Mesoporous Copper Oxide Research Articles

Gas-Phase Pd Clusters-Modified Mesoporous Copper Oxide Hollow Spheres As Electrocatalysts for CO2 Reduction to Ethylene

Renewable energy-driven electrochemical CO2 conversion to value-added chemicals is a prospective strategy for addressing global carbon emission and energy consumption issues worldwide. Until today, only copper-based electrocatalysts can successfully transform CO2 into C2H4 or other desirable C2+ products, but their stability and product selectivity remain insufficient.1 Oxide-derived Cu mesoporous foam catalysts currently show the best selectivity toward C2+ product formation at particularly low overpotentials due to the availability of specific surface sites for C−C coupling in their structure and to the temporal trapping of gaseous intermediates inside the mesoporous catalyst material during CO2 electrolysis.2 To further improve their stability and product selectivity their surface can be modified with metallic clusters that can promote the adsorption of CO2 and the subsequent formation of intermediates. In particular, Pd clusters provide a favorable surface for the initial adsorption of CO2,3 while inducing a continuous restructuring of the Cu surface that maintains its catalytic properties for CO2 reduction to hydrocarbons.4 Herein, we report a novel highly efficient electrocatalyst for CO2 conversion in C2+ products based on mesoporous oxygen-rich copper hollow spheres prepared by a colloid templating method, whose surface is uniformly modified by the deposition of different loadings of well-defined Pd clusters of ca. 3 nm diameter using the laser ablation cluster beam deposition (CBD) technology.5 Primary electrochemical results show that these electrodes are able to reduce CO2 to ethylene with a faradaic efficiency of more than three times higher than that of commercial Cu2O nanoparticles under the same reaction conditions. A clear phase transition from CuO to Cu2O and metallic Cu is occurring under CO2 electro-reduction conditions as highlighted by XRD.These remarkable performances are likely originating from the facile gas charge transport via the mesoporous structure of the oxygen-rich copper spheres as imaged by SEM (Figure 1) as well as from their high surface area, which allows a high catalytic activity and a uniform accommodation of the metallic clusters.As CBD is a versatile technique that allows the deposition of virtually any type of well-defined cluster on a large variety of support, this work provides an attractive avenue to achieve stable selective multicarbon products via rational electrode design. References Kuhl KP, et al., Energy and Environmental Science, 2012;5 (5):7050-7059.Abhijit Dutta, et al., ACS Catal. 2016, 6, 3804−3814Sichao Ma, et al., J. Am. Soc. 2017, 139, 47−50Zhe Weng, et al., Angew. Int. Ed. 2017, 56, 13135 –13139Chinnabathini V. C., et al., Nanoscale, 2023, DOI: 10.1039/D2NR07287D. Figure 1

Vesicular mesoporous copper oxide as anode for high lithium storage

Vesicular mesoporous copper oxide as anode for high lithium storage

Synthesis and characterization of a high-performance enzyme-free glucose sensor based on mesoporous copper oxide nanoparticles

Mesoporous copper oxide were prepared and characterized as a non-enzymatic glucose sensor. Scanning electron microscopy, X-ray diffraction and surface adsorption analysis were used to analyze the samples. Considering the normal glucose levels, the CV measurements were conducted for glucose concentrations ranging from 1 to 9 mM. Accordingly, nanoparticles with particle sizes less than 100 nm showed a desired linear response for glucose detection in the 1 to 9 mM concentration range. Also, it exhibited a reasonable detection limit of 0.05 μM and a high sensitivity of 733 μAmM−1cm−2 in the alkaline pH range. Furthermore, a relatively good sensitivity for glucose detection in phosphate buffer solution (pH 7.4) was also observed. The optimum detection performance could be attributed to the improvement of the particles size, morphology and pore structure. It was concluded that mesoporous copper oxide nanoparticles have desirable potential functionalities for enzyme-free glucose detection.

