Cobalt Boride Research Articles

Cooperative roles of water and metal-support interfaces in the selective hydrogenation of cinnamaldehyde over cobalt boride catalysts

Cooperative roles of water and metal-support interfaces in the selective hydrogenation of cinnamaldehyde over cobalt boride catalysts

Evaluation of thermal plasma-synthesized cobalt boride nanoparticles as efficient water-splitting catalysts

Herein, cobalt boride nanoparticles are synthesized using the thermal plasma process and investigated in their performance as electrocatalysts for water splitting. The products show efficient electrocatalyst performance for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline electrolyte (1 M KOH). The size distribution of the products, CoB and Co2B, is between 5 and 15 nm, which is decreased by reducing the flow rate of plasma-forming gas. The results reveal that the size of the particles could be controlled by changing the flow rate of the plasma-forming gas. Furthermore, the cobalt boride nanoparticles with high crystallinity could be synthesized through a one-step process without the post-treatment process. The products achieve an overpotential of 355 mV at a current density of 10 mA/cm2 and a Tafel slope of 49 mV/dec in the OER measurement, and their performance is more efficient than that of the cobalt-based catalysts reported to date. In contrast, the products exhibit a relatively high Tafel slope of 92 mV/dec and a low active surface area of 1.2 mF/cm2 in the HER measurement. However, their long-term stable performance is maintained for OER and HER at ± 10 mA/cm2 for 40 h. Thus, cobalt boride nanoparticles are a promising material for the anode of water-splitting electrodes.

Pomegranate-like Ni-doped cobalt boride implanted in B, N-doped carbon nanocages for enhanced electrochemical oxygen evolution

The development of efficient and stable transition metal boride electrocatalysts for oxygen evolution reaction (OER) is critical for energy conversion and environmental protection. Herein, we synthesized B, N-doped carbon layer encapsulated the Ni-doped CoxB nanocages electrocatalyst (denoted as Ni-CoxB@BNC) via a high-temperature boronizing, derived from Ni-doped cobalt-based zeolite imidazole frame (NiCo-ZIF), toward enhanced electrochemical alkaline oxygen evolution reaction. The Ni-CoxB@BNC electrocatalyst synthesized at 550 °C exhibits excellent OER activity with a low overpotential of 274 mV and a Tafel slope of 80 mV dec−1 at a current density of 10 mA cm−2, which is better than precious metal RuO2. The synergistic effect between B, N-doped carbon layer and Ni-doped CoxB in Ni-CoxB@BNC leads to higher OER catalytic activity. The B, N-doped carbon layer provides additional active sites, which accelerates charge transport and enhances the conductivity of Ni-CoxB@BNC during OER. In addition, it also protects the pomegranate seed-like Ni-CoxB nanoparticles inside, improving the stability of the Ni-CoxB@BNC material. This work unambiguously elucidates the design and preparation strategy of transition metal boride implanted B, N-doped carbon nanocage electrocatalysts derived from controlled bimetallic ZIF precursor.

A New Approach to the Synthesis of Nanocrystalline Cobalt Boride in the Course of the Thermal Decomposition of Cobalt Complexes [Co(DMF)6]2+ with Boron Cluster Anions

In the course of the study, nanocrystalline cobalt monoboride was prepared by thermal decomposition of precursors [Co(DMF)6][An], where [An] = [B12H12]2- (1), [trans-B20H18]2- (2) or [B10Cl10]2- (3) in an argon atmosphere. Three new salt-like compounds 1-3 were prepared when Co(NO3)2 was allowed to react with (Et3NH)2[An]. Compound 1 is new; the structures of compounds 2 and 3 have been previously reported. Samples 1-3 were annealed at 900 °C in argon to form samples 1a-3a, which were characterized by single crystal XRD for 1 and powder XRD for 1-3. Powder XRD on the products showed the formation of BN and CoB for 1a in a 1:1 ratio; 2a gave a higher CoB:BN ratio but an overall decreased crystallinity. For 3a, only CoB was found. IR spectra of samples 1a-3a as well as X-ray spectral fluorescence analysis for 3a confirmed these results. The nanoparticular character of the decomposition products 1a-3a was shown using TEM; quite small particle sizes of about 10-15 nm and a quite normal size distribution were found for 1a and 2a, while the decomposition of 3 gave large particles with 200-350 nm and a broad distribution.

