Copper Cobalt Research Articles

Hierarchical flower-like nanostructures of manganese–cobalt–copper nanoneedles for high performance symmetric supercapacitor

Hierarchical flower-like structures of nanoneedles of ternary metal oxides comprising of Manganese–Cobalt–Copper (MCC) are synthesized on nickel foam by a simple hydrothermal technique. The synthesis of MCC is done with varying concentrations of manganese and copper, and the products are studied using X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. Electrochemical studies of MCC electrodes are performed using cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance spectroscopy. Ternary metal oxide electrode demonstrates better electrochemical performance in comparison to mono and bimetallic oxide electrodes, which can be attributed to synergistic effects between the metals. Specific capacitance of 1607 F/g at scan rate 5 mV/s is shown by the best performing MCC electrode. The capacitance retention is 98.33% after 2800 charge-discharge cycles. Symmetric device fabricated by the MCC electrode delivers energy density of 37 W h/kg at a power density of 228 W/kg.

Amorphous copper cobalt carbonate hydroxide prepared by SILAR on copper foam for non-enzymatic glucose sensing

Amorphous copper cobalt carbonate hydroxide prepared by SILAR on copper foam for non-enzymatic glucose sensing

MoS2 mediated tuning of CuCo2S4–MoS2 nanocomposites for high-performance symmetric hybrid supercapacitors

CuCo2S4–MoS2 nanocomposites were synthesized by optimizing the concentration of MoS2 to enhance electrochemical performance, including storage capacity, energy density, and stability for use as efficient electrode materials in hybrid supercapacitors.

Selective tandem electroreduction of nitrate to nitrogen via copper–cobalt based bimetallic hollow nanobox catalysts

The hollow Cu–Co HNB catalyst selectively reduces NO3− to N2 by tandem catalysis in a chlorine-free system.

Catalytic performance of nano-sized cobalt copper ferrite on thermal decomposition of ammonium nitrate

Ammonium nitrate (AN) is being explored as a high energetic oxidizer in propellants. The utilization of pure AN in propellants suffers from a low burning rate. To improve the burning rate, it is important to improve the thermal decomposition characteristics of AN to fasten its thermal decomposition. The effect of CoCuFe2O4 additive was explored to improve the thermos-kinetic parameters of AN's thermal decomposition. Coprecipitation was used to synthesize nanocrystalline CoCuFe2O4. The thermodynamic and kinetic parameters of decomposition of AN: CoCuFe2O4 were investigated using TG-DSC-DTA analysis at 5, 10, and 15 °C min−1. The thermodynamic and kinetic studies suggest that the thermal decomposition of AN+CoCuFe2O4 was more favorable than AN. The decomposition of AN+CoCuFe2O4 occurs at a lower 10 °C lower temperature with ∼44 % decrement in the activation energy and decreased pre-exponential factor. The faster decomposition at a lower temperature was obtained for AN+CoCuFe2O4 composition. Nano-sized particles with efficient optical and polarizable properties made this ferrite material easily separable and eco-friendly for the preparation of a chemical propulsion system based on AN. The AN+CoCuFe2O4 propulsion mixture can be utilized in place of pure AN for better thermal performance in a propellant system.•CoCuFe2O4 was able to influence the thermal decomposition parameters of ammonium nitrate (AN).•AN+CoCuFe2O4 decomposes at lower activation energy with a faster decomposition than pure AN.•Thermodynamics suggest favorable decomposition of AN+CoCuFe2O4 than pure AN.

An Efficient Nanocatalyst Cobalt Copper Zinc Ferrite for the Thermolysis of Ammonium Nitrate.

This work reports synthesis and catalytic effect of cobalt copper zinc ferrite (CoCuZnFe2O4) on the thermal decomposition of ammonium nitrate (AN). AN is a crystalline hygroscopic powder widely applicable as an oxidizer in the propellant formulations for high energetic materials but requires improvement in its thermal decomposition characteristics. Nanocatalyst spinel ferrite CoCuZnFe2O4 was prepared using the coprecipitation method and characterized by various physicochemical instrumental techniques like XRD, FE-SEM, UV-vis, Raman, and TG-DSC. Catalytic study of AN in the presence of nano-CoCuZnFe2O4 was investigated using DSC analysis. The Raman and XRD study confirm the formation of ferrite with a crystalline size 9-22 nm. TG suggests that the catalyst was thermally stable up to 400 °C with ∼10% mass loss. The UV-vis study shows that the optical band gap energy of CoCuZnFe2O4 was 2.6 eV, which may help in fast acceleration of electrons during thermolysis of AN, making the thermal decomposition of AN more favorable in the presence of CoCuZnFe2O4. The thermal decomposition investigation suggests that the activation energy of AN thermolysis in the presence of 2 wt % CoCuZnFe2O4 was decreased by ∼37%. It is concluded that CoCuZnFe2O4 can be used as an efficient catalyst for improving AN's thermal characteristics.

