Cuprous Oxide Research Articles

Additive-free electroless deposition on graphene/copper foil: Photo-induced and defect-assisted approach for environmentally friendly plating

The environmental toxicity of chemicals used in electroless plating process is often overlooked. In fact, the wastewater from the electroless plating process contains metal complexes, reducing agents and stabilizers that can create hazard to our environment. To address this concern, an additive-free electroless deposition process on graphene/Cu foil is proposed. The defect structure of graphene plays a pivotal role by acting as a reservoir for concentrating photoelectrons generated from ultra-thin cuprous oxide (Cu2O) located at the interface of graphene and Cu foil upon exposure to light irradiation. In the Cu ion solution, Cu ions were anchored on the defect sites and formed a Cu-C4 structure with graphene. The Cu-C4 sites accumulate abundant photoelectrons and trigger the reduction of Cu ions to form island-like growth of Cu, which immediately was oxidized to Cu2O, leaving only a small portion of metallic Cu. Concurrently, the presence of Cu ions induces the generation of additional defect sites on graphene, providing further growth sites for Cu deposition. This process continues until the entire graphene surface is covered by the deposited Cu2O. Ultimately, the deposition of metallic oxides with lower redox potential can be achieved. The proposed deposition mechanism assisted by irradiation of photocatalyst and defect structure of graphene material provides a truly environmentally friendly electroless plating process. By eliminating the need for additives and significantly reducing the environmental hazards associated with electroless plating, this method holds great promise for sustainable materials manufacturing.

Key Strategies on Cu2O Photocathodes toward Practical Photoelectrochemical Water Splitting.

Cuprous oxide (Cu2O) has been intensively in the limelight as a promising photocathode material for photoelectrochemical (PEC) water splitting. The state-of-the-art Cu2O photocathode consists of a back contact layer for transporting the holes, an overlayer for accelerating charge separation, a protection layer for prohibiting the photocorrosion, and a hydrogen evolution reaction (HER) catalyst for reducing the overpotential of HER, as well as a Cu2O layer for absorbing sunlight. In this review, the fundamentals and recent research progress on these components of efficient and durable Cu2O photocathodes are analyzed in detail. Furthermore, key strategies on the development of Cu2O photocathodes for the practical PEC water-splitting system are suggested. It provides the specific guidelines on the future research direction for the practical application of a PEC water-splitting system based on Cu2O photocathodes.

Tunable optical properties of ATO-CuO hybrid nanofluids and the application as spectral beam splitters

Nanofluids containing metal nanoparticles have promising application prospects in the spectral beam splitters (SBSs) of photovoltaic/thermal (PV/T) setups on the merits of the tunable spectral absorption characteristic and relatively low price. While the existing nanofluid-based SBSs show some difficulties in large-scale industrial applications, such as their poor stability, sophisticated manufacturing process, etc. In this paper, a cheap and stable hybrid nanofluid containing antimony tin oxide (ATO) and cupric oxide (CuO) nanoparticles has proven to be a good candidate for SBSs. ATO has high absorption in the infrared region while CuO shows strong absorption for ultraviolet and visible light, so ATO and CuO nanoparticles have complementary optical properties and the spectral absorption of ATO-CuO hybrid nanofluids is expected to be effectively regulated by adjusting nanoparticles’ composition. Meanwhile, the increase in nanoparticle concentration can enhance the light absorption ability of hybrid nanofluids in the full spectrum. The hybrid nanofluid SBS with a 5:5 ATO:CuO mass ratio and 200 ppm concentration proves to perform best and the merit function is as high as 1.679 (worth factor is 3), which is highly competitive among the metal-based nanofluid SBSs from literature.