Enhanced adsorption of ceftriaxone antibiotics from water by mesoporous copper oxide nanosphere

Enhanced adsorption of ceftriaxone antibiotics from water by mesoporous copper oxide nanosphere

Aluminum-Doped Mesoporous Copper Oxide Nanofibers Enabling High-Efficiency CO2 Electroreduction to Multicarbon Products

Copper is the most promising catalyst for the electrocatalytic conversion of CO2 into multicarbon (C2+) products but it is often plagued by low selectivity and productivity. Here, we report that aluminum (Al)-doped mesoporous copper oxide nanofibers (Cu-Al MONFs) can exhibit excellent performance in the electrocatalytic reduction of CO2 to C2+ products, with the remarkable C2+ Faradaic efficiency of 76.4% at a high current density of 600 mA cm–2. In sharp contrast, the comparative CuO nanofibers exhibit extremely severe hydrogen evolution (FE up to ∼70%) and limited C2+ products under the same condition. Detailed investigations indicate that the introduction of Al not only induces the formation of a mesoporous structure during the etching process but also adjusts the electronic structure of Cu via doping, which optimize the intermediate binding and C–C coupling on the Cu-Al MONFs. This work provides new inspiration for exploring high-performance Cu-based materials for electrocatalytic reduction of CO2.

Mesoporogen free synthesis of CuO/TiO2 heterojunction for ultra-trace detection of catechol in water samples

Creating mesoporous architecture on the surface of metal oxides without using pore creating agent is significant interest in electrochemical sensors because these materials act as an efficient electron transfer process between the electrode interface and the analytes. Recent advances in mesoporous titanium dioxide (TiO2)-based materials have acquired extraordinary opportunities because of their interconnected porous structure could act as a host for doping with various transition metals or heteroatoms to form a new type of heterojunction. Herein, a simple method is developed to synthesize mesoporous copper oxide (CuO) decorated on TiO2 nanostructures in which homogenous shaped CuO nanocrystals act as dopants decorated on the mesoporous structure of TiO2, resulting in p-n heterojunction nanocomposite. The TiO2 particles exhibit a mesoporous structure with a pore volume of about 0.117 cm3/g is capable to load CuO nanocrystals on the surface. As a result, large pore volume 0.304 cm³/g is obtained for CuO–TiO2 heterojunction nanocomposite with the loading of uniform-shaped CuO nanocrystals on the mesoporous TiO2. The resulting CuO–TiO2 nanocomposite on modified glassy carbon (GC) electrode exhibits good electrochemical performance for oxidation of catechol with the observation of strong enhancement in the anodic peak potential at +0.36 V. The decrease in the overpotential for the oxidation of catechol when compared to TiO2/GC is attributed to the presence of CuO nanocrystals providing a large surface area, resulting in wide linear range 10 nM to 0.57 μM. Moreover, the resultant modified electrode exhibited good sensitivity, selectivity and reproducibility and the sensor could able to determine the presence of catechol in real samples such as lake and river water. Therefore, the obtained CuO–TiO2 nanocomposite on the modified GC delivered good electrochemical sensing performance and which could be able to perform a promising strategy for designing various metal oxide doped nanocomposites for various photochemical and electrocatalytic applications.

Synthesis, characterization and non-enzymatic lactate sensing performance investigation of mesoporous copper oxide (CuO) using inverse micelle method

Lactate biosensors based on enzymes have been widely studied. However, they have limitations including low reliability, owing to biological degradation, and high cost. Therefore, transition metal oxides have been extensively investigated for non-enzymatic biosensors owing to their electrochemical catalytic properties and good stability. In this study, we synthesized mesoporous copper oxides (CuOs) by the inverse micelle sol-gel process and fabricated a lactate biosensor using mesoporous CuOs as the electrode material. It is difficult to synthesize mesoporous CuO using the inverse micelle method because Cu has more polymeric hydrolysis species under the same condition than other transition metals. Therefore, we controlled the formation of the polymeric hydrolysis species by setting the precursor and acid concentrations. The primary phase of copper oxalate hydrate was synthesized, and phase transformation to CuO with mesoporosity was achieved through heat treatment. The characteristics of the mesoporous CuO were analyzed by X-ray diffraction, N2 sorption isotherms, and transmission electron microscopy. Mesoporous CuO with a large specific surface area of 166.03 m2/g was successfully synthesized after heat treatment at 250 °C. The non-enzymatic lactate sensing characteristics were assessed using an amperometric response with a three-electrode system. The mesoporous CuO-based biosensor exhibited a maximum sensitivity of 80.33 μA/mM.

"Ghost" Silica Nanoparticles of "Host"-Inherited Antibacterial Action.

