Cu-Co Catalysts Research Articles

Unveiling the synergistic mechanism of Co-Cu catalysts for efficient oxygen evolution reactions

The development of highly active electrocatalysts for Oxygen Evolution Reactions (OER) is critical in the field of energy conversion and storage. Among potential candidates, diatomic catalysts have demonstrated the potential to outperform monoatomic counterparts, though comprehensive studies on their reaction mechanisms remain limited. In this study, a Co-Cu diatomic catalyst was computationally designed using density functional theory (DFT), and four reaction pathways involving multiple intermediates (*O, *OH, *OOH, *2OH, *O + *OH) were calculated. The results indicate that the Co-Cu diatomic catalyst exhibits superior catalytic performance on pathway II (H2O → *OH → *2OH → *OOH → O2) with an overpotential of 0.27 V, overcoming the limitations imposed by the active site of conventional anion exchange membrane (AEM) catalysts. The high catalytic activity is attributed to the synergistic interaction between the metal atoms, bypassing the high-energy barrier step typically observed in conventional pathways. In this mechanism, the Cu d-band center is close to the Fermi energy level, enhancing electron transfer, while Co provides a stable adsorption site and effectively regulates the adsorption and conversion of reaction intermediates. These findings offer new strategies for the rational synthesis of bimetallic catalysts.

Active Sites on the CuCo Catalyst in Higher Alcohol Synthesis from Syngas: A Review

Higher alcohol synthesis through the Fischer–Tropsch (F–T) process was considered a promising route for the efficient utilization of fossil resources could be achieved. The CuCo catalysts were proven to be efficient candidates and attracted much interest. Great efforts have been made to investigate the active sites and mechanisms of CuCo catalysts. However, the industrialized application of CuCo catalysts in this process was still hindered. The poor stability of this catalyst was one of the main reasons. This short review summarized the recent development of active sites on the CuCo catalysts for higher alcohol synthesis, including CuCo alloy particles, CuCo core–shell particles, and unsaturated particles. The complex active sites and their continual changes during the reaction led to the poor stability of the catalysts. The effect of active sites on catalytic performance was discussed. Furthermore, the key factors in fabricating stable CuCo catalysts were proposed. Finally, reasonable proposals were proposed for designing efficient and stable CuCo catalysts in higher alcohol synthesis.

Cu-Co Bimetallic Catalyst-based Electrochemical Sensing Platform for Determination of Bisoprolol in Clinical Samples.

Bisoprolol (BIS) is a selective beta-blocker. It has been successfully used to treat hypertension and angina pectoris. An overdose of BIS can lead to serious complications. An overdose is a medical emergency that requires immediate medical attention to overcome the adverse effects of the overdose. Hence, sensitive, reliable, and cost-effective methods are required for the determination of BIS. In this work, a new electrochemical sensing platform based on a bimetallic catalyst was developed for the determination of BIS. The Cu-Co nanocatalyst was easily synthesized by galvanic displacement onto a carbon paste electrode (CPE). Then, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and cyclic voltammetry (CV) were utilized for the characterization of the Cu-Co catalyst. The galvanic displacement of Cu metal significantly affected the electro-catalytic behavior of the Cu-Co catalyst and the Cu-Co/CPE electrode displayed a very sensitive and accurate response towards BIS. Under optimized conditions, the response was linear in the 3 to 120 μM concentration range, sensitivity of 631.1 μA mM-1 and a detection limit of as low as 0.4 μM using cyclic voltammetry. The simple proposed method was also successfully employed in the analysis of BIS in biological and pharmaceutical samples. The advantages of Cu-Co/CPE are its fast and simple manufacturing and the possibility of a repeated surface regeneration of the sensing platform, as well as its application for the detection of BIS in tablets and biological samples, making Cu-Co significant promise for use in clinical diagnostics. Besides, the synthesized catalysts showed excellent reusability and stability. The presence of Cu metal due to galvanic displacement increased the sensitivity. These findings suggest that the new nanocatalyst has potential applications in sensors and electronics.

