Ni-Co Alloy Research Articles

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.

Boosting primary amines renewable tandem synthesis via defect engineering of NiCo alloy

AbstractReductive amination of biomass aldehydes is a vital process to synthesize chemical intermediates primary amine, but the selectivity is severely compromised by the self‐condensation of highly reactive imine intermediates. Herein, we proposed a solution by manipulating the adsorption configuration of secondary imine via defect engineering. Specifically, a gradient reduction strategy was used to adjust the driving force of NiCo alloy crystallization, thus motivating the formation of metal vacancy clusters. The primary amine selectivity was raised from 70.9% to 95.1% with defect concentration increased from 36.1% to 42.5% on catalysts. In situ fourier transform infrared spectroscopy (FTIR) and density functional theory demonstrated metal vacancy clusters induced remarkable NiCo electron transfer, which strengthened electronic coupling between secondary imine with catalyst, resulting in a flat configuration that was conducive to CN bond breakage to guarantee smooth conversion into primary amines. This catalyst exhibited potential real‐life application prospects for its low cost, universality in reductive amination of various aldehydes, and long‐life reusability.

Catalytic conversion of crude oil to hydrogen by a one-step process via steam reforming

This work presents a multi-functional NiCoCe-based catalyst for crude oil steam reforming for hydrogen production. Arab Light (AL) and Arab Extra Light (AXL) were centrifuged to reduce the asphaltenes and sequentially steam reformed in a fixed bed reactor. Results showed that the NiCoCe catalyst was stable and highly selective under reaction conditions and in cyclic operation. The physicochemical properties of the catalyst were determined via inductively coupled plasma–optical emission spectrometry, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The high dispersion of the NiCo alloy on a Mg–Al support was crucial for ensuring the hydrocarbon reforming in the presence of heteroatomic species.

Pt-on-CoNi alloy nanoparticles supported on N and P co-doped graphene catalyst for highly efficient hydrogen evolution by acidic water electrolysis

The multimetallic catalysts with adjustable electronic structures and synergy effect between various metals compared to monometallic catalysts are widely applied in electrocatalysis. Herein, graphene is doped with N and P to prepare rGNP support, then a trimetallic PtCoNi/rGNP catalyst is prepared via simple impregnation and galvanic replacement reaction methods. Pt is highly dispersed on the CoNi alloy nanoparticles (NPs) on rGNP for PtCoNi/rGNP. Based on various characterization techniques and electrochemical testing results such as ICP-OES, XRD, XPS, TEM, HRTEM, STEM, STEM-EDX elemental mapping and line-scanning, it confirms the nanostructure of PtCoNi/rGNP (Pt-on-CoNi alloy). The overpotential of PtCoNi/rGNP for hydrogen evolution (HER) via acidic water electrolysis at 100 mA cm−2 is 15 mV, lower than commercial Pt/C (Pt/C) (66 mV). The Tafel slope of PtCoNi/rGNP is 6.46 mV dec−1, smaller than that of Pt/C (17.15 mV dec−1). The overpotential at 10 mA cm−2 only increases with 3.2 mV (reaching 13.2 mV) after a long time stability testing of 72 h, still lower than Pt/C (20 mV), indicating that it has high catalytic activity and stability. This work not only reveals the synergistic effect mechanism of noble metal-on-non-noble metal for the HER, but also provides a new strategy to develop efficient and highly stable catalysts for the HER.