A new strategy for selective recovery of low concentration cobalt ions from wastewater: Based on selective chelating precipitation-flotation process

BackgroundA significant amount of low-concentration heavy metal ion wastewater is generated daily by the mining and metallurgy industry, endangering human health and the environment. A novel method of selective chelating precipitation–floatation of copper and cobalt ions is proposed for the recovery of cobalt from wastewater. MethodsBased on the chelation of cobalt and copper ions with α-nitroso-β-naphthol (NN), the flotation process is adopted to solve the problem of fine particle separation from solution in low-concentration ions removal. Significant findingsUnder the optimized precipitation flotation conditions, the flotation recovery ratios of the copper, cobalt, and zinc ions were found to be 98.47%, 42.48%, and 9.35%, respectively, and the separation effect of cobalt and zinc showed to be outstanding, as their separation factor reached 598. Industrial wastewater also has a good flotation separation effect. Based on the mechanism studies, Co2+/Co3+ and Cu2+ were selectively chelated by NN to form hydrophobic NN-Co/Cu precipitation particles. Moreover, electrostatic attraction is the main force in the proposed flotation process. Eventually, we tried calcination to recycle the flotation products to verify the potential of the cobalt–copper composite oxides in capacitor materials. The results prove that the precipitation–flotation method has great efficiency and potential for selectively recovering low-concentration metal ions and separating fine particles from solution.

Tunable Fabrication of Hollow Nano Sword-Like CuCo2O4 Derived from Bimetal–Organic Frameworks as Binder-Free Electrodes

This study successfully synthesized highly porous hollow nano sword-like CuCo2O4 with a large specific surface area (80.2 m2 g–1) on a nickel foam substrate through a simple solution-based method followed by a calcination process. Benefiting from their geometrical merits, including excellent structural robustness, large electroactive surface areas, and 3D open structures, the hollow nano sword arrays of CuCo2O4 deliver remarkable electrochemical performances for SCs. Using this binder-free strategy, the synthesized copper cobalt oxide electrode delivers a great specific capacity of 717 C g–1 at 1 A g–1 with an excellent rate capability and cycling stability in a three-electrode cell configuration. Consequently, the fabricated CCO-HS//AC device exhibits the highest specific energy of 54 Wh kg–1 at a specific power of 3137 W kg–1 with a remarkable cycle stability of 91.1% capacity retention after 8000 cycles, indicating its potential as a novel electrode for energy storage systems.

Electrocatalytic oxygen reduction activity of AgCoCu oxides on reduced graphene oxide in alkaline media.

Silver-based electrocatalysts as promising substitutes for platinum materials for cathodic oxygen electroreduction have been extensively researched. Electrocatalytic enhancement of the Ag nanoarchitectonics can be obtained via support structures and amalgamating Ag with one or two additional metals. The work presented here deals with a facile microwave-assisted synthesis to produce bimetallic Ag-Cu and Ag-Co (1:1) oxide nanoparticles (NPs) and trimetallic AgCuCo (0.6:1.5:1.5, 2:1:1, and 6:1:1) oxide NPs supported on a reduced graphene oxide (rGO) matrix. Morphology, composition, and functional groups were methodically analysed using various microscopic and spectroscopic techniques. The as-prepared electrocatalysts were employed as cathode substrates for the oxygen reduction reaction (ORR) in alkaline medium. Varying the Ag fraction in copper cobalt oxide has a significant influence on the ORR activity. At a ratio of 2:1:1, AgCuCo oxide NPs on rGO displayed the best values for onset potential, half-wave potential, and limiting current density (Jk) of 0.94 V vs RHE, 0.78 V, and 3.6 mA·cm−2, respectively, with an electrochemical active surface area of 66.92 m2·g−1 and a mass activity of 40.55 mA·mg−1. The optimum electrocatalyst shows considerable electrochemical stability over 10,000 cycles in 0.1 M KOH solution.