Bimetal (CuNi and CuCo) substituted CeO2: An approach for low temperature dry reforming of methane

The solution combustion synthesis method was used to make CuNi substituted CeO2 (7.5 at.% of Cu+7.5 at.% of Ni), and CuCo substituted CeO2 (7.5 at.% of Cu+7.5 at.% of Co) catalysts. The catalysts were characterized by x-ray diffraction (XRD),XPS, BET surface area measurements, scanning electron microscopy (SEM), and H2-temperature-programmed reduction(H2-TPR). Further, these catalysts were tested for endothermic dry reforming of methane (DRM) reaction. The CuNi substituted CeO2 catalyst started dry reforming of methane (DRM) at around 350 °C, while the CuCo substituted CeO2 catalyst started DRM at around 450 °C. This indicates that the CuNi catalyst has a lower activation temperature for the DRM reaction compared to the CuCo catalyst. The CuNi substituted CeO2 catalyst converted CH4 better than the CuCo substituted CeO2 at all temperatures reaching 98 % conversion at 800 °C The CuNi substituted CeO2 showed higher H2/CO ratio in comparison to the CuCo substituted CeO2 but the long-term stability followed the opposite order. Thermal gravimetric analysis (TGA), SEM and O2-TPO were used to quantify as well as to understand the nature of carbon that had built up on spent catalysts and it is mostly amorphous. Transient studies have shown that along with the lattice oxygen participation, controlled methane decomposition step is necessary for stability of catalysts. Transient studies also recommended additional reaction steps during DRM where an exothermic methane partial oxidation step reduces the endothermicity of DRM. Also, CO2 activation also goes via the defect dissociation route, an additional step to the conventional carbon oxidation (CO2+C→CO) step. So, novelty of this work is in elucidating the exact role of lattice oxygen in imparting the activity and stability to the DRM catalyst.

Enhanced bimetallic CuCo nanoparticles on nitrogen-doped carbon for selective hydrogenation of furfural to furfuryl alcohol through strong electronic interactions

Bimetallic CuCo catalysts with different Cu to Co ratios on N-doped porous carbon materials (N-C) were achieved using impregnation method and applied in the hydrogenation of furfural (FAL) to furfuryl alcohol (FOL). The high hydrogenation activity of FAL over Cu1Co1/N-C was originated from the synergistic interactions of Cu and Co species, where Co0 and Cu0 simultaneously adsorb and activate H2, and Cu+ served as Lewis acid sites to activate C═O. Meanwhile, electrons transfer from Cu to Co promoted the formation of Cu+. In situ Fourier transform infrared spectroscopy analysis indicated that Cu1Co1/N-C adsorbed FAL with a tilted η1-(O) configuration. The superior Cu1Co1/N-C showed excellent adsorbed ability towards H2 and FAL, but weak adsorption for FOL. Therefore, Cu1Co1/N-C possessed 93.1% FAL conversion and 99.0% FOL selectivity after 5 h reaction, which also exhibited satisfactory reusability in FAL hydrogenation for five cycles.

Potassium-mediated control of adsorbed intermediates on CuCoAl layered nanoplates for ethanol synthesis from syngas

A set of K-promoted CuCoAl nanoplates were synthesized via precipitation followed by impregnation method and assessed for syngas conversion. The optimized 1K-CuCo catalyst manifested a relatively higher total alcohols selectivity of 48.4 %, with ethanol comprising 35.4 % of total alcohols. As indicated by in situ CO DRIFT and XPS outcomes, on the 1K-CuCo catalyst surface, a distinct preference was observed for the adsorption of CO on Cu+ species (non-dissociative CO*) and bridging CO adsorption on Co species (dissociative CO*). A substantial presence of strongly adsorbed formate species, which contributed favorably to the production of CHx* intermediates, was also identified on the optimal catalyst surface. More importantly, operando DRIFT characterization confirmed that K-modified CuCo catalyst effectively inhibited the hydrogenation (or coupling) of adsorbed CHx* intermediates derived from formate species to generate methane and C2+H. Instead, the adsorbed CHx* intermediates coupled with non-dissociated CO* to form CHxCO* species. Therefore, the K promoter can finely regulate the adsorption strength and distribution of intermediates species, thus furnishing sufficient CHx* intermediates and CO* species to take part in CHx-CO coupling reaction to synthesize ethanol.

CNTs-promoted Co-Cu Catalyst for Efficient Synthesis of Cinnamyl Alcohol from Hydrogenation of Cinnamaldehyde

CNTs-promoted Co-Cu Catalyst for Efficient Synthesis of Cinnamyl Alcohol from Hydrogenation of Cinnamaldehyde

Double core–shell hollow nanocage CuO@Co3O4 for the selective hydrogenolysis of C–O bonds of lignin without external hydrogen

The design of a highly active Cu-Co catalyst for catalytic transfer hydrogenolysis of lignin without the use of external hydrogen remains highly challenging. In this work, Cu2O was initially encapsulated in ZIF-67, and subsequently Cu2O@ZIF-67 was utilized as a precursor and sacrificial template to prepare the unique double core–shell hollow nanocage CuO@Co3O4. Co and Cu, serving as Lewis acid sites and dehydrogenation sites for the hydrogen-donor solvent isopropanol, respectively, exhibited synergistic enhancement, further increasing the catalytic activity. Under the optimal conditions of 220 °C, 1 MPa N2, and 4 h, the catalyst achieved 100 % conversion of 2-phenoxy-1-phenylethanol and 100 % yield towards cyclohexanol and ethylbenzene. Furthermore, the catalyst remained stable and reusable after 5 cycles, providing a practicable guidance for the value-added conversion of lignin.

