Spinel CuCo2O4 Research Articles

Cuco2o4 Spinel Supported on Dealuminized Metakaolinite for Partial Glycerol Oxidation

Cuco2o4 Spinel Supported on Dealuminized Metakaolinite for Partial Glycerol Oxidation

Ambient ammonia production via electrocatalytic nitrate reduction catalyzed by a flower-like CuCo2O4 electrocatalyst

The flower-shaped CuCo2O4 spinel catalyst was used for electrochemical nitrate reduction in an electrolyte. Theoretical calculation shows that NO3− can be adsorbed on CuCo2O4 to form the *NOH intermediate, so as to obtain a good yield rate and FE.

Ce-Substituted Spinel CuCo2O4 Quantum Dots with High Oxygen Vacancies and Greatly Improved Electrocatalytic Activity for Oxygen Evolution Reaction.

Exploring effective electrocatalysts for oxygen evolution reaction (OER) is a crucial requirement of many energy storage and transformation systems, involving fuel cells, water electrolysis, and metal-air batteries. Transition-metal oxides (TMOs) have attracted much attention to OER catalysts because of their earth abundance, tunable electronic properties, and so forth. Defect engineering is a general and the most important strategy to tune the electronic structure and control size, and thus improve their intrinsic activities. Herein, OER performance on spinel CuCo2O4 was greatly enhanced through cation substitution and size reduction. Ce-substituted spinel CuCeδCo2-δOx (δ = 0.45, 0.5 and 0.55) nanoparticles in the quantum dot scale (2-8 nm) were synthesized using a simple and facile phase-transfer coprecipitation strategy. The as-prepared samples were highly dispersed and have displayed a low overpotential of 294 mV at 10 mA·cm-2 and a Tafel slope of 57.5 mV·dec-1, which outperform commercial RuO2 and the most high-performance analogous catalysts reported. The experimental and calculated results all confirm that Ce substitution with an appropriate content can produce rich oxygen vacancies, tune intermediate absorption, consequently lower the energy barrier of the determining step, and greatly enhance the OER activity of the catalysts. This work not only provides advanced OER catalysts but also opens a general avenue to understand the structure-activity relationship of pristine TMO catalysts deeply in the quantum dot scale and the rational design of more efficient OER catalysts.

Encapsulation of spinel CuCo2O4 hollow sphere in V2O5-decorated graphitic carbon nitride as high-efficiency double Z-type nanocomposite for levofloxacin photodegradation

In this study, spinel CuCo2O4 (CCO) with a hierarchical hollow sphere morphology was encapsulated in V2O5-decorated ultra-wrinkled graphitic carbon-nitride (VO-UCN) for the first time via a facile glycerol-assisted solvothermal method in the interest of developing a novel high-efficiency double Z-type nano-photocatalyst (denoted as VO-UCN@CCO). The remarkable physicochemical features of the as-prepared nano-photocatalysts were verified using diverse characterization techniques including TGA, XRD, FT-IR, FE-SEM, TEM, BET, UV–vis DRS, PL, EIS, and transient photocurrent techniques. Herein, VO-UCN@CCO nanocomposite was employed for the photodisintegration of levofloxacin (LVOF) antibiotic under visible-light irradiation and the impact of certain operative reaction system variables was explored in an effort to optimize the photocatalytic capability. The 40% loading of CCO in VO-UCN@CCO nanocomposite was found to display maximum photocatalytic performance (about 95%) for LVOF photodecomposition, which was 9.3, 6.6, and 13.8 times greater when compared with pristine VO, UCN, and CCO, respectively. A high capability was observed for as-prepared photocatalyst during reusability tests and near 90% degradation efficiency was obtained in the sixth run. The complete mineralization of LVOF was achieved by the VO-UCN@CCO photocatalyst process after 300 min of reaction. An excellent synergy factor towards the degradation of LVOF was obtained for VO-UCN@CCO compared to each of its components alone. This peculiar design is envisaged to provide new inspirations for ameliorating the photocatalytic decontamination of tenacious and non-biodegradable species present in real wastewater.

CuCo alloy nanonets derived from CuCo2O4 spinel oxides for higher alcohols synthesis from syngas

Porous CuCo alloy nanonets were used as superior catalysts for higher alcohol synthesis from syngas. The catalyst was fabricated via structural topological transformation of CuCo2O4 spinel precursor.

