CuO Surface Research Articles

Carbonate shell regulates CuO surface reconstruction for enhanced CO2 electroreduction

Carbonate shell regulates CuO surface reconstruction for enhanced CO2 electroreduction

A DFT and Microkinetic Study of Propylene Selective Oxidation on Cu2O(111) Surface with O2: Chlorinum Effect

AbstractSpin‐polarized density functional theory (DFT) +U calculation was performed to study propylene selective oxidation on Cu2O(111) and Cl−Cu2O(111) surfaces. The mechanism included two pathways: the allylic hydrogen stripping (AHS) pathway and the epoxidation pathway, and acrolein, propylene oxide (PO), propanal and acetone can be formed. The calculated results found that the C3H6*+OO*→OOMMP2*→PO* route can be regarded as the preferred formation route of PO on these two surfaces. On clean surface, acrolein can be regarded as the main product, then other products selectivity follows: acetone>PO>propanal. On Cl−Cu2O(111) surface, acrolein was also the main product, and the apparent activation energy of acrolein (1.97 eV) was approximated to the apparent activation energy of PO (2.04 eV), other products selectivity follows: PO>propanal>acetone, which means that the selectivity of PO can be improved by the effect of Cl. Microkinetic simulation confirm that PO selectivity can be elevated qualitatively, and found that OOMMP2*→PO2*+O* is the rate determining step on pure surface and C3H6*+OO*→OOMMP2* is the rate controlling step on the doped−Cl surface. From this work, it can be found the O−O bond in O2 can be activated effectively by the presence of Cl, enhancing the selectivity of PO.

Investigating the effect of Cu underlayer and FTO etching towards photoelectrochemical performance enhancement of Cu2O photoelectrode

Cuprous oxide (Cu2O) exhibits potential as a photoactive material for photoelectrochemical water splitting, owing to its appropriate bandgap, efficient charge carrier separation, and ability to enhance solar-driven hydrogen production. This study investigates the influence of substrate etching, Cu underlayer and Cu2O electrodeposition time, and annealing time on enhancing the photoelectrochemical (PEC) performance. Electrodeposition and thermal oxidation techniques were used to fabricate the Cu2O/Cu/FTOe-A photocathode. It has been observed that FTO etching improves adhesion, light transmission, and efficiency. A Cu underlayer also impacts the PEC performance, wherein an ideal thickness of Cu leads to enhanced PEC performance. This study also focuses on the annealing time that leads to CuO layers and nanowires forming on the Cu2O surface. The structural and chemical changes before and after annealing are confirmed via XRD, XPS, AFM and FESEM analyses. UV–Vis analysis also reveals that the presence of Cu underlayer, FTO etching, and the annealing process affect the electrical properties and light absorption capacities of the Cu2O photoelectrode. Electrochemical impedance analysis (EIS) and Mott-Schottky analysis have provided insights into the enhanced charge transfer properties and band bending in the Cu2O/Cu/FTOe-A, resulting in enhanced PEC performance. Overall, this study provides significant insights into the understanding and enhancement of Cu2O/Cu/FTOe-A photocathodes for potential use in PEC water splitting applications.

Selective methanol production via CO2 reduction on Cu2O revealed by micro-kinetic study combined with constant potential model

High efficiency electrocatalysis of greenhouse gas CO2 to liquid fuel methanol attracts great attentions that allows energy transformation from renewable electric energy to storable chemical energy. Catalytically converting CO2 to methanol using green hydrogen is a promising pathway to achieve carbon neutrality. In this work, the catalytic activity and product selectivity of the electrochemical CO2 reduction reaction on Cu2O were studied using a micro-kinetic model based on Marcus charge transfer theory. The constant potential model under the grand-canonical ensemble enables the accurate description of binding energies and ground-state charge transfer upon surface adsorption as a function of electrode potential. Firstly, the potential-dependent activation energies and rate constants of all possible elementary reactions involved in CO2 reduction are calculated. Then, the surface coverage and its derivative can be obtained in a steady-state approximation. Finally, the total reaction rate and partial reaction rate can be deduced, allowing for direct comparison with catalytic activity (current density) and product selectivity (Faradaic efficiency). It is found that CH3OH is the dominant product on the Cu2O(111) surface, while CO is the main product on the Cu2O(110) surface. Based on the derived total and partial reaction rates under the steady-state approximation, it is demonstrated that Cu2O(111) exhibits the highest electrocatalytic activity and methanol selectivity at U = −0.6 V vs. SHE. This research presents a methodology for predicting apparent electrocatalytic performance from microscopic reaction energy calculations, which can be applied to other important electrocatalytic reaction mechanisms and performance predictions.