Space confinement effect of carbon nanotube-alumina strip support on the Cu-Co catalysts for CO2 methanation

The present work reported the space confinement effect of carbon nanotube-alumina strip (CAS) support on the Cu-Co bimetallic catalyst or the single Cu, Co catalysts for the CO2 methanation. CAS, made by extrusion of nanotubes and Al-based sol and high temperature calcination, was a macroscopic support with sufficient mesopores and hydrophobic property. Cu-Co/CAS catalysts exhibited high catalytic activity for methanation of CO2 (H2/CO2=3:1), where CO2 conversion was 49.62% and CH4 selectivity was 95.98% at temperature as low as 250 ℃ and 1.5 MPa, and showed advantage significantly over those with the supports of individual nanotube or pure Alumina support. The comparison suggested the hydrophobicity of carbon nanotubes can effectively remove water from the metal active sites, enhancing the equilibrium of reverse water gas shift and CO methanation reactions, as compared to alumina support. Additionally, CAS support had a spatial confinement effect that increased the contact time of CO2 or intermediates with the active sites, compared with individual nanotube support. XPS and Raman spectroscopy validated the presence of oxygen vacancies of CAS, promoting the CO2 methanation. H2-TPR results, in combination with DFT calculations, confirmed that the CAS supports enabled the Cu-Co active phase by changing their electronic structures, to possess a strong adsorption activation capacity for H2 at low temperatures with high performance for CO2 methanation.

Boron-doped Cu-Co catalyst boosting charge transfer in photothermal carbon dioxide hydrogenation

Photothermal catalysis of CO2 hydrogenation holds great potential in achieving carbon neutrality. However, the rational design of cost-effective photothermal catalysts with high performance for CO2 hydrogenation is an ongoing challenge. Herein, we employed CuCoyBOₓ composite catalysts by incorporating both CuBOₓ and amorphous CoBOₓ to efficiently catalyze the CO2 hydrogenation. Besides the high selectivity (98.0%), the optimized CuCo5BOx demonstrated a remarkable CO yield of 124.7 mmol g⁻¹ h⁻¹ under illumination at 300°C, which was 3 times higher than the traditional thermocatalysis. Experimental results and theoretical calculations demonstrated CuBOₓ acted as a photocatalyst, donating electrons to CoBOₓ active sites. Coupling boron-oxygen species with CuCo bimetallic-oxides synergically enhanced the CO2 adsorption capacity and accelerated charge transfer, thereby enhancing the photothermal synergistic effect and consequently boosting the catalytic activity. This study establishes an approach for the rational design of non-precious metal-boride catalysts, enabling efficient photothermal conversion of CO2 into CO under mild conditions.

Highly active CeO2-CuCo nanoparticles supported on hollow N-doped carbon spheres for boosting ammonia borane hydrolysis and tandem 4-nitrophenol reduction reactions

It’s a safe method to use high hydrogen density ammonia borane (AB) to facilitate the tandem hydrogenation of aromatic nitro compounds. While a major problem for tandem hydrogenation, the development of non-noble metal catalysts with high activity and stability is encouraging. This work involved the synthesis of highly active CeO2/CuCo nanoparticles support on hollow N-doped carbon spheres and its investigation for AB hydrolysis, taking into account the impacts of the HNCSs and CeO2 supports. Because CuCo alloy, CeO2, and HNCSs supports worked in concert, HNCSs@CeO2/CuCo was found to be the best catalyst. The activation energy achieved was comparable to the reported Pd- and Pt-based catalysts, with a value as low as 21.8 kJ/mol. Using AB as the in-situ H2 source, HNCSs@CeO2/CuCo exhibited a significant degree of activity in the one-pot tandem reduction of 4-NP with the turnover frequency of 2830.2 h−1, even surpassing over ten times of some noble metal catalysts. Following five consecutive cycles of reaction condition tuning, the HNCSs@CeO2/CuCo catalyst demonstrated a constant conversion efficiency. Also, the catalyst's uses for one-pot tandem reduction of other highly active aromatic nitro compounds were expanded.