Investigation of Mineral Oil and CuO Mixed Synthetic Oil in Compression Ignition Engines: A Comparison of Physicochemical Attributes

Mineral oil resources are depleting rapidly, and the slower conventional oil biodegradation process results in environmental pollution. To resolve this issue, cupric oxide (CuO) nanoparticles (1% wt) were introduced into a base oil to improve the lubricating capability of castor oil. In addition, 1% wt. sodium dodecyl sulfate was also blended with the base oil in order to attain the maximum dispersion stability of CuO nanoparticles in the castor oil. Afterward, thermophysical property, atomic absorption spectroscopy, and Fourier transform infrared radiation (FTIR) testing of the lubricant oil sample were performed before and after 100 h of engine operations at 75% throttle and 2200 rpm for each lubricant sample in order to check the capability of the novel oil with mineral oil. Compared with the natural mineral oil, the behavior of the CuO-based lubricant has essentially the same physical features, as measured according to ASTM standard methods. The physicochemical properties like (KV)40 °C, (KV)100 °C, FP, ash, and TBN decrease more in the case of the synthetic oil by 1.15, 1.11, 0.46, 1.1, and 1.2% than in the conventional oil, respectively. FTIR testing shows that the maximum peaks lie in the region of 500 to 1750 cm−1, which shows the presence of C=O, C-N, and C-Br to a maximum extent in the lubricant oil sample. AAS testing shows that the synthetic oil has 21.64, 3.23, 21.44, and 1.23% higher chromium, iron, aluminum, and zinc content. However, the copper and calcium content in the synthetic oil is 14.72 and 17.68%, respectively. It can be concluded that novel bio-lubricants can be utilized as an alternative to those applications that are powered by naturally produced mineral oil after adding suitable additives that further enhance their performance.

Nanostrategy of Targeting at Embryonic Trophoblast Cells Using CuO Nanoparticles for Female Contraception.

Effective contraceptives have been comprehensively adopted by women to prevent the negative consequences of unintended pregnancy for women, families, and societies. With great contributions of traditional hormonal drugs and intrauterine devices (IUDs) to effective female contraception by inhibiting ovulation and deactivating sperm, their long-standing side effects on hormonal homeostasis and reproductive organs for females remain concerns. Herein, we proposed a nanostrategy for female contraceptives, inducing embryonic trophoblast cell death using nanoparticles to prevent embryo implantation. Cupric oxide nanoparticles (CuO NPs) were adopted in this work to verify the feasibility of the nanostrategy and its contraceptive efficacy. We carried out the in vitro assessment on the interaction of CuO NPs with trophoblast cells using the HTR8/SVneo cell line. The results showed that the CuO NPs were able to be preferably uptaken into cells and induced cell damage via a variety of pathways including oxidative stress, mitochondrial damage, DNA damage, and cell cycle arrest to induce cell death of apoptosis, ferroptosis, and cuproptosis. Moreover, the key regulatory processes and the key genes for cell damage and cell death caused by CuO NPs were revealed by RNA-Seq. We also conducted in vivo experiments using a rat model to examine the contraceptive efficacy of both the bare CuO NPs and the CuO/thermosensitive hydrogel nanocomposite. The results demonstrated that the CuO NPs were highly effective for contraception. There was no sign of disrupting the homeostasis of copper and hormone, or causing inflammation and organ damage in vivo. In all, this nanostrategy exhibited huge potential for contraceptive development with high biosafety, efficacy, clinical translation, nonhormonal style, and on-demand for women.

Large scale purification in semiconductors using Rydberg excitons

Improving the quantum coherence of solid-state systems is a decisive factor in realizing solid-state quantum technologies. The key to optimize quantum coherence lies in reducing the detrimental influence of noise sources such as spin noise and charge noise. Here we demonstrate that we can utilize highly-excited Rydberg excitons to neutralize charged impurities in the semiconductor Cuprous Oxide - an effect we call purification. Purification reduces detrimental electrical stray fields drastically. We observe that the absorption of the purified crystal increases by up to 25% and that the purification effect is long-lived and may persist for hundreds of microseconds or even longer. We investigate the interaction between Rydberg excitons and impurities and find that it is long-ranged and based on charge-induced dipole interactions. Using a time-resolved pump-probe technique, we can discriminate purification from Rydberg blockade, which has been a long-standing goal in excitonic Rydberg systems.