We fabricated surface-rough mesoporous silica nanoparticles ("ghost" SiO2NPs) by using composite mesoporous copper oxide nanoparticles ("host" CuONPs) as templates, which allowed us to mimic their surface morphology. The "host" CuONPs used here as templates, however, had a very high antibacterial effect, with or without functionalization. To evaluate the surface roughness effect on the "ghost" SiO2NPs antibacterial action, we functionalized them with (3-glycidyloxypropyl)trimethoxysilane (GLYMO) to permit additional covalent coupling of 4-hydroxyphenylboronic acid (4-HPBA). The diol groups on the bacterial membrane can form reversible covalent bonds with boronic acid (BA) groups on the "ghost" SiO2NPs surface and bind to the bacteria, resulting in a very strong amplification of their antibacterial activity, which does not depend on electrostatic adhesion. The BA-functionalized "ghost" SiO2NPs showed a very significant antibacterial effect as compared to smooth SiO2NPs of the same surface coating and particle size. We attribute this to the "ghost" SiO2NPs mesoporous surface morphology, which mimics to a certain extent those of the original mesoporous CuONPs used as templates for their preparation. We envisage that the "ghost" SiO2NPs effectively acquire some of the antibacterial properties from the "host" CuONPs, with the same functionality, despite being completely free of copper. The antibacterial effect of the functionalized "ghost" SiO2NPs/GLYMO/4-HPBA on Rhodococcus rhodochrous (R. rhodochrous) and Escherichia coli (E. coli) is much higher than that of the nonfunctionalized "ghost" SiO2NPs or the "ghost" SiO2NPs/GLYMO. The results indicate that the combination of rough surface morphology and strong adhesion of the particle surface to the bacteria can make even benign material such as silica act as a strong antimicrobial agent. Additionally, our BA-functionalized nanoparticles ("ghost" SiO2NPs/GLYMO/4-HPBA) showed no detectable cytotoxic impact against human keratinocytes at particle concentrations, which are effective against bacteria.

Kinetic and catalytic analysis of mesoporous metal oxides on the oxidation of Rhodamine B

In this study, we demonstrate the synthesis and catalytic activity of different mesoporous transition metal oxides, silica (SiO2), copper oxide (CuO), chromium oxide (Cr2O3), iron oxide (Fe2O3) cobalt oxide (Co3O4), cerium oxide (CeO2) and nickel oxide (NiO), on the oxidation of a pollutant dye, Rhodamine B (RhB). These metal oxides were synthesized by inverse micelle formation method and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), adsorption-desorption isotherms (BET) and H2-temperature programmed reduction (TPR). UV–vis spectrophotometry was used to monitor the time-resolved absorbance of RhB at λmax = 554 nm. Mesoporous copper oxide was calcined at different final heating temperatures of 250, 350, 450 and 550 °C, and each mesoporous copper oxide catalyst showed unique physical properties and catalytic behavior. Mesoporous CuO-550 with the smallest characteristic path length δ, proved to be the catalyst of choice for the oxidation of RhB in aqueous media. We observed that the oxidation of RhB in aqueous media is dependent on the crystallite size and characteristic path length of the mesoporous metal oxide. The Langmuir-Hinshelwood model was used to fit the experimental data and to prove that the reaction occurs on the surface of the mesoporous CuO. The thermodynamic parameters, EA, ΔH#, ΔS# and ΔG# were calculated and catalyst recycling and reusability were demonstrated.

Magnetic Nanospheres Encapsulated by Mesoporous Copper Oxide Shell for Selective Isolation of Hemoglobin.

A novel strategy for the preparation of magnetic nanospheres encapsulated by mesoporous copper oxide shell, shortly termed as Fe3O4@mCuO, is reported via the calcination of Cu(NH3)4(NO3)2 into continuous mesoporous CuO shell onto the surface of Fe3O4 nanoparticles. The magnetic nanospheres are characterized to possess stable core-shell structure with a crystalline mesoporous CuO layer, exhibiting a CuO loading content of 25.2 ± 1.1% along with a favorable magnetic susceptibility. Fe3O4@mCuO nanospheres exhibit favorable selectivity on the adsorption of hemoglobin with a high adsorption capacity of up to 1162.5 mg g-1. After adsorption, the high magnetic susceptibility allows convenient separation of the nanospheres by an external magnet. The retained hemoglobin could be readily recovered by using 0.5% (m/v) sodium dodecyl sulfate (SDS) as stripping reagent, providing a recovery of 78%. Circular dichroism spectra illustrate virtually no change in the conformation of hemoglobin after the process of adsorption/desorption. Fe3O4@mCuO nanospheres are further applied for the selective isolation of hemoglobin from human whole blood, achieving high-purity hemoglobin as demonstrated by SDS-PAGE (polyacrylamide gel electrophoresis) assays.