Synthesis and Characterization of Polyaniline/CuO Nanocomposites with Various Temperature

Polyaniline (PANI) metal oxide composites are known for their high electrical conductivity, environmental stability, and enhanced mechanical strength, making them valuable in applications such as sensors, batteries, and electromagnetic shielding. This study focuses on synthesizing and characterizing PANI/CuO nanocomposites to examine their structural, morphological, and functional properties at different synthesis temperatures. By integrating the conductive polymer PANI with copper oxide (CuO), a p-type semiconductor with a narrow band gap, the material’s capabilities are significantly enhanced. The oxidative polymerization of aniline, the process by which PANI is formed, requires precise control of oxidizing agents and reaction conditions, as these factors directly affect the polymerization, conductivity, and overall properties of the resulting nanocomposite. The PANI/CuO nanocomposites were synthesized at three different temperatures: 10℃, 25℃, and 50℃, to determine how temperature affects their characteristics. Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) were employed to analyze these nanocomposites. FTIR results revealed shifts in the quinoid and benzenoid rings, indicating hydrogen bonding between the NH group of PANI and the CuO surface, which accelerates charge transfer. The SEM analysis showed that while pure PANI exhibits a uniform globular morphology, the PANI/CuO nanocomposites display a nanorod morphology. These morphological differences impact the surface area and electrical conductivity of the composites, highlighting the significance of temperature in tailoring the material's properties for specific applications.

Non-radical activation of persulfate by CuO catalyst for degradation of antibiotics

Advanced oxidation process (AOP) based on persulfate (PS) activation has attracted numerous attentions for antibiotic elimination due to the high stability and low cost of PS. In this work, a non-radical activation of PS by CuO catalyst was developed to efficiently degradation of antibiotics. Employing moxifloxacin (MOX) as model pollutant, the CuO/PS system showed excellent degradation rate for 100 mg L−1 MOX that is 13.2 and 7.7 times higher for than the single CuO and PS, and meanwhile the performance is also much better than the typical AOP heterogeneous catalyst Fe2O3 in both neutral and acidic solutions. The optimization experiments indicate the optimal PS concentration is 2.5 mM, and the CuO/PS system can work in a wide pH range for different MOX concentrations. Furthermore, the CuO catalyst has high structural stability and catalytic durability, and the CuO/PS system has good practicality that can degrade a variety of antibiotics and be used in different aquatic environments. Based on various characterizations, a non-radical PS activation route on the CuO surface was proposed. Finally, toxicity assessment of the detected intermediates implies that the toxicity and the potential risk to the environment were effectively decreased. This work testifies PS can be efficiently activated by CuO through a non-radical pathway and presents superior performance for antibiotic elimination.

Insights into the Structure and Activity of Bimetallic Au/Cu2O Catalysts during CO2 Electroreduction to C2 products