Tuning of Surface Wettability and Interfacial Electron Transfer in Cupric Oxide Nanosheets for Highly Efficient Hydrogen Peroxide Production and Electro-Fenton Catalysis

Tuning of Surface Wettability and Interfacial Electron Transfer in Cupric Oxide Nanosheets for Highly Efficient Hydrogen Peroxide Production and Electro-Fenton Catalysis

E-beam irradiation-induced synthesis of hydroxyethyl cellulose/(Cu2O-rGO)/BiVO4-based nanocomposite for photocatalytic remediation of wastewater under visible light

Using E-beam irradiation as an eco-friendly technique for initiation and crosslinking, a series of Hydroxyethyl Cellulose-poly vinyl alcohol copolymer hydrogels were synthesized as templates for cuprous oxide (Cu2O), reduced graphene oxide (rGO) and bismuth vanadate (BiVO4) nanoparticles to be used as nanocomposites photocatalysts for methylene blue (MB) dye decolorization using visible light. Preparation conditions were optimized to ensure the construction of a good network architecture and therefore the highest gelation degree. For the preparation of (Cu2O@rGO)/BiVO4 nanocomposites, a series of rGO was decorated by Cu2O using the precipitation method, followed by mixing with BiVO4 which was synthesized hydrothermally. (EDX), (XRD), (TEM), and (SEM) were used for nanoparticle characterization. The thermal characteristics of the fabricated nanocomposites were evaluated using thermal gravimetric analysis. The presence of rGO enhanced the decolorization efficiency of MB about 20 % higher than that of (HEC-PVA)/Cu2O which achieves only (59 %) decolorization efficiency. After the addition of BiVO4 NPs, the decolorization efficiency increased to reach 90 % after 150 min at pH 11 using a 10 ppm MB solution. The developed (HEC-PVA)/(Cu2O@rGO)/BiVO4 photocatalyst exhibits efficient reusability for 5 cycles. Treated dyed water shows a germination index (GI) of 82 % suggesting its suitability for irrigation of playgrounds and gardens.

Grain boundary passivation in cuprous oxide thin films via nitrogen annealing

In this work, polycrystalline cuprous oxide (Cu2O) films deposited by magnetron sputtering were annealed in situ in N2 atmospheres. Room-temperature and temperature-dependent Hall-effect measurements were performed on as-deposited and N2-annealed Cu2O films to probe the electrical transport mechanisms. The results show that the hole mobility of 0.8 Pa N2-annealed Cu2O film is enhanced compared with its as-deposited counterpart. It is shown that at low temperatures, the hole mobilities of Cu2O films appear to be limited by grain boundary scattering, while acoustic-phonon scattering comes into play at elevated temperatures. Moreover, the grain boundary potential barrier height which inhibits the hole transport is found to be reduced by N2-annealing at 0.8 Pa, thereby leading to the observed improvement in the hole mobility. It is thought that N2 is mainly concentrated at the grain boundaries in polycrystalline Cu2O films, thus passivating the grain boundary defect trap states. The results reported in this work suggest that N2-annealing induced grain boundary passivation could be an effective method to improve the photoelectric properties of polycrystalline Cu2O films.

Sustainable, efficient, and synergistic photocatalytic degradation toward organic dyes and formaldehyde gas via Cu2O NPs@wood

Cuprous oxide (Cu2O) nanoparticles (NPs) was anchored on wood by simple spraying method, then both soft and hard wood has been endowed efficient function photocatalytic degradation toward organic dyes and formaldehyde gas synergistically. The best recycle ability of wood based photocatalyst toward organic pollutants was achieved, which was characterized by photocatalytic degradation efficiency of methylene blue (MB) more than 95% after 100 cycles, and formaldehyde gas over 85% after 60 cycles. Cu2O NPs@wood performed much lower forbidden bandwidth (Eg), which accelerated to generate much more radical of e− and finally promoted the capacity of photocatalytic degradation. The proposed Cu2O NPs@wood catalysts has potential to be applied both in the field of wastewater and air pollution remediation.