On The Efficacy of Cobalt Boride Coating on NMC-811 Cathode Under Vinylene Carbonate Additive, High Temperature and Air Shelving Conditions

Cobalt boride (CoB) is a novel coating material for high-voltage cathodes, which has demonstrated excellent protective capabilities for the NMC-811 cathode in the LiPF6-EC-EMC electrolyte. However, there is limited knowledge about its effect at high temperatures as well as in the second-generation electrolyte that contains the vinylene carbonate (VC) additive. In this work, the cycling performance of the CoB coated NMC-811 cathode was evaluated in EC-EMC-based electrolytes with and without VC using Li||NMC-811 coin cells at different temperatures. The CoB coating can effectively protect the NMC-811 cathode at room temperature without VC. But the protective capabilities of the CoB coating are slightly reduced in the presence of VC. Meanwhile, high temperature and air shelving both have a negative impact on the CoB coated material. Therefore, we conclude that the combination of CoB coating and VC additive is not beneficial to the NMC-811 cathode. High-temperature conditions can accelerate the decomposition of the electrolyte, causing the CoB coating to lose its protective capabilities. Air shelving can also reduce the protective capabilities of the CoB coating layer. Therefore, for CoB coated NMC-811 to fully release its long-cycle life performance, it is important to consider electrolyte formulation, and proper storage to optimize the long-cycle life performance of CoB coated NMC-811.

Reactive boride as a multifunctional interface stabilizer for garnet-type solid electrolyte in all-solid-state lithium batteries.

All-solid-state batteries are one of the most important game changers in electrochemical energy storage since they are free from the risk of leakage of hazardous flammable liquid solvents. Among the various types of solid-state electrolytes, Li7-xLa3Zr2-xTaxO12 garnets possess many desirable advantages to be considered a suitable candidate for lithium-ion batteries. However, their practical application has been hindered by premature short-circuits due to lithium dendrite growth, nonnegligible electronic conductivity and interfacial air sensitivity issues. Herein, we propose a multifunctional layer strategy to simultaneously address both the interface and electronic conductivity issues. With the help of a facile chemical process based on reactive cobalt boride, electron leakage was effectively blocked and the electrochemical performance/stability could be well maintained over extended cycles. The cobalt boride-coating layer also possessed an impressive Li metal wetting ability while sustaining a low interfacial resistance. A full cell paired with a commercialized cathode showed satisfactory performance with low overpotentials and a high specific capacity over 150 mA h g-1. Moreover, first-principle calculations further revealed the status of the rearrangement of the electron cloud behind the charge-density difference, and the nature of the low diffusion energy barrier of the reactive cobalt boride protective layer. Our strategy highlights the necessity of designing proper multifunctional layers in the garnet-type solid-state lithium-ion battery system.

In Vitro Transcriptome Analysis of Cobalt Boride Nanoparticles on Human Pulmonary Alveolar Cells.

