Showing papers on "Cobalt published in 2022"
124 citations
TL;DR: In this paper , a 2D Co-based MOF, Co3(C6H3NO2)2(cpna)2 (DMA)2]n (1) (H2cpna = 6-(4-carboxylphenyl)nicotinic acid; DMA = N,N-dimethylacetamide), has been synthesized and structurally characterized.
105 citations
TL;DR: NiCo 2 O 4 NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range, and showed higher degradation performance in actual wastewater as discussed by the authors .
Abstract: Developing an ultraefficient heterogeneous catalyst for peroxymonosulfate (PMS) activation at a wide pH range is a challenge. Herein, ultrathin NiCo 2 O 4 nanosheets (NiCo 2 O 4 NS, ~1 nm), with the dominant exposure of (311) facet, was designed for PMS activation. The NiCo 2 O 4 NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range. The synergistic effects between Ni and Co were the dominant activation mechanism. Compared with Co 3 O 4 , NiCo 2 O 4 NS adsorb PMS through a unique “bridge” mode, where both Co and adjacent Ni interact with the same O atom in PMS, increasing the number of electron transfer for enhanced breakage of O O bond. NiCo 2 O 4 NS with high cycling stability, could reach 100% degradation of other typical pollutants, and showed higher degradation performance in actual wastewater. This work unveils the intrinsic origin of the superior activity of Co-Ni spinel oxides for PMS activation for the first time, and demonstrates its application potential for organic contaminants degradation. • Ultrathin magnetic NiCo 2 O 4 nanosheet was synthesized by simple annealing hydroxides. • High PMS catalytic activity with 100% pollutant removal could be achieved. • The synergy between Co and Ni on highly active crystal (311) were realized. • Ni increases the Co-O covalency to favor Co-PMS adsorption and charge transfer. • Degradation pathway and intermediates’ ecotoxicity prediction were presented.
95 citations
TL;DR: In this article , a transitional bimetal-based carbon catalysts for oxygen reduction reaction (ORR) in alkaline fuel cells was proposed. But the performance of the proposed catalysts was not as good as commercial Pt/C (50 wt%) in a 0.1 M KOH solution, with a limiting current density as high as -5.54 mA cm-2.
88 citations
TL;DR: In this paper , a high-rate and robust quasi-solid-state Zn-air battery enabled by atomically dispersed cobalt sites anchored on wrinkled nitrogen doped graphene as the air cathode and a polyacrylamide organohydrogel electrolyte with its hydrogen-bond network modified by the addition of dimethyl sulfoxide was presented.
Abstract: Quasi-solid-state Zn-air batteries are usually limited to relatively low-rate ability (<10 mA cm-2), which is caused in part by sluggish oxygen electrocatalysis and unstable electrochemical interfaces. Here we present a high-rate and robust quasi-solid-state Zn-air battery enabled by atomically dispersed cobalt sites anchored on wrinkled nitrogen doped graphene as the air cathode and a polyacrylamide organohydrogel electrolyte with its hydrogen-bond network modified by the addition of dimethyl sulfoxide. This design enables a cycling current density of 100 mA cm-2 over 50 h at 25 °C. A low-temperature cycling stability of over 300 h (at 0.5 mA cm-2) with over 90% capacity retention at -60 °C and a broad temperature adaptability (-60 to 60 °C) are also demonstrated.
77 citations
TL;DR: In this article , a clicking confinement strategy is proposed to efficiently predisperse transition metal atoms in a precursor directed by click chemistry and ensure successful construction of abundant single-atom sites, where cobalt-coordinated porphyrin units are covalently clicked on the substrate for the confinement of the cobalt atoms and affording a CoN-C electrocatalyst.
Abstract: Rechargeable zinc-air batteries call for high-performance bifunctional oxygen electrocatalysts. Transition metal single-atom catalysts constitute a promising candidate considering their maximum atom efficiency and high intrinsic activity. However, the fabrication of atomically dispersed transition metal sites is highly challenging, creating a need for for new design strategies and synthesis methods. Here, a clicking confinement strategy is proposed to efficiently predisperse transitional metal atoms in a precursor directed by click chemistry and ensure successful construction of abundant single-atom sites. Concretely, cobalt-coordinated porphyrin units are covalently clicked on the substrate for the confinement of the cobalt atoms and affording a Co-N-C electrocatalyst. The Co-N-C electrocatalyst exhibits impressive bifunctional oxygen electrocatalytic performances with an activity indicator ΔE of 0.79 V. This work extends the approach to prepare transition metal single-atom sites for efficient bifunctional oxygen electrocatalysis and inspires the methodology on precise synthesis of catalytic materials.