Photocatalysis of silicon nanowires decorated with metallic nanoparticles and graphene oxide under different light intensities

This work shows silicon nanowires (SiNWs), decorated with different nanoparticles, as a photocatalytic material under different lighting conditions. In this system, the comparison between different materials and the influence of light intensity on their performances are studied. On the other hand, the synthesis of SiNWs was done by a metal-assisted chemical etching. The decoration with nanoparticles of copper CuNPs and cuprous oxide CuO2NPs was conducted with the electroless technique. Graphene oxide (GO) lamellar particles passing through an atmospheric pressure plasma (APPJ) were instantaneously ionized losing OH radicals and connecting them into a continuous coating around the SiNWs nanostructures. Such a layer with a large contact area among SiNWs/GO/Cu/CuO2 was obtained with a small thickness of about 10–20 nm. This is proposed to allow and increase charge carrier transference to the aqueous solution for redox reactions to degrade the dye molecules. Through statistical analysis, we compared the percentages of the decrease in methyl orange concentration used to measure the photocatalytic performance. SiNWs – CuNPs surfaces, in combination with high-intensity light, exhibit higher degradation percentages and rate constants. The graphene oxide coatings were deposited on monocrystalline silicon wafers and silicon nanowires, constituting a semiconductor-semiconductor heterojunction. This is an innovation proposed in this work that could lead to the fabrication of semiconductor heterojunctions with Z-scheme complementarity.

Efficiency Improvement of Photoelectrochemical Solar Cell Applications by Using Ternary Hybrid MoS2/g-C3N4/Cu2O

In this paper, molybdenum disulfide MoS2 was hybridized with graphene carbon nitrite (g-C3N4) and Cu2O in order to enhance the photoelectrochemical (PEC) activity and increase the light absorption range of Cu2O thin film. The melamine powder was poured in an empty container and then heated in a furnace to attain the powder. The ternary hetero-epitaxial growth was achieved by growing of MoS2/g-C3N4 on the Cu2O hybrid by a partial thermal oxidation process. The characteristics of MoS2/g-C3N4/Cu2O hybrid film were investigated through XRD, FT-IR and photoelectronchemistry-related measurements. The PEC behavior of the ternary hybrid electrode was investigated using current-voltage test under illumination. The efficiency calculated from current-voltage test under illumination shows that the presence of graphene carbon nitrite and molybdenum disulphide within the film networks, despite its low content, could stimulate substantial improvement in maximum photoconversion efficiency from 0.036% to 0.33%. This improvement is attributable to the enhancement of the electron-transferring proficiency upon the insertion of g-C3N4 and, MoS2 as confirmed by X-Ray Diffraction Analysis (XRD). The PEC test results signify that the photoelectrochemical activity of the MoS2/g-C3N4/Cu2O ternary hybrid is much higher than that of subtrate. The mechanisms accountable for the enhanced PEC behavior of the MoS2/g-C3N4/Cu2O ternary hybrid are discussed in detail.Keywords: Cuprous Oxide, J-V Characteristic, Hetero-structure, Photoelectrochemical, Thermal Oxidation.

Understanding atomic interaction between cuprous oxide film and aggressive chloride solution

Considering the structural complexity of actual copper (Cu) passive films consisting of Cu2O, the multiple roles of aggressive chloride anion (Cl–) on Cu2O are revealed through first-principles calculations. Despite different Cl– adsorption susceptibilities of various Cu2O surfaces, similar surface O vacancy formation mechanisms promoted by Cl– adsorption are elucidated, accompanying with further Cu vacancy propagation. Increasing surface Cu vacancy concentration and unchanged Cu vacancy diffusion coefficient induced by Cl– adsorption lead to increasing diffusion flux. These results reveal the atomic interaction between Cu2O film and Cl ion, which is helpful to understand the depassivation mechanism of Cu.

Comparative photocatalytic study of visible light driven BiVO4, Cu2O, and Cu2O/BiVO4 nanocomposite for degradation of antibiotic for wastewater treatment.