Copper-Cobalt-Based Sulfides: Strategy To Boost Energy Storage Performance Utilizing the Synergistic Effect of a Double Metal Ion

The copper cobaltite chalcogenides were designed and developed via a simple and economically effective electrochemical route followed by the hydrothermal anion-exchange process without altering the morphological features. The systematic synthetic approach provided spinel crystalline-structured copper cobalt sulfide (CuCo2S4) through in situ co-deposition and copper sulfide/cobalt sulfide composite (CuS/CoS) via layer-by-layer deposition. Obtained high-resolution scanning electron microscopy explains the unique dendrite morphology of copper cobalt sulfide (CuCo2S4) with a primary midrib followed by secondary and tertiary trunks, whereas CuS/CoS governs a distinct CuS dendrite covered with thin CoS sheets homogeneously. Furthermore, the CuCo2S4 electrode material governed a superior charge storage property in supercapacitor application with a capacitive value of 966–676.8 C g–1 at a current density ranging from 10 to 40 A g–1 with a 70.15% retention value, whereas CuS/CoS delivered only 455.3–278.8 C g–1 at current densities with 61.23% retention. The promising faradaic behavior of the as-prepared material was attributed by the stable charge-discharge profile at different applied current densities as 10, 20, 30, 40, and 10 A g–1 for 5000 cycles for CuCo2S4 and CuS/CoS electrodes, respectively. To evaluate real-time charge storage behavior, an asymmetric device was assembled by coupling the CuCo2S4 electrode with activated carbon electrode using a 3 M KOH aqueous electrolyte. The fabricated device delivered 126.8 and 81.45 C g–1 at 10 and 50 A g–1, respectively. Moreover, the device demonstrated excellent cycling stability up to 5000 cycles at 50 A g–1 with 96.70% capacitive retention. Thus, the present work demonstrates the most effective strategy to exploit the synergistic effect of bimetal ions to boost the charge storage properties of a ternary chalcogenide electrode.

Structural, optical and electrical properties of Cu2CoSnS4 thin film solar cells prepared by facile sol-gel route

• Copper cobalt tin sulfide (Cu 2 CoSnS 4 ) thin films were deposited by sol-gel method. • Physical and chemical properties of Cu 2 CoSnS 4 thin film were investigated. • The Cu 2 CoSnS 4 –based solar cells with an efficiency of 4.83% were achieved. The copper cobalt tin sulfide Cu 2 CoSnS 4 (CCTS) thin films are among the most promising materials for power conversion. We carried out a study on copper-cobalt tin sulfide thin films deposited via a simple route using the sol-gel spin-coating method. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive analysis, and Hall effect measurements were performed to investigate the impact of the annealing temperature on structural, morphological, compositional, optical, and electrical properties of the CCTS thin films. The optimum annealing conditions for obtaining pure CCTS thin films, with good crystallinity, stoichiometry, and surface morphology were found to be 300 °C for 60 min in a nitrogen atmosphere. In addition, the films show a p-type conductivity with a sheet carrier concentration of 1.2 10 17 cm −3 , sheet resistivity of 0.18 Ω.cm, Hall mobility of 5.8 cm 2 /V.s, the optical band gap of 1.4 eV and an absorption coefficient more than 10 4 cm −1 . In addition, the CCTS-based solar cells were fabricated. Under simulated AM 1.5 illumination conditions, the solar cells showed a high open-circuit voltage of 0.79 V, a short-circuit current density of 17.5 mA/cm 2 , a fill factor of 35%, and the conversion efficiency of 4.83 %. These results indicate that the annealed CCTS thin films at 300 °C in nitrogen atmosphere without sulfurization process are promising for low-cost effective thin-film solar cells.