Despite its promising performance for C2+ product formation in electrochemical reduction of CO2 (CO2RR), Cu-based catalysts exhibit a relatively poor selectivity towards important chemical intermediates such as ethylene and ethanol. Up to 16 different products can typically be formed during CO2RR.1 Cu is the only element that can form C-C bonds at an appreciable rate.2 Therefore, it is critical to better understand the active sites of Cu-based electrocatalysts, as it can lead to better catalyst design with improved selectivity towards desired products. A common approach is to investigate the reactivity of well-defined surface terminations of Cu, which can be achieved by employing shape-controlled (nano)particles.3 Here, we expanded on such studies by evaluating the impact of Au on well-defined Cu2O surfaces for the electrochemical reduction of CO2. This promoter metal was chosen, because it can reduce CO2 to CO, which is widely accepted as the key intermediate for C-C coupling.2,4 In this study, 40 nm Cu2O nanocubes that predominantly expose the (100) facet were synthesized with a ligand-free method. The (100) facet is more active in the production of ethylene at the expense of unwanted methane formation, which takes place predominantly at the (111) facet.3 The surface of the nanocubes was decorated with Au nanoparticles by a galvanic replacement reaction. HAADF-STEM images of the catalysts with various Au loadings are shown in Figure 1a-d. After addition of Au nanoparticles, the shape of the Cu2O nanocubes was preserved. However, the Au nanoparticles were highly dispersed at low loadings (1 mol % Au) whereas Au clusters were observed at higher loadings (10 mol % Au). This result was in line with synchrotron X-ray diffraction (XRD) results, whereby the Au(111) reflection appears for the 10Au/Cu2O sample. Besides, the formation of a Au-Cu alloy and CuO phase was confirmed as well. The highly dispersed nature of the Au nanoparticles at low loadings was further established by Au 4f X-ray photoelectron spectroscopy (XPS), whereby a shift towards higher binding energies was observed as compared to the samples with higher Au loadings. The electrocatalytic performance of the catalysts was assessed over a range of potentials in neutral electrolyte (0.1 M KHCO3) in H-cell configuration. With highly dispersed Au as promotor, we found that the formation of ethylene and ethanol was significantly enhanced (Figure 1e-f). More specifically, the Faradaic effiency towards ethanol increased by roughly 1.5 times by introducing 1 mol % Au to the Cu2O nanocubes. Surprisingly, the 10Au/Cu2O sample displayed the lowest Faradaic efficiency for C2 products. We believe that the dispersion of Au on the Cu2O surface plays an important role in the product formation, whereby CO can be formed at Au sites and diffuse to Cu sites in proximity for further reduction to C2 products (CO spillover). To further study structure-activity relationships, we performed in-situ X-ray absorption spectroscopy (XAS) measurements. Figure 1g shows the normalized Cu K-edge X-ray absorption near-edge structure (XANES) of the Cu2O and Au/Cu2O samples in the final state. The evolution of the Cu(0), Cu(I) and Cu(II) fractions was followed by Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis. This analysis revealed that the final oxidation state of the catalysts is different. The Cu(I)/Cu(0) ratio shows the following trend 1Au/Cu2O > 5Au/Cu2O > Cu2O > 10Au/Cu2O. Based on these observations, we hypothesize that the oxidation state of Cu affects the product distribution and in particular, the formation of oxygenates. The presence of Cu(I) species and the formation of Cu(0) species during CO2 electroreduction was further confirmed with in-situ XRD measurements. Finally, we performed quasi in-situ XPS measurements to study the reduction of the surface of the catalysts. Acknowledgements This publication is part of the research programme 'Reversible Large-scale Energy Storage' (RELEASE) with project number 17621 which is financed by the Dutch Research Council (NWO).

Corrosive behavior of copper canisters under air and aerobic groundwater at early stages of deep geological disposal

Copper oxidation at low temperatures below 140 °C and its effects on corrosive behavior in aerobic groundwater are investigated to estimate the intactness of canisters at early stages of disposal. The Cu coupon surface is covered by fine particles that form thin oxide layers after 30 d of oxidation; a thin Cu2O layer of thickness <100 nm is formed after oxidation at 40 °C; after oxidation at 140 °C, the Cu2O surface changes to a CuO layer of thickness <500 nm. The thickness of the Cu surface oxidized at 90 °C is between those of the surfaces oxidized at 40 and 140 °C. All Cu coupons exhibit similar current densities ranging from 0.77 to 1.87 μA cm−2, although the corrosion potential of the Cu coupon layered with Cu2O is higher than that of the others. Long-term oxidation tests for 406 d reveal no significant changes in the Cu surface at temperatures below 90 °C, indicating no significant change in the electrochemical behavior. The results of this study suggest that the storage of canisters at temperatures below 90 °C has no significant effect on the degradation of canister performance in long-term disposal.

