Ni-Co Alloy Research Articles

Hollow engineering in CoNi@Air@C@MoS2 multicomponent composites derived from bimetallic CoNi Prussian blue analogs for ultra-wide bandwidth and strong electromagnetic wave absorption

In recent years, two-dimensional layered transition metal dichalcogenides-based multicomponent composites (MCCs) acting as electromagnetic wave (EMW) materials have received intensive investigations. However, the vulcanication of metal greatly hindered their enhancement of EMW absorption performances (EMWAPs). Herein, a combined metal-organic frameworks-derived and hydrothermal strategy was presented to produce yolk-shell structure (YSS) CoNi@Air@C@MoS2 MCCs. The results showed that the thermal and hydrothermal treatments resulted in the generation of YSS and two-dimensional MoS2 nanosheets, which maintained the original morphology of CoNi Prussian blue analogues. The protection of thick C layer well inhibited the vulcanization of inner CoNi alloy. The formed sheet-like MoS2 further optimized impedance matching characteristics, which led to the satisfactory EMWAPs of CoNi@Air@C@MoS2 MCCs. Furthermore, the EMWAPs could be further improved by optimizing the Ni:Co atom ratios CoNi@Air@C@MoS2 MCCs, which stemmed from their boosted impedance matching performances, EMW attention and polarization loss abilities. The absorption bandwidth and reflection loss values for YSS CoNi@Air@C@MoS2 MCCs are 8 GHz and −60.83 dB, which covered almost all C-Ku bands. In general, our research work provided a valid strategy to produce YSS magnetic CoNi@Air@C@MoS2 MCCs with high efficiency, which well avoided the vulcanization of metal nanoparticles, made best of hollow engineering and atomic ratio optimization strategy to boost the comprehensive EMWAPs.

Pinning-effect single-atom NiCo alloy embedded graphene-aerogel in electro-fenton process for rapid degradation of emerging contaminants

Inspired by the growing development of dual single-atom catalysts (SACs), a bimetallic single-atom alloy (SAA) based macro-assembled graphene aerogel (MAGA) was synthesized in this study. The single-atom NiCo alloy-based graphene aerogel (i.e., NiCo/GO aerogel) with pinning effect was used as a sustainable cathode material in an in-situ H2O2 generation system (i.e., electro-Fenton (EF) process). The atomic structure of NiCo/GO aerogel was identified by the combined microscopic and spectroscopic techniques. The SAA cathode exhibited a remarkable catalytic activity towards the two-electron-dominated oxygen reduction reaction (ORR) with the EF process for wastewater treatment. The energy consumption was calculated to be around 0.660 kW·h/t for treatment of water containing 2 mg L−1 ibuprofen (IBU). Density functional theory (DFT) analysis revealed the specific roles of the dual-functional NiCo SAA in the GO aerogel cathode, i.e., the Co sites more preferentially adsorb O2 molecules for H2O2 generation while the Ni sites function as the active sites for H2O2 dissociation and activation. The research findings shed light on the controlled synthesis of SAAs for advanced catalysis and its potential application in the treatment of emerging organic contaminants for water safety and pollution control.

In-situ constructing ultrafine NiCo alloy confined in LDH nanoflower for efficient selective hydrogenation of furfural

Directional activation of oxygen-containing groups is a crucial challenge in the catalytic conversion of renewable biomass to high-value products. Herein, we fabricated uniform dispersed NiCo alloy nanoparticles by direct reduction flower-like layer double hydroxides (LDHs) precursors. The as-obtained Ni2Co1AlO exhibited outstanding yield (97.6 %) of tetrahydrofurfuryl alcohol (THFOL) in furfural hydrogenation, which is significantly superior to those of monometallic Ni-based (75 %) and Co-based (0 %) LDH catalysts and even higher than the most noble metal catalysts. The Ni2Co1AlO showed robust stability, e.g., the catalyst can be recycled up to 10 times without loss of its conversion and selectivity, which is attributed to the ultra-dispersed metal cations in layers and the confined effect of metal oxides. Characterizations and theoretical calculations demonstrate that alloying Ni with Co can downshift the d-band center of Ni in NiCo alloys, which facilitates the H* desorption to improve hydrogenation activity. The unique electronic interactions between Ni and Co facilitated the parallel adsorption of furfural while reduced the energy barriers of the furan ring hydrogenation, promoting the production of THFOL. This work provides a promising strategy of tailoring d-band center, which can shed light on the design of heterogeneous catalysts.