Nanobiotechnology influences many different areas, including the medical, food, energy, clothing, and cosmetics industries. Considering the wide usage of nanomaterials, it is necessary to investigate the toxicity potentials of specific nanosized molecules. Boron-containing nanoparticles (NPs) are attracting much interest from scientists due to their unique physicochemical properties. However, there is limited information concerning the toxicity of boron-containing NPs, including cobalt boride (Co2B) NPs. Therefore, in this study, Co2B NPs were characterized using X-ray crystallography (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. Then, we performed 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) release, and neutral red (NR) assays for assessing cell viability against Co2B NP exposure on cultured human pulmonary alveolar epithelial cells (HPAEpiC). In addition, whole-genome microarray analysis was carried out to reveal the global gene expression differentiation of HPAEpiC cells after Co2B NP application. The cell viability tests unveiled an IC50 value for Co2B NPs of 310.353 mg/L. The results of our microarray analysis displayed 719 gene expression differentiations (FC ≥ 2) among the analyzed 40,000 genes. The performed visualization and integrated discovery (DAVID) analysis revealed that there were interactions between various gene pathways and administration of the NPs. Based on gene ontology biological processes analysis, we found that the P53 signaling pathway, cell cycle, and cancer-affecting genes were mostly affected by the Co2B NPs. In conclusion, we suggested that Co2B NPs would be a safe and effective nanomolecule for industrial applications, particularly for medical purposes.

Interfacial electronic heterostructure engineering of cobalt boride nanosheets toward broadband efficient electromagnetic absorption

Vigorous reflection loss (RL), wide bandwidth together with suitable absorption frequency band are key application indicators for cutting-edge electromagnetic (EM) absorbers to avoid EM pollution in the aerospace. However, the rational design of EM absorbers, especially for the integration of multiple properties, remains highly challenging. Here, we report a novel two-dimensional (2D) nanosheets-like heterostructure constructed by a molten salt-assisted dissolution-growth strategy and linked via strong interfacial electronic interactions, namely, cobalt boride (CoB) with boron, nitrogen co-doped carbon (CoB/BNC). Density functional theory (DFT) calculations demonstrate that stable heterointerfaces formed by strong interfacial electronic interactions are beneficial for enriching polarization effects, while contributing sufficient dielectric loss to boost the EM absorption (EMA) performance. Accordingly, the minimum RL (RLmin) of −70.76 dB and effective absorption bandwidth (EAB) of 4.72 GHz are simultaneously accomplished for CoB/BNC at the thickness of 3.48 mm. Moreover, radar cross section (RCS) simulation results confirmed that the as-prepared absorber coating could perfectly suppress the metal scattering sources in different directions. Generally, this work offers an ingenious engineering strategy for the precise synthesis of functional heterostructures, which holds great promise for developing innovative EMA materials in the aerospace.

In situ evolved defective TiO2 as robust support for CoB-catalyzed hydrolysis of NaBH4

Sodium borohydride (NaBH4) has been proposed to be a realizable hydrogen supplier for proton-exchange membrane fuel cell. Cobalt boride (CoB) is one of the most promising non-precious metal-based catalysts toward NaBH4 hydrolysis. In this work, we develop a facile method to synthesize defects-rich TiO2 supported CoB nanoparticles (CoB/TiO2-x). In this CoB/TiO2-x, an electronic metal-support interaction is induced by transferring electrons from the defective TiO2 to CoB to form electron-rich CoB particles, facilitating the hydrolysis of NaBH4. The as-synthesized CoB/TiO2-x catalyst shows a good catalytic performance with hydrogen generation rate of 3070 mL min−1 gCo−1 and activation energy of 57.03 kJ mol−1.

Fabricated noble-metal free Co2B/g-C3N4 photocatalyst with 2D/2D structure achieved remarkable water splitting performance from visible to near-infrared wavelengths

Developing noble-metal-free photocatalysts to address the challenges of high recombination rate of electrons and holes and poor optical response is high desirable for water splitting. Herein, cobalt boride (Co2B) nanosheets with amorphous phases ordered in short-range but disordered in long-range was fabricated, and coupled with graphic carbon nitride (CN) photocatalysts in the form of B(δ−)–Co(δ+)–N(δ−) bonding states through an in-situ chemical reduction method. The optimized Co2B/CN nanohybrids exhibited a H2 evolution rate of 56.86 μmol/h with the highest AQY up to 22.8 %, outperforming than that of Pt decorated CN. Theoretical calculation by DFT verify the characterization results and show that Co active sites on Co2B have better performance of adsorbing H atoms and desorbing hydrogen. The disordered structure of Co2B nanosheets contributed to water splitting performance by providing abundant active sites while metallic nature of Co2B facilitated electrons transfer and inhibited the recombination of electrons and holes. Moreover, theoretical calculation suggested that the high concentration of free carriers endowed Co2B with an resembled SPR effect, thereby increasing the light response of CN and triggering the reaction from visible-light region extended to the near-infrared region up to 800 nm.