Highly dispersed face-centered cubic copper–cobalt alloys constructed by ultrafast carbothermal shock for efficient electrocatalytic nitrate-to-ammonia conversion

Ammonia is a promising new generation of green energy that has the potential to replace hydrogen energy and facilitate the energy structure optimization of human society. However, the technology of green ammonia production under ambient conditions is still immature. It is urgent to develop new strategies for efficient and green ammonia production adapted to distributed energy, resource environment, and human health. Hereon, a highly dispersed face-centered cubic copper–cobalt alloy was prepared by ultrafast carbothermal shock for green ammonia production from nitrate under ambient conditions. The Cu2.5Co alloy achieves a remarkable ammonia yield of 164.23 μmol/h/cm2 and an exceptional faradaic efficiency of 96.29% at −0.25 V and −0.05 V versus reversible hydrogen electrode in a neutral solution. The electronic regulation of Co on Cu reduces the Tafel slope from 182 mV/dec of monometallic Cu to 108 mV/dec of bimetal Cu2.5Co alloy; the addition of Co optimizes the overall catalytic activity of the catalyst. This work provides a new idea for the design and synthesis of high-efficiency electrocatalyst for green ammonia production from nitrate and water under ambient conditions.

Y3+ substituting-adjusted mechanical, dielectric, and impedance properties of cobalt copper zinc nanoferrites for high frequency applications

Upgrading mechanical-dielectric features of ferrites through rare-earth yttrium (Y3+) doping provides feasibility to evolving high-frequency electronic devices. This paper reports the mechanical and dielectric properties of Co0.5Cu0.25Zn0.25YxFe2–xO4 ferrite nanoparticles labeled as CCZYF#0, CCZYF#1, CCZYF#2, CCZYF#3, CCZYF#4 and CCZYF#5 for x = 0.0, 0.02, 0.04, 0.06, 0.08, and 0.1, respectively. The frequency and temperature dependence of dielectric parameters and conductivity of all CCZYF nanoferrites are well discussed. The nanoferrite CCZYF#5 has the highest dielectric constant (enhancing ratio 170%) and the highest conductivity (enhancing ratio 7125.81%) compared with the undoped sample. Nyquist plots of all CCZYF nanoferrites manifest two arcs; the main reasons for the dielectric process are the grain boundaries and bulk grains. All impedance parameters were determined, which showed the effective role of Y3+ ions on their values. The nanoferrite CCZYF#5 has the highest grain boundaries capacitance (with enhancing ratio of 59.40%) and the highest grains capacitance (with enhancing ratio of 22.53%) with a relaxation time decrement efficiency of 62.51%. An ultrasonic flaw detector was utilized to determine the elastic moduli of all CCZYF nanoferrites. The nanoferrite CCZYF#5 has the highest longitudinal modulus (with enhancing ratio of 20.95%), the highest shear modulus (with enhancing ratio of 48.72%), highest Young's modulus (with enhancing ratio of 88.47%), the highest bulk modulus (with enhancing ratio 13.27%) and the highest micro hardness (with enhancing ratio 77.77%). Hence, Y3+ tuned Co-Cu-Zn nanoferrites possess new opportunities for high-frequency and storage applications.

Enhancing deep mineralization of refractory benzotriazole via carbon nanotubes-intercalated cobalt copper bimetallic oxide nanosheets activated peroxymonosulfate process: Mechanism, degradation pathway and toxicity

Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) are effective methods for the degradation of highly toxic and refractory nitrogen-containing heteroatomic pollutants such as benzotriazole (BTA). The construction of catalytic materials with multiple active centers is the key to generating abundant reactive oxygen species (ROS) and achieving high mineralization efficiency in PMS-AOPs. Herein, carbon nanotubes-intercalated cobalt copper bimetallic oxide nanosheets catalyst (CoCuNS@CNTs) was obtained by pyrolysis of two-dimensional (2D) MOF precursor. The degradation rate constant of BTA in CoCuNS@CNTs/PMS system was 4 times higher than that of metal oxide nanosheets catalyst without CNTs, while exhibiting high cycling stability and mineralization efficiency. Serial characterizations demonstrated that CoCu nanosheets was formed by CNTs-induced the directional assembly of metal oxide nanoparticles, which had high graphitization and abundant oxygen vacancies and could greatly facilitated the adsorption and electron transfer between the catalyst, PMS and BTA. Moreover, the doping of Cu species significantly improved PMS utilization and accelerated the Co(III)/Co(II) redox cycle. Both radicals (SO4–• and •OH) and non-radicals (1O2) played a role in CuCoNS@CNTs/PMS system and the contributions of ROS were 72.2%, 11.1% and 16.7%, respectively. Meanwhile, the concentration of key ROS (SO4–•) production increased from 4.76 μM to 8.56 μM compared with cobalt oxide nanosheets (CoNS). Three degradation pathways of BTA were proposed: benzene ring opening, benzene ring hydroxylation and triazole ring dimerization. Finally, the toxicity changes during the degradation process were measured and the toxicity of eleven intermediates was evaluated. This study may provide new insights into the degradation of persistent organic pollutants.