Nanoconfined Magnetic Network Constructed by a NiCo Alloy Doped Interconnected Carbon Nanotube toward Enhanced Electromagnetic Wave Absorption Performance

Nanoconfined Magnetic Network Constructed by a NiCo Alloy Doped Interconnected Carbon Nanotube toward Enhanced Electromagnetic Wave Absorption Performance

N‐Doped Carbon Nanofibers and Carbon Nanotubes‐Encapsulated CoNi Alloy as Highly Active Oxygen Reduction Catalysts for Direct Methanol Fuel Cells

The slow oxygen reduction kinetics of direct methanol fuel cell (DMFCs) are one of the limiting factors affecting its application. Therefore, exploring nonprecious catalysts with high activity and methanol resistance is urgently needed. Herein, zeolitic imidazolate framework‐8 particles are first blended with different proportions of metal salts (Ni as well as Co) and further electrospun to obtain a nanofiber precursor. After pyrolysis treatment, a composite catalyst (CoNi@N‐CNFs) with a highly dispersed CoNi alloy phase supported by porous N‐doped carbon nanofiber and carbon nanotube is prepared. The surface electronic structure can be reasonably adjusted by optimizing the doping ratio of Ni and Co. The CoNi@N‐CNFs shows high oxygen reduction activity and methanol resistance. Half‐wave potential and the onset potential of Co1Ni1@N‐CNFs (Co: Ni mole ratio = 1:1) are 0.79 and 0.87 V. Additionally, Co1Ni1@N‐CNF‐modified DMFC endows a high power density (24.07 mW cm−2), which is close to Pt/C‐based DMFC (27.59 mW cm−2). Rich active sites, large specific surface area, and synergy between CoNi alloy and N configuration of CoNi@N‐CNFs effectively accelerate electron transfer, resulting in the superior catalytic activity. This work provides a new strategy to design effective 1D oxygen reduction reaction catalysts in fuel cells.

Study of the Synthesis of Multi-Cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Co-Ni-O Aerogels and Their Catalytic Activity in the Dry Reforming of Methane.

Dense multi-cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Ni-Co-O oxide aerogels were prepared by epoxide-driven sol-gel synthesis. Catalysts for dry reformation of methane, Sm2O3/Co, Sm2O3/Ni, Al2O3/Co, Al2O3/Ni, Al2O3/Co, and Ni were prepared by reduction of aerogels with hydrogen and their catalytic activities and C-deposition during dry reformation of methane were tested. Catalytic tests showed high methane conversion (93-98%) and C-deposition (0.01-4.35 mg C/gcat.h). The highest content of C-deposits after catalytic tests was determined for Al2O3/Co and Al2O3/Ni catalysts, which was related to the formation of Al alloys with Co and Ni. A uniform distribution of Co0 and Ni0 nanoparticles (in the form of a CoNi alloy) was found only for the Al2O3/Co and Ni catalysts, which showed the highest activity as well as low C deposition.

FeCo alloy nanoparticles supported on N-doped mesoporous carbon spheres for effective degradation of antibiotics and industrial dyes

Iron (Fe) is widely recognized for its effectiveness in the Fenton reaction and is commonly used in wastewater treatment. However, exploring other metals in similar Fenton-like reactions has been relatively limited. FeCo alloy nanoparticles (NPs), anchored on nitrogen-doped mesoporous carbon spheres (FeCo/NMCS), have been effectively synthesized and used as a Fenton-like catalyst in wastewater treatment under alkaline conditions. The NMCS exhibited spherical with an average diameter of 488.1 nm, while the FeCo alloy NPs, uniformly distributed over the NMCS, had an average diameter of 8.2 nm. The mesopores served as anchoring points for the NiCo alloy NPs, effectively preventing their possible agglomeration. The NMCS was composed of 3.91 wt% nitrogen. With 30 mg of FeCo/NMCS and 25 mM H2O2, more than 92% of tetracycline hydrochloride (TC) was degraded within 35 min at pH levels 7, 9, and 11. The remarkable degradation rate was attributed to the dual active sites present in the FeCo alloys. The rapid degradation of TC, even at pH 11, indicates the potential of FeCo/NMCS as a valuable solution for wastewater treatment under alkaline conditions. Industrial reactive (Y145, R195, B222A) and disperse dyes (O30, R167, B79) with a concentration of 10 ppm were degraded within 20 min when using 10 mg of the FeCo/NMCS catalyst and 25 mM H2O2 at pH 9. After five consecutive TC degradation cycles at pH 7 and 9, the FeCo/NMCS demonstrated consistent performance, emphasizing its reusability. FeCo/NMCS provides a promising solution to pollution control and wastewater treatment with stability, superior catalytic activity, magnetic separability, and recyclability.