Ordered mesoporous copper oxide nanostructures as highly active and stable catalysts for aqueous click reactions

We demonstrate that ordered mesoporous CuO with gyroid mesostructures can be used as highly efficient, stable, and recyclable self-supported catalysts for click reactions in aqueous media.

Study on the oxidation of vanillymandelic acid to vanillin over mesoporous copper oxide

Mesoporous CuO synthesized by the hydrothermal method was used as a catalyst for the oxidation of vanillymandelic acid to vanillin with molecular oxygen as the terminal oxidant for the first time. The effects of reaction conditions on the catalytic performances have been investigated in detail, almost 100 % conversion of vanillymandelic acid and 88.3 % yield of goal product were achieved under the best conditions of reaction time 6 h, oxygen pressure 0.45 MPa, 85 °C and pH 12.5. In addition, the mesoporous CuO revealed outstanding recyclability and exhibited several pivotal advantages, including mild reaction conditions, environmentally friendly oxidant, as well as greatly reduced the amount of catalyst. A plausible mechanism for the liquid-phase oxidation of vanillymandelic acid on CuO was proposed.

PdCl2-loading mesoporous copper oxide as a novel and environmentally friendly catalyst for diethyl carbonate synthesis

PdCl2-loading mesoporous copper oxide (PdCl2/mCuO) catalysts were successfully synthesized via a hard template with copper carbonate basic (Cu2(OH)2CO3), cupric nitrate (Cu(NO3)2·3H2O) and copper citrate (Cu2C6H4O7·2.5H2O) as the copper(II) precursors, respectively. Their catalytic performances were investigated in the synthesis of diethyl carbonate (DEC) by oxidative carbonylation of ethanol with CO and O2. The catalysts were characterized by TGA, XRD, nitrogen adsorption–desorption analysis and SEM with the aim of establishing their composition, morphology and structure. It was observed that the catalysts all showed a good selectivity to diethyl carbonate. However, due to a better mesoporous structure such as a bigger surface area, more uniform particle size and less agglomeration, the PdCl2/mCuO-1 catalyst prepared with Cu2(OH)2CO3 precursor showed a better catalytic activity that the conversion of EtOH was about 4.8% and the STY of DEC was 97.1mgg−1h−1. This was because the highly developed mesoporous structure could generate a bigger surface area, which benefited the contact between reactants and active sites, improved the conversion of ethanol, and thus enhanced the catalytic performance. Furthermore, a synthetic procedure diagram about “wet impregnation” method of mesoporous CuO prepared with Cu2(OH)2CO3 precursor was given to illustrate these results intuitively.

Magnificent adsorption capacity of hierarchical mesoporous copper oxide nanoflakes towards mercury and cadmium ions: Determination of analyte concentration by DPASV

Hierarchical mesoporous copper oxide nanoflakes (CuOs) were successfully synthesized by hydrothermal method. The complete characterization of product was done by XRD, SEM, TEM, SAED, EDX, BET and FT-IR studies. The batch experiments were conducted under different adsorbate concentration, contact time, pH and temperature conditions. The residual analyte concentration was determined using differential pulse anodic stripping voltammetry (DPASV) technique with high accuracy and reproducibility. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. Equilibrium data were best fitted with the Langmuir and Freundlich isotherm models and the maximum adsorption capacities of Hg(II) and Cd(II) were determined to be 1767.97 and 1577.78mg/g respectively. All these values are significantly higher than those reported on other hierarchical nanostructures. Thermodynamic parameters and adsorption kinetics were studied in detail to know the nature and mechanism of adsorption. A regeneration study is proposed in order to reuse the adsorbent for better economy of the process. The results demonstrate that CuOs can be used as a possible alternative low-cost adsorbent for the efficient removal of heavy metals from aqueous solutions.

Hierarchically macro/mesostructured porous copper oxide: facile synthesis, characterization, catalytic performance and electrochemical study of mesoporous copper oxide monoliths

Hierarchically macro/meso structured porous copper-oxide monoliths with and without additives (dextran, 1,3,5-trimethylbenzene and silica nanoparticles) were successfully synthesized via a facile sol–gel route.