Microwave‐assisted synthesis of 1,4‐disubstituted 1,2,3‐triazole derivatives utilizing NiO/Cu2O nano‐photocatalyst

AbstractBACKGROUNDThe main characteristic features of nickel–copper‐catalyzed azide–alkyne click (Ni‐CuAAC) reactions for production of 1,2,3‐triazoles are regioselectivity and the reaction proceeding under mild conditions. The use of copper salts as catalysts often leads to challenges like contamination of the prepared triazoles. NiO/Cu2O nanocomposites (NCs) were utilized in Ni‐CuAAC reactions as heterogeneous nanocatalysts to achieve the production of some 1,4‐disubstituted 1,2,3‐triazoles in high chemical yields under microwave irradiation.RESULTSThe preparation of NiO/Cu2O NCs was performed through the coprecipitation of NiO nanoparticles on Cu2O surface. The prepared catalyst was used for catalyzing a reaction between benzoyl azides and phenylacetylene under optimized reaction conditions. The NiO/Cu2O NCs exhibited high catalytic activity compared to Cu2O nanoparticles. In addition, by utilizing ethanol–water as the solvent system under microwave irradiation, higher yields and efficient product separation were observed.CONCLUSIONThis study investigated the proficiency of NiO/Cu2O NCs as effective nanocatalysts for the selective synthesis of some 1,4‐disubstituted 1,2,3‐triazole derivatives. Employing heterogeneous nanoparticle catalysts, such as Cu2O and NiO/Cu2O, offers several advantages over homogeneous catalytic systems. These include easier catalyst separation and recovery, potential for catalyst reuse and the ability to fine‐tune the catalytic properties by modulating the nanoparticle composition and structure. © 2024 Society of Chemical Industry (SCI).

Cu Regulating the Bifunctional Activity of Co-O Sites for the High-Performance Rechargeable Zinc-Air Battery.

The rational design of cost-effective and highly active electrocatalysts becomes the crucial energy storage technology to boost the kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), which hinders the large-scale application of metal-air batteries under the situation of increasingly pressing energy anxiety. Herein, the Co-based ZIF introduced the moderate amount of Cu2+-derived Cu/Co metal nanoparticles (NPs) embedded in carbon frameworks after high-temperature calcination. The Co-O bond on the surface of Co nanoparticles is modulated by adjacent Cu nanoparticles with the surface Cu-O bonds. The resulted increase of the Co2+/Co3+ ratio in 0.1CuCo-NC enhances the ORR/OER bifunctional catalytic kinetics along with the ΔE of 0.639 V. In situ Raman spectra of the catalyst on the three-electrode system as well as in the driven zinc-air battery (ZAB) show that the Co-O active sites regulated by Cu nanoparticles with Cu-O bonds maintain a periodic lattice expansion and compression during discharging and charging. The zinc-air battery based on 0.1CuCo-NC has a peak power density of up to 198.3 mW cm-2, a mass-specific capacity of 798.2 mAh g-1, and a cycling stability of 923 h at room temperature. This work makes up the research gap of a Co-based metal-organic framework (MOF)-derived catalyst regulated by a transition metal.

Evolution of copper ions in nanostructured Cu[formula omitted]O according to X-ray absorption spectroscopy data

Soft X-ray absorption spectroscopy (Cu L and O K spectra ) was applied to identify changes in the charge states of copper ions in quasi-statically loaded (torsion under pressure) Cu2O. As was found from our X-ray diffraction and X-ray absorption experiments, an increase in the degree of deformation lead to a decrease in the areas of coherent scattering (sizes of nanograins), to partial amorphization of oxides, and to a slight increase in the concentration of Cu2+ ions on the surface of the Cu2O samples. No new phases were detected using X-ray diffraction measurements. The repeated measurements of the Cu L and O K spectra of the nanostructured Cu2O samples after two years showed significantly more intense signals at high photon energies, indicating the appearance of Cu2+ ions on the surface of nanostructured Cu2O, corresponding to the CuO phase. It was shown that two types of Cu2+ ions on the surface of Cu2O samples with different binding energies of Cu 2p electrons could be formed.