Metal–organic framework–derived trimetallic particles encapsulated by ultrathin nitrogen-doped carbon nanosheets on a network of nitrogen-doped carbon nanotubes as bifunctional catalysts for rechargeable zinc–air batteries

Economical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalysts with high activity aimed at replacing precious metal catalysts for rechargeable zinc-air batteries (ZABs) must be developed. In this study, a multiple hierarchical-structural material is developed using a facile dielectric barrier discharge (DBD) plasma surface treatment, solvothermal reaction, and high-temperature carbonization strategy. This strategy allows for the construction of nanosheets using nitrogen-doped carbon (NC) material-encapsulated ternary CoNiFe alloy nanoparticles (NPs) on a network of NC nanotubes (NCNTs), denoted as CoNiFe–NC@p–NCNTs. Precisely, the presence of abundant CoNiFe alloy NPs and the formation of M–N–C active sites created by transition metals (cobalt, nickel, and iron) coupled with NC can provide superior OER/ORR bifunctional properties. Moreover, the prepared NC layers with a multilevel pore structure contribute to a larger specific surface area, exposing numerous active sites and enhancing the uniformity of electron and mass movement. The CoNiFe0.08–NC@p–NCNTs show remarkable dual functionality for electrochemical oxygen reactions (ORR half-wave potential of 0.811 V, limiting current density of 5.73 mA cm−2 measured with a rotating disk electrode at a rotation speed of 1600 rpm, and OER overpotential of 351 mV at 10 mA cm−2), which demonstrates similar ORR performance to 20 wt% Pt/C and better OER performance than the commercial RuO2. A liquid ZAB prepared using the proposed material has excellent bifunctionality with an open-circuit voltage of 1.450 V and long-term cycling stability of 230 h@10 mA cm−2.

CoNi/MXene@CoNi/MXene microsphere/silicone rubber multilayered composites for ultra-broadband microwave absorption

2D transition metal carbide/nitride (MXene) nanomaterials have prospective applications in high-performance microwave absorption (MA). However, the excessively high permittivity, absence of magnetic loss, and susceptible oxidizability of MXene severely hinder the enhancement of its MA properties. Here, we used a facile organic solution–phase thermal decomposition method to prepare dielectric–magnetic MXene@CoNi nanocomposites with heterojunctions, which can effectively prevent the oxidation of MXene. Subsequently, the MXene@CoNi nanocomposites were integrated with magnetic CoNi alloys, MXene microspheres (MXene MPs), and a silicon rubber (SR) matrix to construct multilayered CoNi/MXene@CoNi/MXene MPs/SR composites by casting and curing. Benefiting from the multilayered structure and complementary effects of the dielectric and magnetic components, the multilayered CoNi/MXene@CoNi/MXene MPs/SR composites composed of matching, absorbing, and reflective layers showed a remarkable minimum reflection loss of −53.3 dB and an ultra-broad effective absorption bandwidth up to 11.12 GHz at a thickness of 2.96 mm. These results demonstrated the developed multilayered composites are promising candidates for high-performance MA. Our study provides new insights into the development of ultra-broadband MXene-based absorbent materials.