Facile preparation of the spinel CuCo2O4 Application to hydrogen photo-production

Facile preparation of the spinel CuCo2O4 Application to hydrogen photo-production

Phosphorus‐Doped CuCo2O4 Oxide with Partial Amorphous Phase as a Robust Electrocatalyst for the Oxygen Evolution Reaction

AbstractIt is highly desirable to develop efficient and low‐cost electrocatalysts for the oxygen evolution reaction (OER) to improve the efficiency of water electrolysis. Here, we report a strategy doping with a small amount of phosphorus to make inactive and low‐cost spinel CuCo2O4 (CCO) turn into high‐efficiency and superior to the noble metal catalyst RuO2. The spinel CuCo2O4−P0.5 (CCP0.5) shows the best OER performance with a small overpotential of 290 mV at a current density of 10 mA cm−2 and a low Tafel slope of 68 mV dec−1 in an alkaline electrolyte. The phosphorus doping induces the production of an amorphous phase that provides a large number of active sites, and the synergistic effect of the crystalline phase and amorphous phase significantly improves the OER activity of CCO. It is also revealed that the conductivity of CCO is improved compared with pristine CCO. Our work highlights that non‐metallic element doping is an effective strategy to greatly enhance the OER performance of spinel transition metal oxide electrocatalysts.

Visible light induced H2 evolution on the hetero-junction Pt/CuCo2O4 prepared by hydrothermal route

The photo-electrochemistry of the hetero-junction Pt/CuCo2O4 synthesized by hydrothermal route was studied to assess its ability for the H2 formation under visible light illumination. The X-ray diffraction is characteristic of mixed phases with narrow lines of the spinel CuCo2O4 and Pt. The sensitizer CuCo2O4 has a forbidden band (Eg) of 1.30 eV, well suited to the sun spectrum and displays p-type behavior. Its conduction band (−0.660 VSCE), deduced from the capacitance – potential (C−2 – E) plot, is more cathodic than the H2O/H2 level (~−0.6 VSCE), thus producing spontaneous H2 evolution under irradiation. The photoelectrons are transferred to Pt clusters, to trigger the water reduction owing to the small H2-over-potential. A quantum conversion yield of 0.65% is obtained under visible light (total flux: 15 mW cm−2, 3.42 × 1018 photons s−1) with H2 evolution rate of ~103 µmol g−1 min−1, higher than that obtained over CuCo2O4 (73 µmol g−1 min−1).

Mesoporous CuCo2O4 rods modified glassy carbon electrode as a novel non-enzymatic amperometric electrochemical sensors with high-sensitive ascorbic acid recognition

A simple, rapid and high stability analytical method development for determination ascorbic acid (AA) is using the glassy carbon electrode (GCE) embellished with mesoporous CuCo2O4 rods as a nonenzymatic amperometric sensor. The mesoporous CuCo2O4 rods were prepared by hydrothermal method adopting NH4F as a surfactant to synthesize triumphantly are employed. The sample is pure spinel CuCo2O4 rods with mesoporous structure. It is excellent electrocatalytic performances for AA is measured by I-t curve. The sensitivity of the mesoporous CuCo2O4 rods sensor is up to 9.482 mA mM−1 cm−2 within linearity range of AA concentration (1–100 μM) and 2.474 mA mM−1 cm−2 within linearity range of AA concentration (100–1000 μM), respectively. The detection limit is down to 0.21 μM with correlation coefficient R2 = 0.99. The CuCo2O4/GCE AA sensor exhibits excellent electrochemical stability, repeatability and selectivity, and actual measurement for vitamin C tablets.

Characterization of CuCo2O4 Prepared by Nitrate Route: Application to Ni2+ reduction under visible light

Ni2+ was reduced by photo-catalysis on the hetero-system p-CuCo2O4 /n-TiO2 under visible light. The spinel CuCo2O4, elaborated by nitrate route, was characterized photo-electrochemically. A direct forbidden band of 1.44 eV was determined from the diffuse reflectance. It exhibits p-type behavior and a conduction band (- 1.11 VSCE) made up of Co3+: eg orbital, more cathodic than the Ni2+ level (-0.68 VSCE). The rate of Ni deposition increases with increasing the spinel dose and peaks for the optimal ratio CuCO2O4/TiO2 (50/50) with 60 % conversion (30 mg L−1) in less than 3 h. This occurred because TiO2 mediates the electron transfer to adsorbed Ni2+ ions. The decrease of the conversion rate on the system CuCo2O4/TiO2 over illumination time is due to the competitive water reduction onto deposited Ni clusters. The in situ photo-deposition of Ni-clusters forms hetero-system CuCo2O4/TiO2/Ni intimately contacted and the H2 formation is highly improved because of the low Ni over-potential. H2-evolution rate of 4.69 μmol min−1 g−1 and a quantum yield of 0.68 % were obtained under a light flux of 2.09 × 1019 photons s−1.