Accelerating alcohol oxidation kinetics for electrochemical biomass upgrading via photoinduced active CuIII-O generation

Copper-based compounds exhibit broad prospects in the electrocatalytic oxidation of biomass for sustainable production of high-value-added chemicals due to their passivated oxygen evolution reaction (OER) competitiveness. However, the sluggish reaction kinetics remain the main challenge in constraining their scalable application. Herein, a highly selective electrooxidation of 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) on CuO is achieved via photoinduced surface reconstruction. The experimental results confirmed that the photogenerated hole accumulation on the surface of CuO with matched valence band position can promote the CuOOH active phase generation. Density functional theory (DFT) calculations and the overall relationship between structure and selectivity indicate the CuOOH species can accelerate the spontaneous dehydrogenation process of hydroxyl group. Therefore, the activated CuO electrode under illumination can effectively regulate the conversion of 5-Hydroxymethyl-2-furancarboxylic acid (HMFCA) key intermediates and exhibits accelerated reaction kinetics, FDCA yield increased by 17.79 % compared to dark condition. Additionally, a general enhancement effect on the oxidation of benzyl alcohol and furfuryl alcohol was also revealed. This work introduces photoassistance effect for the first time in HMF oxidation, opening up prospects for the application of photoelectric synergy in biomass value-added conversion and providing insights into the activity mechanism of Cu-based catalysts in organic oxidation.

Sonochemical synthesis of S-scheme CuO/CeO2 heterojunction for enhanced photocatalytic degradation of rhodamine B dye under solar radiations

CeO2 is renowned photocatalyst with 2.8 eV band gap energy and exceptional optical features. However, the slow charge transportation and the fast recombination of the electron-hole pair hindered the photocatalytic efficiency. In this pioneering research, S-scheme CuO/CeO2 heterojunctions were engineered sonochemically with rational compositions of CeO2 and CuO nanoparticles for enhanced the photocatalytic efficiency of CeO2 in destructing rhodamine B dye under full solar radiations. Diffuse reflectance spectrum [DRS], photoluminescence [PL], high resolution transmission electron microscope [HRTEM], selected area electron diffraction [SAED], N2-adsorption-desorption isotherm, X-ray photoelectron spectroscopy [XPS] and X-ray diffraction [XRD] investigated the physicochemical properties of CuO/CeO2 heterojunction. Monoclinic CuO nanoparticles of 8 nm size are facilely incorporated in cubic CeO2 crystallites of 27.3 nm through substitution of Ce4+ by Cu2+ ions which ascribed to smaller ionic radii of Cu2+ compared with Ce4+ and Ce3+ ions. Homogeneous distribution of CuO nanoparticles on CeO2 surface was further investigated by SEM and TEM analysis. HRTEM, XRD, SAED and XPS analysis recorded the co-existence of crystalline peaks of CeO2 and CuO implying the successful construction of CuO/CeO2 heterojunction. The depression in the surface area of CeO2 from 91.4 to 83.6 m2/g with incorporating 5 wt % of CuO revealed the deposition of CuO on CeO2 surface. XPS analysis implied the existence of Ce3+ and oxygen vacancies that provide more adsorption sites for oxygen, which are beneficial for enhancing the catalytic performance of catalysts. CuO nanoparticles with 1.3 eV band energy enhanced the visible light absorbability of the heterojunctions in deep visible region for broading the photocatalytic response. Significant reduction in photoluminescence signals intensity by 60 % with incorporation 5 wt % of CuO revealed the favorable reduction in the rate of electron-hole recombination. In particular, CeCu5 containing 5 wt % CuO expelled 96 % of RhB dye within 6-h under solar simulator compared with 13 % removal on pristine CeO2 and CuO surface. Hot radicals and positive holes degraded RhB dye molecules on the heterojunction surface as elucidated from scavenger experiments and PL analysis of terephthalic acid. The exceptional removal of RhB dye under solar radiation was ascribed to the alignment in the band structure of CeO2 and CuO nanoparticles and the successful production of an efficient S-scheme heterojunction with strong redox potential and better electron transportation and separation.