Semiconductor-based photocatalysts have become increasingly used in the removal of pollutants from wastewater, especially antibiotics. A series of composite-based cuprous oxide and bismuth vanadate (Cu2O/BiVO4) composite-based photocatalysts were synthesized by using the chemical method. The structure of the Cu2O/BiVO4 composite was verified by using x-ray diffraction, scanning electron microscopy, photoluminescence, Fourier transform infrared spectroscopy, and UV-visible spectra. The degradation of methylene blue (MB) and tetracycline (TC) was investigated to check the photocatalytic activity of the Cu2O/BiVO4 composite series. The quantity of Cu2O was varied from 1% to 7% by weight to prepare the series of Cu2O/BiVO4 composites. The analysis of results verified that 5% Cu2O/BiVO4 exhibits an outstanding photocatalytic activity as compared to 1%, 3%, and 7% Cu2O/BiVO4, pure Cu2O, and pure BiVO4 under visible light irradiation. The optimum value of photocatalytic degradation achieved with 5% Cu2O/BiVO4 was 97% for MB dye and 95% for TC in 120min, which is greater than the photocatalytic degradation of pure BiVO4 (MB 45% and TC 72%), pure Cu2O (MB 57% and TC 80%), 1% Cu2O/BiVO4 (MB 72% and TC 85%), 3% Cu2O/BiVO4 (MB 83% and TC 88%), and 7% Cu2O/BiVO4 (MB 87% and TC 91%). The stability and reusability of Cu2O/BiVO4 were also investigated. To check the major role of trapping in degradation, a trapping experiment was also performed by using three trapping agents: BQ, EDTA, and tBuOH. The results showed that Cu2O/BiVO4 exhibits an improved photocatalytic activity in the degradation of antibiotics in polluted water because the recombination rate of the electron-hole pair decreased and the surface area increased, which increased the active sites for redox reactions. Such a photocatalytic composite with high efficiency has various applications, such as energy production, environmental remediation, and water remediation.

Oxidation dynamics of Cu thin film on Si surface by mass analyzed O+ ion implantation and study their electrical and optical properties

In this article, the ion beam-induced oxidation dynamics of copper (Cu) thin film and transport properties of the ion-modified films, deposited on Si substrate by e-beam evaporation, are investigated. Low energy (10 keV) O+ ion bombardment on Cu films at normal incidence leads to the formation of cuprous oxide (Cu2O) and cupric oxide (CuO) phases at different stages of bombardment. The dynamical change of the cuprous oxide (Cu2O) phase to the mixture of Cu2O and CuO phases with increasing ion fluence is observed via X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray diffraction. Ion implantation leads to a decrease in crystalline size with an increase in ion fluence. The increase of oxygen concentration and the absence of foreign impurities in Cu films at higher ion fluence are also measured by XPS and Energy-Dispersive X-ray spectroscopy. The oxygen concentration reduces from 82 % to 58 % for the cuprous oxide phase, whereas the same increases from 18 % to 42 % for the cupric oxide phase. The optical response due to enhancement of the oxygen atoms in ion-modified Cu thin films investigated using UV–visible spectrophotometer, shows higher absorption in the visible region compared to untreated Cu film. Post-bombardment changes in resistivity of copper oxide films, containing the mixture of two chemical phases, exhibit metallic and semiconducting behavior at temperatures 10–110 K and above 110 K, respectively. Temperature varying (300–350 K) Hall measurements of the oxygen implanted Cu film shows changes in the threshold values of mobility (1.4 to 2.4 cm2/Vs), resistivity (18 × 10−6 -150 × 10−6 Ω-cm) and carrier concentration (2 × 1022 -15 × 1022 cm−3). The potential applications of pure copper oxide films prepared by low-energy ion implantation without thermal treatment are also addressed here.

Reduced graphene oxide-cuprous oxide composites for low concentration ozone detection

In this research, cuprous oxide (pristine Cu2O) and rGO (reduced graphene oxide)-doped Cu2O were prepared using a simple synthetic route and adopted as sensitive materials for ozone detection. The microstructural, morphological and compositional properties of as-prepared samples have been analyzed by several characterization techniques including X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Energy dispersive spectrometer (EDS), UV-Visible spectrophotometer (UV–vis), Multi-functional field emission scanning electron microscope (FESEM), X-ray Photoelectron Spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). Meanwhile, the sensing features of as-prepared samples have been investigated carefully and the as-prepared 0.5 wt% rGO-Cu2O exhibited best ozone sensing properties, such as high stability, sensitivity and selectivity. It can be found that the response value of 0.5 wt% rGO-Cu2O-based sensor towards 20 ppb ozone and 1 ppm ozone were 9.2/1734, respectively, and the corresponding response and recovery times were 11/64 s and 11/411 s, respectively. More importantly, the detection limit of the 0.5 wt% rGO-Cu2O sensor was as low as 0.1 ppb. Furthermore, the possible mechanism for the enhanced sensing performance of the as-prepared rGO-Cu2O has been discussed.