Synthesis of Cobalt Boride Particles by Molten Salt Assisted Calciothermic Reduction

Synthesis of Cobalt Boride Particles by Molten Salt Assisted Calciothermic Reduction

Tuning the Catalytic Activity of Bifunctional Cobalt Boride Nanoflakes for Overall Water Splitting over a Wide pH Range

The world is in the process of transitioning towards a more sustainable energy future, with green hydrogen considered an attractive energy vector that can replace fossil fuel consumption, meeting global energy demands. To date, the most advanced method to produce green hydrogen is through water electrolysis using the residual supply of renewable energy. The current state-of-the-art catalysts used in electrolyzers are platinum-based metals and ruthenium/iridium oxides. The scarceness of these elements, combined with their high price, make these catalysts not economically viable for largescale production of hydrogen through water electrolysis. This study presents cobalt boride nanoflakes as materials to be used in both the anode and the cathode of an electrolyzer for electrochemical water splitting over a wide pH range. The cobalt boride nanoflakes were synthesized by the chemical reduction of CoCl2 using NaBH4 at three different concentrations to obtain CoB and Co2B nanoflakes. CoB nanoflakes exhibited both a higher specific surface area and greatest disparity in charge between B and Co, in comparison to Co2B. It was demonstrated that by tuning the properties of the cobalt boride nanoflakes, higher catalytic activities for both the hydrogen and oxygen evolution reaction can be achieved, showing good overall stability.

Self-supported nickel iron selenide@nickel cobalt boride core-shell nanosheets electrode for asymmetric supercapacitors

Optimizing the electrode structure and interface is a promising approach to achieve high energy density asymmetric supercapacitors. In this study, a core–shell heterostructure based on crystalline nickel iron selenide (NiSe2-Fe3Se4) and amorphous nickel cobalt boride (NiCoB) is for the first time in-situ fabricated on carbon cloth substrate though a hydrothermal approach, a selenization process, followed by a chemical precipitation method. In this well-defined hybrid material (denoted as NiSe2-Fe3Se4@NiCoB), the close combination of NiSe2-Fe3Se4 nanosheets core and NiCoB nanosheets shell results in a large specific surface area with rich open channels, and numerous crystalline/amorphous interfaces with regulated electronic structure. Owing to its unique hierarchical pore architecture and synergistic effect of dual battery-type materials, the resultant NiSe2-Fe3Se4@NiCoB electrode displays a specific capacity of 887.0C g−1 at 1 A g−1, wonderful rate retention (71.3% at 20 A g−1), and good cycling stability (86.4% after 5000cycles). Additionally, the assembled NiSe2-Fe3Se4@NiCoB//porous carbon asymmetric supercapacitor illustrates a remarkable energy density of 72.7 Wh kg−1 at 710.7 W kg−1, and exceptional cycling life with capacity retention of 91.1% over 20,000cycles.

Integrating trace ruthenium cluster with cobalt boride toward superior overall water splitting in neutral media

Cobalt boride which is an active bifunctional water splitting catalyst in alkaline media shows poor activity in neutral media. We found that trace ruthenium (Ru) cluster deposition (80 μg·cm−2) on cobalt boride by simple wet chemical reduction method can dramatically improve both its hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in neutral solution. The electron transfer from Co-B to Ru may result in the easier water dissociation step so as to facilitate the catalytic process. The resulting Ru@Co-B/Ni binder-free electrode could supply 10 mA cm−2 at overpotentials of 56 mV for HER and 280 mV for OER in 0.5 M phosphate buffer electrolyte. This work proposed a fruitful approach to advance the water splitting performance of transition metal boride in neutral media.