Effect of Fe on the oxidation behavior, electrical properties and microstructure of Co[sbnd]Ni protective coatings for metal interconnect layers in solid oxide fuel cells

CoNi and 5% Fe doping CoNi alloy coatings are prepared on SUS 430 substrates as interconnect protect layers for solid oxide fuel cells by electroplating. The electrical characteristics and oxidation resistance of interconnects are enhanced by the alloy coatings after they are oxidized in air at 800 °C for 1000 h and the Co-Ni-Fe alloy coatings showing the better effect. Cr is unable to diffuse outward owing to the multi-layer oxidation structure. Addition of Fe to CoNi alloy coatings leads to the formation of a (Fe,Co,Ni)3O4 spinel layer with lower activation energy and stronger ability to restrict oxygen diffusion inward.

Aqueous Phase Hydrodeoxygenation of Phenol on Hβ Zeolite Supported NiCo Alloy Catalysts

Aqueous Phase Hydrodeoxygenation of Phenol on Hβ Zeolite Supported NiCo Alloy Catalysts

Coupling phyllosilicate and NiCo alloy nanoparticles on sepiolite to enhance stability for hydrogen production by ethanol steam reforming

For hydrogen production from ethanol steam reforming (ESR), The NiCo alloy immobilized on sepiolite (SEP) support by a phyllosilicate precursor was deemed as an effective strategy to improved catalyst stability. The Ni/Co ratio was regulated to optimized the ESR reactivity of the bi-metallic catalysts prepared by the NH4F assisted urea hydrothermal method. The synergy effect of NiCo alloy with a Ni-rich surface on ESR reactivity and anti-deactivation was investigated. The 5Ni10Co/SEP catalyst presented the highest conversion (99.4 %) and H2 yield (68.2 %) at 700 °C, which was benefited from the downsized nanoparticle size and strong metal-support interaction. The proposal structure-activity relationship suggested that the NiCo alloy was exsolved from the phyllosilicate precursor grafted on SEP framework, providing an excellent mitigation for metal sintering. In addition, the synergy of NiCo alloy was elaborated by a combination of enhanced ethanol adsorption/dissociation on Ni sites and restrained methanation on Co sites, offering a 50 h catalyst stability during ESR consisting of the ethanol dehydration route. The developed NiCo alloy catalyst based on SEP support with phyllosilicate precursor provided a prospect on the application to H2 production from ESR over the bimetallic catalysts with simple preparation, high economy and structure stability.

Ni-Co alloy supported on CeO2 by SiO2 encapsulation for dry reforming of methane

Dry reforming of methane (DRM) is a highly endothermic reaction that needs harsh condition of high temperature for syngas production, which is challenged by developing catalysts with properties of anti-sintering and low carbon deposition. This work synthesized confined catalysts of (Co-Ni/CeO2)@SiO2 for DRM reaction. The catalysts possessed multifunction including size and alloy effects, metal-support interaction and confinement effect, which contributed to high rates of CH4 and CO2, marginal sintering of NiCo alloy and trace carbon deposition. The (3Ni-3Co/CeO2)@SiO2 catalyst reached rates as high as 4.74 mmol/(gNi·s) and 5.57 mmol/(gNi·s) for CH4 and CO2, respectively, at 1023 K. The rates were keeping stable for at least 36 h on stream. The characterizations of used samples revealed the limited size change of NiCo alloy and the low carbon deposition. The work provides valuable guidance for developing stable catalysts for DRM and other high temperature reactions.

Surfactant-assisted synthesis of NiCo alloy with specific nanopore architecture as a bifunctional electrocatalyst for rechargeable zinc-air batteries

Designing the effective active sites and reaction areas of catalytic materials is important for the development of bifunctional electrocatalysts for zinc-air batteries (ZABs). In this paper, a catalyst with a uniform nanopore structure (noted as NiCo-PS) was one-pot synthesized by using transition metals nickel and cobalt as catalytic active components, sucrose as a carbon source, and triblock copolymers as a soft template. The N2 absorption and desorption isotherms curves show that the pore size distribution of NiCo-PS modified by surfactant is mainly in 3.6 nm range. NiCo-PS exhibits exceptional bifunctional electrocatalysis due to its effective triple-phase reaction interface from its mesoporous structure, with a positive half-wave potential of 0.758 V for ORR and a low overpotential of 390 mV at 10 mA ⋅ [Formula: see text] for OER. Furthermore, the rechargeable ZABs with the NiCo-PS catalyst exhibit a high open-circuit voltage of 1.31 V, a significant peak power density of 105 mA ⋅ [Formula: see text] at 0.56 V, and good stability throughout 270 h testing. This result offers valuable insights for designing catalysts that enhance the active region of the reaction within the cathodes of ZABs and hold significant promise for practical applications.