On the dielectric properties and conduction mechanism in cuprous oxide thin films grown on (111)-oriented MgO substrates by means of non-reactive DC magnetron sputtering

On the dielectric properties and conduction mechanism in cuprous oxide thin films grown on (111)-oriented MgO substrates by means of non-reactive DC magnetron sputtering

Synthesis and characterization of CuO/Co0304 and CuO/Fe:O; composites and their potential application in the photocatalytic CO2 reduction process

Cupric oxide is a prominent material used as a photocatalyst due to its narrow bandgap; coupling it with other metal oxide semiconductors improves its efficiency due to the favored charge transference. This work reports the synthesis of the composites CuO/CosO4 and CuO/Fex0s, prepared in a sol-gel and hydrothermal two-step methodology to disperse the cocatalyst particles over CuO. The effect of the cocatalyst's concentration over CuO in its structural, optical, and photocatalytic properties was analyzed. A better distribution of the Fe203 particles over CuO was observed, which resulted in the largest cfficiency in the photocatalytic CO2 reduction to formic acid. Despite this, increasing the cocatalyst concentration reduces the photocatalytic activity due to the surface saturation, probably causing the formation of recombination centers. The presented methodology represents a low-cost way to obtain highly efficient composites in photocatalytic reductive processes.

Tunable room-temperature ferromagnetism in RF magnetron sputtered Al2Cr2Cu2O8 thin film

Metal oxide solid solution thin films containing ternary mixtures of Alumina (Al2O3), Chromia (Cr2O3) and Cupric oxide (CuO) were successfully prepared combinatorially on FTO, quartz glass and Si substrates using radio frequency (RF) magnetron sputtering (vertical geometry; on-axis sputtering) technique with RF powers of 200 W and 100 W. XRD analysis prove the development of tetragonal phase Al2Cr2Cu2O8 in sputtering target. Al2Cr2Cu2O8 film deposited on Si wafer and quartz glass exhibits amorphous nature, whereas, the film deposited on FTO substrates exhibit crystalline structure with tetragonal phase owing to polycrystalline nature of the FTO substrates. Formation of high compositional purity with acceptable stoichiometric ratio of ternary metal oxide mixtures of Al2Cr2Cu2O8 was ascertained from the EDX spectra. The thicknesses of Al2Cr2Cu2O8 thin films are found to be in the ranges from 259 to 314 nm. Optical study showed that the optical energy band gap of Al2Cr2Cu2O8 thin film deposited on quartz substrates increased to 3.84 eV from 3.78 eV with decreasing RF power from 200 W to 100 W. The spin orbital splitting (SOS) between Cr 2p1/2 - Cr 2p3/2 and Cu 2p1/2 - Cu 2p3/2 were measured to be 9.9 eV and 19.3 eV by XPS for 200 W sputtered Al2Cr2Cu2O8 film on quartz substrate, which are the characteristics of Cr3+ and Cu2+ oxidation states, respectively. In addition, XPS analysis also confirms the presence of various oxygen vacancies in Al2Cr2Cu2O8 thin films (as-deposited and 1000 °C annealed films) on quartz substrate with RF power of 200 W, which is the most favorable condition for the presence of room temperature ferromagnetic properties observed in the present study.

Synergistic effect of antiferromagnetic hematite on cuprous oxide nanocomposite: enhanced catalytic activity and reusability for N-arylation of imidazole

Synergistic effect of antiferromagnetic hematite on cuprous oxide nanocomposite: enhanced catalytic activity and reusability for N-arylation of imidazole