Facile synthesis of CuCo spinel composite oxides for toluene oxidation in air

A series of CCOx (x = 0, 1, 3 and 5) CuCo spinel composite oxides were prepared with different oxalic acid ratio by a facile, time-saving and green grinding-complexation method. The prepared spinel oxides were used to investigate the catalytic oxidation of toluene in air, which is a typical volatile organic compound (VOC). X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), H2-Temperature programmed reduction (H2-TPR) and O2-Temperature programmed desorption (O2-TPD) were used to characterize physicochemical properties of prepared CCOx spinel composite oxides. The characterization results show that Cu cations can dissolve into Co3O4 lattice to form CuCo2O4 spinel oxides. The participation of oxalic acids can more favor formation of CuCo2O4 spinel oxides, which promotes more active Co3+ species exposed on the surface and larger amount of adsorbed active oxygen species on CCOx spinel composite oxides. Meanwhile, larger specific surface area has been obtained for the CCOx spinel oxides. As a result, the low-temperature reducibility and O2 adsorption ability are significantly improved. Under the synergetic effects of above-mentioned factors, CCO3 spinel oxide catalyst exhibits the superior catalytic activity for achieving toluene conversion of 90% at 250 °C. This work indicates that the CuCo spinel composite oxide is a promising candidate for toluene catalytic oxidation in air, and grinding-complexation method provide a green, simple and time-saving way for preparation composite metal oxides.

Highly dispersed copper cobalt oxide nanoclusters decorated carbon nitride with efficient heterogeneous interfaces for enhanced H2 evolution

Photocatalytic reaction refers to a sophisticated heterogeneous catalyzing process. Exploring the interfacial reaction of catalysts will provide insights into efficient artificial photosynthetic system and promote its design. In this study, highly dispersed bimetallic CuCo2O4 nanoclusters decorated g-C3N4 heterojunction photocatalyst was produced by in-situ deposition of 0D CuCo2O4 spinel on the 2D g-C3N4 surface. Compared with CuO or Co3O4 modified g-C3N4, the optimal composite exhibits a significantly higher H2 evolution rate of 4187.6 μmol∙gcat−1∙h−1 with an apparent quantum yield (AQY) of 4.57% under the irradiation of monochromatic light (400 ± 7.5 nm) in the absence of noble metal. As suggested from the results of the photoelectrochemistry characterizations and NH3-temperature programmed desorption (NH3-TPD) analysis, CuCo2O4/g-C3N4 exhibited faster HER kinetics and considerable surface acidity sites, and it facilitated triethanolamine (TEOA) chemisorption and H2 evolution, further highlighting the merits of such mixed-metal compounds. Moreover, the transfer pathway of charge carriers between CuCo2O4 and g-C3N4 heterogeneous interface was demonstrated by photo-degradation of RhB and selective photo-deposition Pt nanoparticles.

Sustainable Hydrogen Generation by Catalytic Hydrolysis of NaBH4 Using Tailored Nanostructured Urchin-like CuCo2O4 Spinel Catalyst