Combustion process for magnetic copper–cobalt ferrite and its Congo red adsorption property

A rapid combustion process was introduced for the preparation of magnetic copper–cobalt ferrite, which was characterized using X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Brunauer–Emmett–Teller techniques (BET). The prepared magnetic copper–cobalt ferrite showed a large specific surface area (104.6 cm2 g−1) and nanoscale particle size (55.4 nm), with a saturation magnetization of 19.6 Am2 kg−1. The nanoparticles were used to adsorb and remove Congo red (CR) from dyestuff wastewater, and the adsorption mechanism was revealed. Compared with the pseudo-first-order kinetic model and intraparticle diffusion kinetic model, the pseudo-second-order kinetic model was better at describing the CR adsorption process on the Cu0.5Co0.5Fe2O4 nanoparticles, while the Temkin isotherm best fitted the CR adherence on the Cu0.5Co0.5Fe2O4 nanoparticles. All data suggested that the adsorption of CR on the Cu0.5Co0.5Fe2O4 nanoparticles followed the mono-multilayer hybrid chemisorption mechanism. In addition, as the pH increased from 2 to 10, the adsorption capacity of the Cu0.5Co0.5Fe2O4 nanoparticles for CR decreased, indicating that an acidic environment was beneficial for the adsorption of CR on the Cu0.5Co0.5Fe2O4 nanoparticles. When recycling the Cu0.5Co0.5Fe2O4 nanoparticles after adsorbing CR, the relative adsorption rate was still 62.5% of the initial adsorption capacity after five cycles, revealing the reusability and promising applicability of Cu0.5Co0.5Fe2O4 nanoparticles in sewage treatment.

Electrooxidation of Alcohols on Mixed Copper–Cobalt Hydroxycarbonates in Alkaline Solution

AbstractMixed Cu‐Co hydroxycarbonates of the type (Cu1–xCox)2CO3(OH)2 have been synthesized over the whole range of Cu‐Co substitution (0≤x≤1) by co‐precipitation and their electrocatalytic activity in the oxidation reactions of ethanol (EOR), ethylene glycol (EGOR) and glycerol (GOR) in alkaline environment was evaluated to retrieve composition–activity correlations. Generally, cobalt incorporation led to higher activities for the alcohol oxidation (AOR) compared to the Cu‐only material and the results are compared with the competing oxygen evolution reaction (OER). On the Cu‐Co hydroxycarbonates, the electrooxidation of vicinal alcohols such as glycerol and ethylene glycol requires lower overpotentials than EOR and OER. Cu leaching from the hydroxycarbonate structure was observed in the presence of vicinal alcohols. The impact of chemical and electrochemical leaching of copper from the catalysts has been studied. The chemically leached catalyst was found to show increased AOR activity compared to other hydroxycarbonates, enabling the formation of larger amounts of formic acid during GOR measured in a circular flow cell electrolyzer. The results highlight that Cu‐Co hydroxycarbonates can be used as precursors to generate electrocatalytically active materials from Cu‐Co hydroxycarbonates for the AOR in alkaline solution.

Electrodeposition of Cobalt‐Copper Oxides Decorated with Conductive Polymer for Supercapacitor Electrodes with High Stability

AbstractHere, we report about the synthesis of Cobalt‐Copper (CC) mixed oxides prepared by electrodeposition and thermal annealing, and coated with PEDOT:PSS (CCP) for supercapacitor electrodes. The electrodes’ morphology and electrochemical performance were investigated by combining XRD, XPS, SEM, cyclic voltammetry, and galvanostatic charge/discharge tests. The initial capacity of the CC electrode was 26 mAh/g at a scan rate of 5 mV/s with a coulombic efficiency of 92 %. The CC electrode featured a capacity retention of 81 % at a constant current density of 1 A/g after 5000 cycles. CCP electrodes slightly reduced the specific capacity but increased both coulombic efficiency and cyclic stability. CCP1 electrode featured a specific capacity of 21 mAh/g at 5 mV/s scan rate with better coulombic efficiency 95 % along with capacity retention of 92.3 % over 5000 cycles. Increasing the amount of PEDOT:PSS lowered the CC electrodes’ specific capacity, but significantly improved the capacity retention up to 100 %.