Zinc Doping Enhances the Electrocatalytic Properties of Cobalt Borides for the Hydrogen Evolution Reaction

Electrochemical water splitting requires new, low-cost cathode electrodes for the hydrogen evolution reaction to enable the worldwide implementation of electrolyzers. Cobalt borides are proposed as one of the most promising materials to overcome the limitations of the commercial electrocatalysts, but the catalytic activity still needs to be improved to be competitive. Here, we report that the introduction of zinc into cobalt boride to produce a ternary cobalt boride is an efficient route to further improve the catalytic activity towards the hydrogen evolution reaction (HER) of cobalt boride. The ternary Co-Zn-B was prepared by an easy chemical reduction method to achieve superior HER electrocatalytic performance with a lower overpotential than the homologous Co-B. The larger surface area, structural order, crystallization degree and, in particular, the different surface chemistry seem to be key factors for this improvement.

2D Amorphous Mo‐Doped CoB for Bidirectional Sulfur Catalysis in Lithium Sulfur Batteries

AbstractThe amorphous metal boride materials are attractive catalyst for advanced lithium sulfur batteries, but their catalytic mechanism remains unclear. Herein, 2D amorphous Mo‐doped cobalt boride (Co7Mo3B) is designed for the first time as bidirectional sulfur catalysis by rapid chemical reduction. The atom cluster structure of Co7Mo3B is revealed by theoretical calculation. Electron paramagnetic resonance test further confirms that Co7Mo3B has interstitial compound structure characteristics. Experimental results show that the porous 2D nanosheets structure and the interaction of Mo, B, Co atoms contribute to enhanced conductivity, high long‐chain lithium polysulfides affinity, and reversible Li2S nucleation and dissociation, thus accelerating LiPSs reduction and Li2S oxidation kinetics. In addition, the interstitial Co7Mo3B enables intercalation of Li and B during charging–discharging while keeping the structure stable. As a result, the S cathode with Co7Mo3B catalyst delivers good life (1000 cycles at 5 C), superior rate performance (10 C). Even at high sulfur areal loading of 6.79 mg cm–2 and electrolyte/sulfur ratio of 5 μL mg–1, the Co7Mo3B/S composite cathode still exhibits good areal capacity and capacity retention rate.

Rapid and Energetic Solid-State Metathesis Reactions for Iron, Cobalt, and Nickel Boride Formation and Their Investigation as Bifunctional Water Splitting Electrocatalysts

Metal borides have long-standing uses due to their desirable chemical and physical properties such as high melting points, hardness, electrical conductivity, and chemical stability. Typical metal boride preparations utilize high-energy and/or slow thermal heating processes. This report details a facile, solvent-free single-step synthesis of several crystalline metal monoborides containing earth-abundant transition metals. Rapid and exothermic self-propagating solid-state metathesis (SSM) reactions between metal halides and MgB2 form crystalline FeB, CoB, and NiB in seconds without sustained external heating and with high isolated product yields (∼80%). The metal borides are formed using a well-studied MgB2 precursor and compared to reactions using separate Mg and B reactants, which also produce self-propagating reactions and form crystalline metal borides. These SSM reactions are sufficiently exothermic to theoretically raise reaction temperatures to the boiling point of the MgCl2 byproduct (1412 °C). The chemically robust monoborides were examined for their ability to perform electrocatalytic water oxidation and reduction. Crystalline CoB and NiB embedded on carbon wax electrodes exhibit moderate and stable bifunctional electrocatalytic water splitting activity, while FeB only shows appreciable hydrogen evolution activity. Analysis of catalyst particles after extended electrocatalytic experiments shows that the bulk crystalline metal borides remain intact during electrochemical water-splitting reactions though surface oxygen species may impact electrocatalytic activity.