Modulating surface chemistry of copper oxides through annealing environment for enhanced selective HMF oxidation: A DFT-electrochemical approach

A comprehensive study was reported to address the effects of both copper (I) and copper (II) oxides on the electrocatalytic 5-hydroxymethylfurfural (HMF) oxidation reaction. Cu2O (1 1 1) demonstrated an outstanding selectivity (80 %) and product yield in the oxidation process towards 2,5-diformylfuran (DFF). The recorded current density of 0.12 mA/cm2 for Cu2O-dominated sample was doubled comparing to its counterpart electrocatalyst, CuO, under mild pH 9.6 condition. Periodic density functional theory calculations show that the higher DFF selectivity for the Cu2O dominant catalyst can be explained by the Cu2O (1 1 1) surface being more oxyphilic while being less carbophilic than the CuO (1 1 1) surface. As a result, all the reaction intermediates that lead to DFF are stabilized significantly more than those that lead to other products. This work deepens the understanding of copper-based oxide material for the HMF electrooxidation and provides a new window for designing electrocatalyst.

Stable detection of diazinon residues in vegetables by an electrochemiluminescent aptasensor based on the in-situ production of H2O2 from dual-catalytic glucose

Stable detection of diazinon (DZN) residues in vegetables is important for food safety. In this work, an electrochemiluminescence (ECL) aptasensor with dual-catalytic glucose in-situ production of H2O2 was constructed for the stable detection of DZN in vegetables. Firstly, MWCNTs@MB was prepared using π-π stacking interactions between methylene blue (MB) and multi-walled carbon nanotubes (MWCNTs) to enhance the loading of MB on an electrode and thus catalyze the generation of H2O2 from glucose. Secondly, Cu2O@AuNPs was formed by loading AuNPs on the surface of Cu2O through spontaneous reduction reaction, which improved the interfacial charge transfer, Cu2O nano-enzyme had glucose oxidase mimicking activity and could further catalyze the production of more H2O2 from glucose. MWCNTs@MB and Cu2O@AuNPs played a key role in the in-situ generation of co-reacting reagent H2O2, which solved the problem of unstable detection caused by the easy decomposition of the H2O2 solution added to the luminescence system. In addition, the aptamer was immobilized on the electrode surface by forming Au–S bonds with Cu2O@AuNPs. As a result, the ECL aptasensor performed good linearity in 1.00 pg mL−1-1.00 μg mL−1 and a low limit of detection (LOD) to 0.39 pg mL−1 (S/N = 3). This work provided an effective method for the accurate and stable detection of DZN residues in vegetables, which was of great significance in ensuring food safety and assessing the environmental risk of DZN.

Formation mechanism of environmentally persistent free radicals during soot aging

Environmentally persistent free radicals (EPFRs) are a newly emerging class of pollutants that are known to be formed on metal oxides (MOs). Recent experimental investigations have suggested that EPFRs may also be formed on soot. However, little is known about the structural and compositional characteristics of soot surfaces conducive to EPFRs formation. Concurrently, the changes in the surface structure and composition of soot indicate its aging process, yet the detailed mechanism underlying EPFRs formation in this process remain obscure. Additionally, it is uncertain whether the formation mechanism of EPFRs on soot differs from that on MOs. In this study, the density functional theory (DFT) and ab initio molecular dynamics (AIMD) were used to investigate EPFRs formation on soot at different stages of aging. The results indicate that EPFRs could be formed on both the complete soot surface with hydroxyl groups and the defective surface. Correspondingly, during the aging process of soot, the formation trend of EPFRs increases in the early stage of the aging process and then decreases over time. Additionally, the formation mechanism on soot is different from that on CuO. On soot, the EPFRs formation is initiated by free hydroxyl radical formed through the desorption process, following the Eley-Rideal mechanism, while on CuO surfaces, its formation involves the surface-bound hydroxyl groups, and thus follows the Langmuir-Hinshelwood mechanism. Furthermore, EPFRs triggered by soot are less stable than those by CuO, due to the easier desorption process of phenoxyl radicals on soot. These findings provide valuable insights into the detailed formation mechanism of EPFRs on soot at different stages of aging, thereby contributing to control EPFRs emissions from a mechanism perspective.