Synthesis and characterization of mixed ternary transition metal ferrite nanoparticles comprising cobalt, copper and binary cobalt–copper for high-performance supercapacitor applications

Metal ferrites have outstanding electrochemical characteristics owing to the numerous oxidation states of the metal ions, making them promising materials for addressing both sustainable energy conversion and storage and growing environmental issues. Therefore, three nanocrystallites transition metal ferrites, CoFe2O4, CuFe2O4 and Co/CuFe2O4, were synthesized using citrate precursors and used as electrode materials for supercapacitor applications. Mixed transition metal ferrite nanoparticles were characterized by Fourier transform infrared (FT-IR), scanning electron microscope (SEM) complemented with energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Raman spectroscopy and thermal analysis (TGA). The findings illustrated the formation of a single-phase spinel ferrite as proved from XRD data. In addition, the particle shape and particle size obtained from TEM analysis revealed that the as-synthesised nanomaterial exhibited spherical shape with a size ranging from 30 to 50 nm. The result demonstrated that while using a three-electrode configuration, the electrochemical performance of the ferrite nanoparticles achieved a remarkable maximum specific capacitance of 893 Fg−1 at a scan rate of 5 mV s−1. At a current density of 1 Ag−1, Co–Cu ferrite exhibited outstanding cycling stability for 3000 cycles with 90% capacity retention. Based on the aforementioned data, it can be considered that the remarkable electrochemical performance of the Co–Cu ferrite nanocomposites can be considered as promising materials to be used for supercapacitor electrodes.

Bimetallic Cobalt-Copper Nanoparticle-Decorated Hollow Carbon Nanofibers for Efficient CO2 Electroreduction.

Bimetallic materials are one of the most promising catalysts for the electrochemical reduction of CO2, but there are still many challenges to be overcome on the route to industrialization. Herein, a series of carbon nanofiber-supported bimetallic cobalt–copper catalysts (CoxCuy/CFs) are designed and constructed through the electrospinning technique and a subsequent pyrolysis procedure. Small-sized Co–Cu nanoparticles are homogenously distributed on the porous carbon nanofibers, which can significantly improve the utilization rate of metal sites and greatly reduce the loading amount of metals. Moreover, different product distributions and catalytic performance can be obtained in CO2 reduction via adjusting the metal proportion of CoxCuy/CFs. Especially, Co3Cu/CFs can bring forth a 97% total faradaic efficiency (FE) of CO (68%) and HCOOH (29%) at –0.8 VRHE cathode potential in 0.5 M KHCO3 electrolyte. Furthermore, the hierarchical pores can firmly confine the small Co–Cu nanoparticles and keep them from easy agglomeration during electrolysis, eventually leading to 60 h of stability for Co3Cu/CFs in CO2 electroreduction. This study might provide a facile and economic method to fabricate efficient bimetallic catalysts for CO2 electroreduction and other electrocatalysis applications.

Cobalt–Copper Nanoparticles on Three-Dimensional Substrate for Efficient Ammonia Synthesis via Electrocatalytic Nitrate Reduction

Ammonia (NH3) is a valuable chemical for fertilizer production and for use as an effective hydrogen carrier. Electrocatalytic nitrate reduction has recently received great attention as an alternative for NH3 synthesis due to its kinetically favorable reaction. However, this promising strategy suffers from low Faradaic efficiency (FE) at large current density (>100 mA cm–2) and low nitrate concentrations because of the competing hydrogen evolution reaction. Herein, we report a catalyst consisting of earth-abundant cobalt–copper (Co1–xCux) nanoparticles supported on a three-dimensional substrate for efficient and selective NH3 synthesis via electrocatalytic nitrate reduction. Typically, the optimized Co0.5Cu0.5 catalyst performs at a high NH3 Faradaic efficiency (FE) of over 95% at −0.03 V with NH3 partial current density of ∼176 mA cm–2 at 50 mM nitrate, which is 7.3- and 1.7-fold higher than that of pure Co and Cu counterparts. Importantly, replacing Co with Cu enables the tuning of onset potential on Co catalyst maintaining high selectivity toward NH3. A stability test over 12 cycles confirmed the long-term operation of this catalyst. This work offers a facile strategy for tuning the catalyst’s elemental composition to attain a desired electrocatalytic activity.