Polypyrrole supported Co–W–B nanoparticles as an efficient catalyst for improved hydrogen generation from hydrolysis of sodium borohydride

Effective and reusable catalysts with high performance are essentially necessary for NaBH 4 based on-demand hydrogen generators to the widespread use for energy conversion in fuel cell power systems. Herein, we report a facile synthesis of surfactant-directed polypyrrole-supported Co–W–B nanoparticles as a robust catalyst for efficient hydrolysis of NaBH 4 reaction. This non-noble metal catalyst provides much higher catalytic activity than a conventional cobalt boride catalyst. By incorporating tungsten to catalyst composition and tuning molar ratio of W/(Co + W), about a four-fold higher hydrogen generation rate was attained compared to bare Co–B. Among the all catalysts tested, Co–W–B/PPy with 7.5% W possessed the remarkable catalytic performance of 9.92 L min −1 g −1 and high stability over five cycles with the apparent activation energy of 49.18 kJ mol −1 . • Polypyrrole supported Co–W–B catalyst was prepared by reduction - precipitation route. • Hydrogen generation rate was highly improved by adding tungsten to the catalyst composition. • The catalyst with optimized composition showed the hydrogen generation rate of 9.92 L min −1 g −1 . • The catalyst was retained durability after five cycles.

Acid etching halloysite loaded cobalt boride material for supercapacitor electrode application

Inexpensive and eco-friendly cobalt boride@etched halloysite (CoB@eHal) composites with excellent electrochemical performances were fabricated by a facile combination of acid etching and chemical liquid-phase reduction. The highly conductive CoB nanoparticles were tightly combined with etched halloysite in a loaded manner. Owing to the open channels of etched halloysite after acid etching and the loading of intermetallic CoB, the CoB@eHal-12 composite exhibited a relatively large specific surface and low charge transfer resistance. The charge storage mechanism belonged to redox pseudocapacitance, and the contribution of pseudocapacitance in the whole charge storage process is 67.9%. The optimized CoB@eHal-12 demonstrated satisfactory specific capacitance of 266.9 F g−1 at 0.5 A g−1, outstanding rate capacity and unexceptionable cycling stability of approximately 84.7% retention over 10,000 continuous charge-discharge cycles. Furthermore, an asymmetric supercapacitor was constructed by using the CoB@eHal-12 as a cathode and activated carbon (AC) as an anode. The obtained CoB@eHal-12//AC device delivered a maximum energy density of 17.0 W h kg−1 with a power density of 200.2 W kg−1, and a satisfactory life cycle.

Electrochemically activated Co-Prussian blue analogue derived amorphous CoB nanostructures: an efficient electrocatalyst for the oxygen evolution reaction.

The oxygen evolution reaction is a kinetically sluggish half-cell reaction which plays an important role in tuning the efficiency of various electrochemical energy conversion systems. However, this process can be facilitated by manipulating the composition and morphology of the electrocatalyst. Here, by tuning the annealing temperature, a series of cobalt borides (CoB@300, CoB@450, CoB@550 and CoB@650) were synthesized from a metal-organic framework Prussian blue analogue (PBA) following boronization. The resulting borides were characterized systematically and we explored their electrocatalytic activity towards the oxygen evolution reaction (OER). In an alkaline electrolyte, the in situ surface transformation of the boride working electrode to the corresponding metaborite and cobalt oxyhydroxide took place which thereafter acted as the active catalytic sites for the OER. Interestingly, the amorphous form of cobalt boride (i.e., CoB@300) shows many fold increased catalytic activity compared to those of crystalline CoB and commercial RuO2 requiring only 290 mV overpotential to reach the benchmarked 10 mA cm-2 current density and the trend follows the order as CoB@300 > CoB@450 > CoB@550 > CoB@650 > PBA. The dominant catalytic activity of the amorphous cobalt boride nanostructure is attributed particularly to its amorphous nature and synergy between the in situ formed catalytically active centres (meta-borites and cobalt oxyhydroxide).