Co(II)-Cu(II) mixed-oxide catalysts for single-step synthesis of 2,4,5-triaryl-1H-imidazole derivatives under microwave irradiation.

In this study, a catalyst composite of Co-Cu was prepared from chloride-containing precursor of Co(II) and Cu(II) metals using the milky latex of the Euphorbia neriifolia plant following green principles of synthesis. The catalyst composite was characterized using XRD, EDAX, SEM, HR-TEM, FTIR, XPS and TOF-MS. The crystallinity of the mixed-oxide composite with a distorted octahedral nature was confirmed from analysis. Chemical charge analysis of the Co-Cu mixed phase based on XPS revealed Co2+ and Cu2+ oxidation states. This material was used for synthesizing 2,4,5-triaryl-1H-imidazole (TIMDZOL) derivatives. Analysis of reaction conditions revealed that EtOH : PEG at 8 : 2 ratio under microwave conditions showed better yields with less time and better reusability of the Co-Cu catalyst.

Enhancing the oxygen evolution reaction activity of CuCo based hydroxides with V2CT x MXene.

The oxygen evolution reaction (OER) is a key reaction in the production of green hydrogen by water electrolysis. In alkaline media, the current state of the art catalysts used for the OER are based on non-noble metal oxides. However, despite their huge potential as OER catalysts, these materials exhibit various disadvantages including lack of stability and conductivity that hinder the wide-spread utilization of these materials in alkaline electrolyzer devices. This study highlights the innovative chemical functionalization of a mixed copper cobalt hydroxide with the V2CT x MXene to enhance the OER efficiency, addressing the need for effective electrocatalytic interfaces for sustainable hydrogen production. The herein synthesized CuCo@V2CT x electrocatalysts demonstrate remarkable activity, outperforming the pure CuCo catalysts for the OER and moreover show increased efficiency after 12 hours of continuous operation. This strategic integration improved the water oxidation performance of the pure oxide material by improving the composite's hydrophilicity, charge transfer properties and ability to hinder Cu leaching. The materials were characterized using an array of materials characterization techniques to help decipher both structure of the composite materials after synthesis and to elucidate the reasoning for the OER enhancement for the composites. This work demonstrates the significant potential of TMO-based nanomaterials combined with V2CT x for advanced innovative electrocatalytic interfaces in energy conversion applications.

Enhanced performance of heterogeneous fenton-like Co-Cu catalysts for metronidazole degradation: Ethylene glycol as a superior fabrication solvent

This study addresses the gap in understanding of fabrication solvent influence on Cu-Co catalyst performance for MNZ degradation. By synthesizing recyclable Cu-Co catalysts using the co-precipitation method, the study investigates the impact of ethylene glycol (EG) solvent compared to conventional water (H2O) solvent. The optimized operational parameters resulted in stable and high MNZ degradation efficiency (above 90 % removal) with twice-feeding of 1600 ppm H2O2, pH ∼7.15, and 50 °C. The use of EG solvent enhances catalyst surface area, exposing more active sites with higher Cu+ and Cu2+ content, which incorporated in CoO6 environment with promoted redox property to facilitate H2O2 reaction and •OH production. This research contributes valuable insights into catalyst design and optimization, highlighting the potential of EG solvent for industrial application in antibiotic organic pollutant remediation.

Cold plasma-activated Cu-Co catalysts with CN vacancies for enhancing CO2 electroreduction to low-carbon alcohol

Electrocatalytic CO2 reduction reaction to low-carbon alcohol is a challenging task, especially high selectivity for ethanol, which is mainly limited by the regulation of reaction intermediates and subsequent C–C coupling. A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H2 cold plasma toward a high-efficiency CO2RR into low-carbon alcohol. The Cu-Co PBA-VCN (Prussian blue analogues with CN vacancies) electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8% (methanol: 39.2%, ethanol: 44.6%) at −0.9 V vs. RHE, excellent durability (100 h) and a small onset potential of −0.21 V. ATR-SEIRAS (attenuated total internal reflection surface enhanced infrared absorption spectroscopy) and DFT (density functional theory) reveal that the steric hindrance of VCN can enhance the CO generation from *COOH, and the C–C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms. This work provides a strategy for the design and preparation of electrocatalysts for CO2RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.