The present study describes the hydrogen production as a future energy source via hydrolysis of NaBH4 catalyzed by urchin-like CuCo2O4 spinel catalyst prepared by urea-assisted hydrothermal synthesis method. The as-synthesized copper–cobalt double hydroxide precursor and the resultant CuCo2O4 spinel were characterized by using various analytical, spectroscopic and microscopic techniques in order to understand their physiochemical and morphological aspects. The detail characterization results confirmed the successful formation of CuCo2O4 spinel phase with urchin-like morphology. The CuCo2O4 spinel catalyst was then tested for its application in hydrogen generation from NaBH4 hydrolysis by performing the reaction using 10 wt% of CuCo2O4 spinel catalyst and 0.5 g NaBH4 at room temperature. The CuCo2O4 spinel catalyst with tailored architecture displayed high catalytic activity with H2 generation rate of 1370 mL min−1 g−1 (1438 mL in 21 min). Major factors affecting the hydrolysis of NaBH4 reaction such as catalyst loading, NaOH concentration and temperature variation was also studied and discussed in detail. Correspondingly, the low activation energy of 22 kJ mol−1 was obtained from the Arrhenius plot and kinetic studies revealed that the hydrolysis of NaBH4 followed first order kinetics. Further, recyclability study of CuCo2O4 spinel catalyst was also performed which displayed good catalytic activity and stability even after five successive recycles. Characterization data of reused catalyst revealed that physiochemical properties of fresh CuCo2O4 spinel catalyst were well-preserved in the reused catalyst as well. Therefore, nanostructured CuCo2O4 spinel can be demonstrated as one of the most efficient, cost effective bimetallic spinel catalyst so far for application in the hydrogen generation.

Higher alcohol synthesis from syngas over xerogel-derived Co-Cu-Al2O3 catalyst with an enhanced metal proximity

To improve metal proximity of Co-Cu-Al2O3 catalyst, xerogel-derived mesoporous Co-Cu-Al2O3 catalysts (CoCuAl-Xe) with various Co:Cu molar ratios (3:1, 2:1, 1:1, 1:2, and 1:3) were prepared by an epoxide-driven sol-gel method and applied to higher alcohol synthesis from syngas. The CoCuAl-Xe catalyst induced the formation of a composite spinel structure containing Co, Cu, and Al. At the optimal Co/Cu ratio, the Cu atoms efficiently substituted the Co2+ ions in Co3O4 to form the CuCo2O4 spinel structure. However, an excess amount of Cu induced segregation of CuO, leading to decreasing Co-Cu proximity. In higher alcohol synthesis from syngas, all the catalysts showed the linear quasi-Anderson Schulz Flory plot of carbon-containing products, which was attributed to the CO insertion mechanism in higher alcohol synthesis. Among the xerogel catalysts, 2Co1CuAl-Xe exhibited the highest CO conversion and higher alcohol yield. The Co-rich CoCuAl-Xe catalyst was disadvantageous in terms of alcohol selectivity because of a lack of CO insertion sites, and the Cu-rich one was disadvantageous in CO dissociation and led to methanol formation. The computational study suggests that high Co-Cu proximity favors CHOH* mechanism for CH* formation and promotes CO insertion reaction. Consequently, it was found that the optimal Co/Cu ratio and high Co-Cu proximity is required for high catalytic activity in higher alcohol synthesis.

Three-dimensional mesoporous sandwich-like g-C3N4-interconnected CuCo2O4 nanowires arrays as ultrastable anode for fast lithium storage

Inspite of their impressive high theoretical capacity as Lithium-ion batteries (LIBs) anodes, spinel transition-metal oxides (TMOs) suffer serious volume expansion, aggregation and the pulverization of crystal structures during lithiation/delithiation, and this process severely restrict their industrial application. Multi-dimensional morphological engineering of spinel TMO nanostructures is an effective way to solve this issue. In this work, using facile hydrothermal synthetic methods, spinel CuCo2O4 nanowires arrays are synthesized and supported on g-C3N4 nanosheets, thus forming a unique sandwich-like interconnected three-dimensional mesoporous structure containing high amount of void spaces. Addition of g-C3N4 nanosheets to CuCo2O4 nanowire arrays may shorten the Li+ diffusion distance and electron transfer pathway, and may also provide more active sites for Li+ diffusion into electrolyte and buffer for the volume expansion and aggregation of CuCo2O4. As a LIB anode material, CuCo2O4@g-C3N4 shows initial lithiation capacity of 840.6 mAh g−1, and capacity retention of 641.2 mAh g−1 after 60 cycles at the current density of 0.1 A g−1 and 499.2 mAh g−1 after 40 cycles at high current of 1 A g−1, which is significantly better than value of pure CuCo2O4 nanowires. This work affords a new way to tackle the problem of volume expansion of high capacity spinel TMO anode materials using g-C3N4 nanosheets as buffering agent.