Mesoporous Copper Oxide as a New Combustion Catalyst for Composite Propellants

The use of powder additives to modify the burning rates of solid propellants and other energetic materials has been the topic of much study for several decades. This paper reports the discovery of the enhancement of the performance of ammonium perchlorate-based composite propellants by means of employing mesoporous copper oxide powder as a new burning rate catalyst in comparison to conventional (nonporous) copper oxide fillers. The burning rate measurements, obtained by the strand burner method, show that, with the addition of mesoporous fillers of copper oxide in aluminized composite propellants, higher rates (in excess of at 7 MPa) are found over a broad pressure range. It was noticed that these high burning rates were accompanied by a more stable combustion, decreasing considerably the pressure index (0.40 versus 0.55). The thermal characterization of these highly energetic composite materials was also carried out by differential scanning calorimetry and thermogravimetric analysis, demonstrating that the incorporation of mesoporous copper oxide particles in the formulations improves their combustion behavior, shifting the temperature decomposition peak toward a lower temperature and decreasing the activation energy. The results presented here reveal the advantages exhibited by the use of these mesoporous particles as an additive for solid rocket propulsion technology.

Synthesis of mesoporous copper oxide microspheres with different surface areas and their lithium storage properties

We report the comparative investigation on the electrochemical application of mesoporous copper oxide (Cu2O and CuO) microspheres with different surface areas as anode materials in Li-ion batteries. Mesoporous Cu2O microspheres with a narrow particle size distribution are synthesized by a hydrothermal method and CuO is obtained by subsequent oxidation of Cu2O. The synthesized mesoporous Cu2O and CuO microspheres possess a surface area of 12.7–65.8 and 5.2–37.6 m2 g−1 and an average crystal size of 15.0–20.5 and 10.4–15.9 nm, respectively. The result reveals that the mesoporous Cu2O and CuO microspheres with a higher surface area show a higher capacity and better cyclability than those with a lower surface area. The mesoporous Cu2O and CuO microspheres with a surface area of 65.8 and 37.6 m2 g−1 show an initial charge capacity of 430.5 mAh g−1 and 601.6 mAh g−1 and deliver a capacity as high as 355.2 mAh g−1 and 569.8 mAh g−1 at 0.1 C after 50 cycles, respectively. This is because the highly developed mesoporous structure can enhance the accommodation of lithium ions, shorten the diffusion distance for lithium ions, and increase the absorption of electrolyte.

Structure and optical properties of ordered mesoporous copper oxide–silica composite films

In this study, ordered mesoporous copper oxide–silica (CuO–SiO2) composite films with CuO/SiO2 molar ratio ≤6% have been prepared. Small-angle X-ray diffraction and transmission electron microscopy investigations show that the mesoporous CuO–SiO2 composite films have a hexagonally ordered pore array nanostructure. Wide-angle X-ray diffraction analysis reveals that the copper oxide and silica in the composite films are non-crystalline. The non-crystalline CuO in the mesoporous composite films has an obvious blue-shift phenomenon of the absorption edge. The calculated band gap energy for CuO is 3.2 eV, which is much higher than its bulk counterparts (1.21–1.5 eV).

Synthesis of a Low-Density Copper Oxide Monolithic Aerogel Using Inorganic Salt Precursor

Copper oxide monolithic aerogel was prepared by sol–gel method using inorganic salt as precursor, ethanol as the solvent, and propylene oxide as the gelation agent. Calcination of the as-prepared aerogels at different temperatures induced a phase change which resulted in the formation of a mesoporous copper oxide aerogels. Field emission scanning electron microscopy (FESEM), Highresolution transmission electron microscopy (HRTEM), and Brunauer-Emmett-Teller(BET) methods were used to characterize the as-prepared aerogels. The combined results indicated that the as-prepared CuO aerogel has high porosity, high surface area, and low density. The X-ray diffraction (XRD) patterns show that the as-prepared CuO aerogel is highly crystalline and is identified to be predominantly copper chloride hydroxide, Cu2Cl(OH)3。

Preparation, characterization, and electrochemical application of mesoporous copper oxide

Mesoporous CuO was successfully synthesized via thermal decomposition of CuC 2O 4 precursors. These products had ring-like morphology, which was made up of nanoparticles with the average diameter of 40 nm. The electrochemical experiments showed that the mesoporous CuO decreased the overvoltage of the electrode and increased electron transference in the measurement of dopamine.