Enhancing oxygen reduction reaction performance through eco-friendly chitosan gel-assisted molten salt strategy: Small NiCo alloy nanoparticles decorated with high-loading single Fe-NX

We developed an effective and eco-friendly strategy using chitosan gel-molten salt to achieve high loading (2.23 At. %) of single Fe-NX as assistive active sites. These sites were combined with small NiCo alloy NPs distributed on porous carbon aerogels to boost the ORR performance. The FeSAs-NiCo alloy@N-C sphere exhibits exceptional mass activity and specific activity of 3.705 A.mg−1 and 8.79 mA.cm−2(ECSA), respectively, at 0.85 V versus RHE. It has a superior onset potential of 1.08 V versus RHE, surpassing that of its nanoparticle Fe counterpart and NiCo alloy@N-C sphere. The significant improvement in ORR performance of the FeSAs-NiCo alloy@N-C sphere could be attributed to the positive effects of increased lattice strain due to the single atoms of Fe-NX hybridized with small NiCo alloy NPs. The chitosan gel-assisted molten salt strategy and assistive active sites of Fe-NX hybridized with NiCo alloy NPs regulate the electronic properties of the FeSAs-NiCo alloy@N-C sphere, both geometrically via lattice strain mismatch and electronically through shifting of the d-band center. This could influence the binding energies for oxygen and/or oxygen reduction intermediate adsorption/desorption. The additional improvement in the ORR performance of the FeSAs-NiCo alloy@N-C sphere also benefits from having a lower electrochemical activation energy.

Tailoring competitive adsorption sites of hydroxide ion to enhance urea oxidation-assisted hydrogen production

Alloys with bimetallic electron modulation effect are promising catalysts for the electrooxidation of urea. However, the side reaction oxygen evolution reaction (OER) originating from the competitive adsorption of OH− and urea severely limited the urea oxidation reaction (UOR) activity on the alloy catalysts. This work successfully constructs the defect-rich NiCo alloy with lattice strain (PMo-NiCo/NF) by rapid pyrolysis and co-doping. By taking advantage of the compressive strain, the d-band center of NiCo is shifted downward, inhibiting OH− from adsorbing on the NiCo site and avoiding the detrimental OER. Meanwhile, the oxygenophilic P/Mo tailored specific adsorption sites to adsorb OH− preferentially, which further released the NiCo sites to ensure the enriched adsorption of urea, thus improving the UOR efficiency. As a result, PMo-NiCo/NF only requires 1.27 V and −57 mV to drive a current density of ±10 mA cm−2 for UOR and hydrogen evolution reaction (HER), respectively. With the guidance of this work, reactant competing adsorption sites could be tailored for effective electrocatalytic performance.

Phase transition Ni-Co-Ca-O bifunctional catalysts for high and stable hydrogen production from sorption enhanced steam methane reforming

Sorption enhanced steam methane reforming (SESMR) is an effective method to improve the efficiency of hydrogen production from methane reforming while fixing CO2 to reduce carbon emissions. However, the deactivation of adsorbents during high temperature recycling limits the utilization of SESMR. In this paper, by combining the phase transition process of Ca-Co-O species and Ni-Co alloy, we prepared a series of Ni-Co-Ca-O bifunctional catalysts for SESMR hydrogen production. The 1Ni4.5Co4.5CaO catalyst exhibited high catalytic activity in the SESMR reaction with hydrogen concentration exceeding 99.6 % and complete methane conversion. The catalyst also showed high stability in 50 cycle experiments with no significant reduction in hydrogen production and CO2 uptake performance. The Ni-Co-Ca-O bifunctional catalysts consisted of NiO and Co-Ca-O species, by analyzing the fresh and reacted catalysts, the mechanism of the catalyst with high catalytic activity and stability was revealed. Firstly, the catalyst formed Ni-Co alloy and CaO adsorbent by a reduction reaction, and then the SESMR hydrogen production reaction was carried out. After the complete conversion of CaO to CaCO3, the catalyst was re-formed into NiO and Co-Ca-O species by introducing O2 in the regeneration reaction to carry out a new cycle of reduction → hydrogen production. The synergistic interaction between the Ni-Co alloy enhanced the methane reforming and water gas shift reaction, leading to an increase in hydrogen production and methane conversion. The phase transition of Co from Co-Ca-O species to Ni-Co alloy and back to Co-Ca-O species inhibited the sintering of CaO, which significantly enhanced the cyclic stability of the catalyst. The results of this study are expected to provide a new pathway for the design of SESMR bifunctional catalysts.