Effects of Curing Agents on the Adhesion of Epoxy Resin to Copper: A Density Functional Theory Study.

Epoxy resins are widely used adhesives in industrial fields. To use epoxy resin as an adhesive, it is necessary to mix the epoxy resin with a hardener. Hardeners have various functional groups and skeletons, and the properties of epoxy resins vary depending on the hardener. Although the adhesion of epoxy resins has been extensively studied using density functional theory (DFT) calculations, few studies have evaluated the effect of hardener molecules. Therefore, in this study, DFT calculations of adhesion energies and bonding structures on Cu (111) and Cu2O (111) surfaces are performed for model molecules of adducts of epoxy resin with hardeners having various functional groups and skeletons to evaluate the influence of the hardeners on the adhesion of epoxy resin to the metal surface. The adhesion energy to the Cu (111) surface is governed by the energy due to dispersion forces. Hardeners of the thiol type, which contain relatively heavy sulfur atoms, and hardeners with aromatic rings, displaying high planarity, enable the entire molecule to approach the metal surface, resulting in a relatively high adhesion strength. The calculations for the Cu2O (111) surface show the adhesion strength is more strongly influenced by interactions such as hydrogen bonds between the surface and adhesive molecules than by dispersion forces. Therefore, in adhesion to Cu2O (111), the benzylamine-epoxy adduct with hydrogen bonding and OH-π interactions with the surface, in addition to having a relatively flexible framework, shows a high adhesion strength.

First-Principles Study on the Structural and Magnetic Properties of Low-Index Cu2O and CuO Surfaces

First-Principles Study on the Structural and Magnetic Properties of Low-Index Cu₂O and CuO Surfaces

Removal of radioactive iodine by Cu2O prepared with PVP as an active agent: Role of crystal facets and oxygen vacancy in adsorption mechanisms

Radioactive iodine removal continues to pose significant challenges. In this study, the advantages of crystal facet and defect engineering were utilized to synthesize six types of Cu2O nanocrystals with varying crystal facet exposed, crystal edge exposed, and abundant oxygen vacancies (OVs). Compared to pure {100} and {111} exposed Cu2O, {100}+{111} co-exposed Cu2O exhibited superior adsorption capacity and adsorption rate for iodide ions (I−), achieving a removal efficiency of 96 % for trace I− (0.1 mg/L). Moreover, OVs significantly contribute to iodide ion (I−) adsorption. Experimental and density functional theory (DFT) analyses confirmed that the active sites on {100}/{111} crystal edges possess the highest affinity for I−. The OVs disrupts the charge balance of the Cu2O surface and increases unsaturated coordination sites of Cu, therefore, it significantly enhanced the affinity for I−. This research offers insights into the design of effective I− adsorption materials using crystal facet and defect engineering strategies.

Mesoporous Cu2O microspheres for highly efficient C2 chemicals production from CO2 electroreduction

Production of C2 chemicals (such as C2H4, C2H5OH, etc.) from CO2 electroreduction reaction (CO2ER) has been regarded as a promising route to solve the environmental problems and energy crisis. In this work, mesoporous Cu2O microspheres of ca. 700 nm diameter size with low crystallinity were fabricated to enable efficient conversion of CO2 to C2 chemicals by electrocatalytic reduction. It is revealed that compared with bulk Cu2O, the obtained mesoporous Cu2O microspheres have larger surface area, more grain boundaries and defects (unsaturated coordination sites), which facilitate the adsorption and stabilization of the important intermediates, such as *CO, on the route to C2 chemicals formation. As a result, the Faraday efficiency (FE) of C2 products reaches as high as 82.6 % and 78.5 % in an H-cell and a flow cell, respectively. In situ Raman and FT-IR spectra reveal that during CO2ER test there exists abundant *CO on the mesoporous Cu2O surface, thus increasing the opportunity of CC coupling. And the high coverage of *CO on catalyst surface during CO2ER protects and stabilizes the oxidation state of Cu species. This work demonstrates an effective strategy to introduce mesoporous structures and decreased crystallinity for improving the performance of CO2ER to C2 products.