have efficient photoexcitation in the visible light for photodegradation of antibiotics samples. Inhibitory concentration (IC50) interpretation from the toxicity analysis of native antibiotics concluded that ciprofloxacin was the most toxic antibiotic among the selected antibiotics. Cytotoxicity percentage of transformed products showed r: −0.985, p: 0.01 (negative correlation) with the degradation percentage revealing the efficient degradation of selected antibiotics with no toxic by-products.

Solar Energy Storage Using a Cu2 O-TiO2 Photocathode in a Lithium Battery.

A Cu2 O-TiO2 photoelectrode is pr+oposed for simultaneous solar light energy harvesting and storing of electrochemical energy in an adapted lithium coin cell. The p-type Cu2 O semiconductor layer is the light harvester component of the photoelectrode and the TiO2 film performs as the capacitive layer. The rationale of the energy scheme shows that the photocharges generated in the Cu2 O semiconductor induce lithiation/delithiation processes in the TiO2 film as a function of the applied bias voltage and light power. A photorechargeable lithium button cell drilled on one side recharges with visible white light in ≈9h in open circuit. It provides an energy density of ≈150mAhg-1 at 0.1C discharge current in dark, and the overall efficiency is 0.29%. This work draws a new approach for the photoelectrode role to advance in monolithic rechargeable batteries.

Irreversibility analysis with hybrid cross nanofluid of stagnation point and radiative flow ([formula omitted]) based on engine oil past a stretchable sheet

The present study addressed the physical significance of the entropy generation for the mixed convection time-dependent flow of cross-hybrid nanoliquid due to the stretched surface at a stagnation point. The Plot for heat transport is discoursed by applying the role of thermal radiation under convective conditions. For hybrid nanofluid, engine oil is used as a base liquid with copper (II) oxide CuO and titanium dioxide TiO2 nanoparticles. The existing model is framed in the highly partial differential equation system. The governing equations have been transformed into a set of ODS's using a similar scaling operation. Following this, the resulting ODEs are solved numerically through the BVP4c. The primary goal of this research is to analyze the results of varying the stretching ratio parameter (λ), Weissenberg parameter (We), thermal radiation (Rd), and Biot number (Bi) for both pure TiO2 and CuO + TiO2/ EO hybrid nanofluid, on the velocity, temperature, drag force, heat transfer as well as entropy generation, and Bejan number was studied. A drop in velocity is observed with increasing values of the We and upsurge in velocity for rising value of unsteady parameter (A), while increasing values of both of these parameters are associated with rising temperatures. Copper and titanium oxide nanoparticles are used to increase Engine oil (EO) thermal enactment, making it a more useful base fluid. Further, some significant industrial and engineering applications are related to the present problem discourse.

Sintering Characteristics and Microwave Dielectric Properties of BaTi4O9 Ceramics with CuO–TiO2 Addition

Sintering characteristics, phase evolutions, microstructures, and microwave dielectric properties have been investigated for BaTi4O9 ceramics prepared by traditional low temperature sintering using CuO–TiO2 (CT) additions as aids. The sintering temperature of BaTi4O9 ceramics was found to evidently reduce from 1350 °C to about 1100 °C with a very small amount of 0.5 wt% CT addition. When the CT addition increased to beyond 0.5 wt%, however, it was not expected to further lower the sintering temperature. Meantime, the secondary phases of Ba4Ti13O30, BaTiO3, and TiO2 were observed in these BaTi4O9-based ceramics when the CT content was beyond 2 wt%. With the introduction of the CT addition, the permittivity (ε) had little enhancement, and the temperature coefficient of the resonant frequency (τf) was improved to near zero. The BaTi4O9 ceramics with 0.5 wt% CT additions, sintered at 1100 °C, exhibited excellent microwave dielectric properties, such as ε = 36.9, Q × f = 23100 GHz, and τf = 2.5 ppm/°C. In addition, the densification mechanism and variations of the microwave dielectric properties have also been discussed with the crystal phase and microstructure’s evolution.

Boosting solar-driven N2 to NH3 conversion using defect-engineered TiO2/CuO heterojunction photocatalyst

Ammonia (NH3) is one of the important energy sources for sustainable chemical products and carbon-free energy carriers. Artificial N2 photofixation is one of the promising approaches for the clean production of NH3 using photocatalysts in N2-dissolved water as a hydrogen source. We prepared defect-engineered TiO2/CuO heterojunction photocatalysts by the simple evaporation-induced self-assembly (EISA) method followed by post-thermal annealing under inert gas flow. The formation of a type-Ⅱ using TiO2 and CuO facilitated light absorption in near IR to UV light and the separation of photoexcited electron-hole pairs. In addition, the further post-thermal annealing under N2 gas flow resulted not only in an increase in crystallinity for the photoactive Anatase TiO2 and Tenorite CuO in the bulk but also in the in-situ formation of Ti3+ defect sites on the TiO2 surface. The increased crystallinity enhanced the photoexcited charge transport, while the defect sites improved N2 adsorption and activation, promoting the photocatalytic conversion of N2 to NH3. The defect-engineered TiO2/CuO photocatalysts exhibited a high NH3 production rate (1.575 μ mol g−1h−1) under visible light irradiation (λ≥ 420 nm) without any sacrificial agent, this value is 9.4 times and 2.5 times higher than those obtained with pristine TiO2 and TiO2/CuO photocatalysts, respectively. This work clearly demonstrates the synergistic effect of heterojunction and defect-engineering and provides insights into how each strategy can affect solar-driven NH3 production.

Metastability and Photoelectrochemical Properties of Cu2SnO3 and Cu2–xLixTiO3: Two Cu(I)-Based Oxides with Delafossite Structures

Metastable, p-type Cu(I)-based semiconductors were synthesized using cation-exchange reactions between delafossite-type layered precursors and CuCl flux, yielding Cu2SnO3 (I) and Cu2–xLixTiO3 (II, xmin ∼ 0.4). These represent the first reported crystalline semiconductors found in the Cu–Sn–O or Cu–Ti–O chemical systems (and not currently predicted within any materials databases), with their kinetic stabilization requiring a relatively low reaction temperature of ∼475 °C. Both phases crystallize in the monoclinic crystal system in the space group C2/c, exhibiting edge-shared hexagonal “MO3” (M = Sn or Ti) layers that also contain octahedrally coordinated Li(I)/Cu(I) cations. These layers are bridged by linearly coordinated Cu(I) cations. Magnetic susceptibility measurements confirm the +1 oxidation state of the copper cations. The optical band gaps were found to be indirect and to significantly red shift with the Cu(I) content, down to ∼2.31 eV for I and ∼1.46 eV for II. Electronic structure calculations show that the decreased band gaps can be attributed to a higher energy valence band derived from the filled 3d10 orbitals of the Cu(I) cations, which most notably arise from the octahedrally coordinated Cu(I) cations within the layers. Total energy calculations reveal an increasing metastability with respect to decomposition to Cu2O and SnO2 or TiO2 as a result of occupation of the intralayer sites by Cu(I) cations. In both phases, their edge-shared hexagonal layers lead to highly dispersive conduction bands and small electron effective masses of ∼0.51 me for I and ∼0.41 me for II. Polycrystalline films of both were deposited onto fluorine-doped tin oxide slides and exhibited p-type photocurrents under 100 mW cm–2 irradiation in the range of ∼50 to 250 μA cm–2. This study thus reveals new fundamental relationships between the origin of metastability in Cu(I)-oxide semiconductors, i.e., octahedral coordination, and enhanced optical and photoelectrochemical properties.