Cycad-leaf-like crystalline-amorphous heterostructures for efficient urea oxidation-assisted water splitting

Developing efficient bifunctional catalysts for urea oxidation reaction (UOR)/hydrogen evolution reaction (HER) is important for energy-saving hydrogen production. Herein, a catalyst with crystalline-amorphous heterostructure supported by NiCo alloy on nickel foam (NiCoO-MoOx/NC) is reported for the first time. Through simple molybdenum salt etching, 2D NiCo alloy nanosheets are transformed into a unique 3D cycad-leaf-like structure with a super-hydrophilic surface. Simultaneously, the synergistic effect between crystalline NiCoO and amorphous MoOx improves the UOR and HER activity, merely requiring 1.28 V and −45 mV potentials to reach ±10 mA cm−2, respectively. Particularly, the UOR kinetics of NiCoO-MoOx/NC is enhanced significantly compared to that of NiCoO/NC. The electronic structure of NiCoO is modified by MoOx, enabling the rapid generation of NiOOH and CoOOH active species, which would accelerate the synergistic electrocatalytic oxidation of urea molecules. This work inspires the design of highly active and stable bifunctional catalysts for urea assisted H2 production.

Study of the Use of Gas Diffusion Anode with Various Cathodes (Cu-Ag, Ni-Co, and Cu-B Alloys) in a Microbial Fuel Cell

Advancing microbial fuel cell (MFC) technologies appears to be a crucial direction in bolstering wastewater treatment efforts. It ensures both energy recovery (bioelectricity production) and wastewater pre-treatment. One of the problems in the widespread use of MFCs is the generation of a small amount of electricity. Hence, a pivotal concern revolves around enhancing the efficiency of this process. One avenue of investigation in this realm involves the selection of electrode materials. In this research, a carbon-based gas diffusion electrode (GDE) was used as the anode of MFC. Whereas for the cathode, a copper mesh with various catalysts (Cu-B, Ni-Co, and Cu-Ag) was used. This research was conducted in glass MFCs with the sintered glass acting as a chamber separator. This research was conducted for various electrode systems (GDE/Cu-Ag, GDE/Ni-Co, and GDE/Cu-B). This study analyzed both the electrical parameters and chemical oxygen demand (COD) reduction time. In each case (for each electrode system), bioelectricity production was achieved. This work shows that when GDE is used as the anode and Cu-B, Ni-Co and Cu-Ag alloys as the cathode, the most efficient system is the GDE/Cu-Ag system. It ensures the fastest start-up, the highest power density, and the shortest COD reduction time.

Ti3C2Tx/PANI/CoNi as a ternary composite material unveiling excellent microwave absorption performance

Ti3C2Tx MXene material exhibits exceptional dielectric properties and a distinct layered structure, making it a noteworthy microwave absorbing material. However, its microwave absorption performance is limited due to poor impedance matching and a single loss mechanism. To address these issues, this work develops a solvothermal method to introduce the magnetic component CoNi alloy and generate organic polymer PANI through in-situ polymerization, resulting in the preparation of Ti3C2Tx/PANI/CoNi ternary composites that significantly improve impedance matching and microwave absorption performance. The microwave absorption properties of the binary and ternary composites are compared, and the superior performance of the ternary composites is emphasized. Among the ternary composites, M-P-CN 3:1:8 exhibited an excellent microwave absorption performance, demonstrating a minimum RL value of −55.48 dB and an effective absorption bandwidth of 5.1 GHz at a thickness of 2.0 mm. The synergistic effect of multiple loss mechanisms, multilayer structures, and multiple interfacial polarization methods further contribute to the enhanced microwave absorption performance of ternary composites. This study provides a straightforward method for synthesizing and designing multi-component composite absorbing materials based on MXene.