Theoretical insights on the effect of alloying with Co in the mechanism of graphene growth on a Cu[sbnd]Co (1 1 1) catalyst

Alloying Cu catalyst with transition metals with high C solubility is an effective technique for growing graphene with a precisely controlled number of layers. Co is a transition metal with high C solubility and is suitable for alloying with Cu catalysts due to its similar atomic size. In this study, we elucidate the mechanism of graphene growth on a CuCo(111) catalyst by evaluating the energetics, thermodynamics, and kinetics of potential C source species, CHi (i = 0, 1, 2, 3), using a first-principles method. Alloying Cu with Co atoms upshifts the d-band center, which induces a robust p-d hybridization between the CuCo(111) catalyst and the C source species. From relative population calculations, it is found that the C monomer on the catalyst subsurface always becomes dominant in the range of growth conditions studied. Therefore, the C monomer in the catalyst subsurface controls the segregation growth mechanism. In addition, it is found that the diffusion of C monomer into the CuCo(111) catalyst subsurface is an exothermic process with a low activation energy. These results enable us to suggest a novel alternating alloy catalyst for growing few-layer graphene with a precisely controlled number of layers.

Fabrication of multiatomic structure of Cu-CoO/Co interface for efficient hydrogen generation from ammonia borane hydrolysis

Hydrogen generation from hydrolysis of ammonia borane is a secure and promising route for conversion of hydrogen energy. Preparation of efficient and economical catalysts is highly required for the development hydrogen economy. In this study, the Co-based catalysts with multiatomic structure were designed for hydrolysis of ammonia borane reaction. The synergistic effect between Co and M (M = Cu, Ni, Fe) greatly enhanced the catalytic performance of bimetallic catalysts. The TOF value of CoCu-NC-5 towards 8.12 min−1 is 7 times that of the single Co catalyst. Moreover, The CoCu catalysts showed the stronger synergistic effect and highest catalytic activity for hydrogen generation, compared with CoNi and CoFe catalysts. The TOF value of CoCu-NC-5 is 2.3 and 6.0 times that of CoFe-NC-5 and CoNi-NC-5 catalysts, respectively. The active component structure of Cu-CoO/Co interface in CoCu-NC-5 is beneficial for activation and dissociation of water molecule due to the strong electron transfer effect and positive synergy. The activation energy over CoCu-NC-5 is 34.25 kJ mol−1, and the catalyst exhibited good stability. This work provides a feasible method for rational design of efficient catalysts with hierarchical structure for conversion of energy.

Hydrolysis of Ammonia Borane for Hydrogen Generation on Bimetallic CoCu Catalysts: Regulation of Synergistic Effect

Hydrolysis of Ammonia Borane for Hydrogen Generation on Bimetallic CoCu Catalysts: Regulation of Synergistic Effect

Cobalt-Copper Oxide Catalysts for VOC Abatement: Effect of Co:Cu Ratio on Performance in Ethanol Oxidation

The effect of the Co-Cu oxide catalysts composition on their physicochemical properties and performance in the deep oxidation of ethanol was studied. The catalysts with Co:Cu molar ratios of 4:1, 1:1, and 1:4 were obtained by calcination (4 h at 500 °C in air) of the coprecipitated precursors and characterized in detail using powder XRD, Raman spectroscopy, N2 physisorption, H2-TPR, and XPS. The powder XRD and Raman spectroscopy indicated the formation of Co3O4 and CuO mixtures rather than Co-Cu mixed oxides. The CuO promoted the Co3O4 reduction; the Co-Cu catalysts were reduced more easily than the single-component Co and Cu oxides and the main reduction maxima were shifted to lower temperatures with increasing cobalt content in the catalysts. The Co-Cu oxide catalyst with a Co:Cu molar ratio of 4:1 exhibited the best performance in ethanol gas-phase oxidation, showing the lowest T50 (91 °C) and T90(CO2) (159 °C) temperatures needed for 50% ethanol conversion and 90% conversion to CO2, respectively. The excellent catalytic properties of this Co-Cu oxide catalyst were ascribed to the synergistic effect of Co and Cu components. The high activity and selectivity of the Co-Cu catalyst was attributed to the presence of finely dispersed CuO particles on the surface of Co3O4.

Rational design of hydroxyapatite/graphite-supported bimetallic Cu–M (M = Cu, Fe, Co, Ni) catalysts for enhancing the partial hydrogenation of dimethyl oxalate to methyl glycolate

Noble metal-free hydroxyapatite (Ca10(PO4)6(OH)2)/graphite composite supported CuCo catalysts are developed and exhibited outstanding stability and catalytic performance in dimethyl oxalate hydrogenation reaction to methyl glycolate.