The excellent catalytic activity for thermal decomposition of ammonium perchlorate using porous CuCo2O4 synthesized by template-free solution combustion method

Spinel CuCo2O4 with 3D macro-/mesoporous structure has been successfully synthesized via template-free solution combustion method. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and N2 absorption/desorption have been done to obtain compositional and morphological information as well as BET surface area of the as-synthesized sample. Catalytic activities of the porous CuCo2O4 towards the thermal decomposition of ammonium perchlorate (AP) were investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques. The results show that the addition of spinel CuCo2O4 with 3D macro-/nanoporousstructure to AP remarkably decreases the high temperature decomposition (HTD) from 470.92 °C for pure AP to 308.74 °C for AP containing CuCo2O4 additive with a mass ratio of 2%. The as-synthesized 3D macro-/nanoporous spinel CuCo2O4 is the promising type of catalytic materials for AP-based composite solid rocket propellants. The simple synthesis method is conducive to large-scale industrial production for application in AP thermal decomposition.

Hydrothermal induced novel CuCo2O4 electrode for high performance supercapacitor applications

A facile hydrothermal method has been used to synthesis of cubic CuCo2O4 nanoparticles by using two types of precipitate agents like oxalic acid and NaOH. XRD and TEM results suggest that spinel cubic structure of CuCo2O4 with space group of Fd3m. The N2 adsorption-desorption results confirms that oxalic acid assisted CuCo2O4 sample shows high surface area (133 m2g-1) and lower pore size 8–10 nm compared with NaOH assisted CuCo2O4 sample (surface area = 110 m2g-1 and pore size = 10–15 nm). The valance state of the sample was analyzed through XPS and the result suggests that the presence of mixed Co2+ and Co3+ in the CuCo2O4 spinel cubic system. Impressively, the electrochemical performance of the oxalic acid assisted CuCo2O4 electrode exhibits a maximum capacity of 765 mAhg−1 at a specific current of 2 A/g and results in good long term cyclic stability of 95% capacitance retention after 2000 cycles. Moreover, it delivers a high energy density of 25 W h/kg at a power density of 450 W/kg. This could be due to more electroactive sites for faradic reactions emerging from the two metal ions, higher electronic/ionic conductivity and fast electrolyte transportation kinetics promoted by unique morphology.

High-temperature stable refractory nanoneedles with over 99% solar absorptance

Solar absorber coatings have widely been investigated for solar-thermal technologies including concentrated solar power and solar thermochemistry. While various nanostructures such as nanowires and nanotubes have been commonly used for high solar absorptance owing to their potent light trapping effect, the high temperature stability of these nanostructures has yet to be established due to either coarsening of nanostructures or oxidation of certain materials in air (e.g., Si and C). In this work, we developed a nanostructured solar absorber from a family of high-temperature refractory spinel oxides, Co3O4 and CuCo2O4, with ultra-high solar absorptance over 99%. Once coated with a thin layer of HfO2 or SiO2 through atomic layer deposition, the Co3O4 and CuCo2O4 nanoneedles preserve their high aspect ratio and sharp tips, allowing the solar absorbers to maintain the superior absorptivity and excellent thermal stability at an elevated temperature for an extended period (650 °C and 800 °C for 100 h for passivated Co3O4 and Cu1Co2O4, respectively). These results suggest that solar absorbers made from refractory spinel oxide nanoneedles can be used for high-temperature solar thermal applications with ultrahigh absorptance.

Sustainable fixation of CO2 into epoxides to form cyclic carbonates using hollow marigold CuCo2O4 spinel microspheres as a robust catalyst

The present work demonstrates the chemical fixation of CO2 for the synthesis of organic carbonates using mesoporous hollow marigold CuCo2O4 spinel microspheres as a catalyst prepared using the solvothermal method.

CuCo Bimetallic Oxide Quantum Dot Decorated Nitrogen‐Doped Carbon Nanotubes: A High‐Efficiency Bifunctional Oxygen Electrode for Zn–Air Batteries

The large‐scale production of metal–air batteries, an appealing solution for next‐generation energy storage, requires low‐cost, earth‐abundant, and efficient oxygen electrode materials, yet insights into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen‐doped carbon nanotubes decorated by spinel CuCo2O4 quantum dots (CuCo2O4/N‐CNTs) is reported, outperforming the benchmark of state‐of‐the‐art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo2O4 and N‐doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu2+ and CuN) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo2O4/N‐CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all‐solid‐state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm−2 in liquid state, 1.86 W g−1 in all‐solid‐state), and long lifetime (48 h in liquid state, 9 h in all‐solid‐state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.