75 citations
TL;DR: In this article , a single-atom catalyst featuring isolated Co anchored on nitrogen-doped carbon (Co-SAC/NC) via a highly efficient "plasma-bombing" strategy was proposed.
74 citations
TL;DR: In this paper , a ligand modulation strategy was proposed to boost the OER catalytic activity of cobalt-iron oxyhydroxide ((Fe,Co)OOH).
Abstract: Rationally designed catalysts hold the key to address the sluggish kinetics of oxygen evolution reaction (OER). However, engineering the active sites of such catalysts still faces grand challenges. This study proposes a feasible ligand modulation strategy to boost the OER catalytic activity of cobalt‐iron oxyhydroxide ((Fe,Co)OOH). The 2‐methylimidazole (MI) ligand coordination on (Fe,Co)OOH reduces the orbital overlap between the Fe/Co 3d and O 2p, which weakens the adsorption to oxygen‐containing intermediates and thus facilitates the unfavorable O2 desorption. As a result, the MI ligand modulated (Fe,Co)OOH achieves an excellent OER performance with low overpotentials (230/290 mV at 10/100 mA cm‐2) and excellent durability (>155 h). This study provides a novel ligand modulation strategy for the design of OER catalysts.
73 citations
TL;DR: In this paper , a secondary ion adsorption and defect-anchoring strategy was proposed to construct ultralight N-doped graphene aerogels containing isolated single cobalt atoms (Co-SAs/GAs).
Abstract: The widespread application of high-frequency electronic and communication devices has caused increasingly severe electromagnetic pollution. It is highly desirable but challenging to develop ultralight electromagnetic wave (EMW) absorbers with strong absorption performance to eliminate the negative effects of electromagnetic pollution. Herein, a secondary ion adsorption and defect-anchoring strategy was proposed to construct ultralight N-doped graphene aerogels containing isolated single cobalt atoms (Co-SAs/GAs) with a tunable content of Co-SAs from 1.13 to 2.58 wt. %. The optimal Co-SAs/GAs with a matching thickness of 1.5 mm and an ultralow filler ratio of 5 wt. % attenuated about 99.999% electromagnetic energy and exhibited specific EMW absorption performance (SMAP) of 37 220 dB cm2 g−1, which was 15 000 dB cm2 g−1 higher than that of the best reported absorber in literature. Permittivity and electrical conductivity measurements indicated that the introduction of Co-SAs significantly increased the conduction and polarization losses of the GAs, which was confirmed by simulation results based on the Havriliak–Negami equation. Theoretical calculations demonstrated that the Co–N4 moiety exhibited obvious polarization behavior, which could be further tuned by defective sites in its vicinity. This comprehensive investigation of the relationships between single-atom structure and electromagnetic wave absorption property provides an efficient route toward the rational design of ultralight absorbers with metal single-atoms.
72 citations
05 May 2022
TL;DR: In this article , the authors isolated cobalt atoms with dual nitrogen and oxygen coordination (Co-N 3 O 1 ) on oxygen-doped tubular carbon nitride (TCN) by pyrolyzing a hydrogen-bonded cyanuric acid melamine-cobalt acetate precursor.
Abstract: Simultaneous regulation of the coordination environment of single-atom catalysts and engineering architectures with efficient exposed active sites are efficient strategies for boosting peroxymonosulfate (PMS) activation. We isolated cobalt atoms with dual nitrogen and oxygen coordination (Co-N 3 O 1 ) on oxygen-doped tubular carbon nitride (TCN) by pyrolyzing a hydrogen-bonded cyanuric acid melamine-cobalt acetate precursor. The theoretically constructed Co-N 3 O 1 moiety on TCN exhibited an impressive mass activity of 7.61×105 min -1 mol -1 with high 1 O 2 selectivity. Theoretical calculations revealed that the cobalt single atoms occupied a dual nitrogen and oxygen coordination environment, and that PMS adsorption was promoted and energy barriers reduced for the key *O intermediate that produced 1 O 2 . The catalysts were attached to a widely used poly(vinylidene fluoride) microfiltration membrane to deliver an antibiotic wastewater treatment system with 97.5% ciprofloxacin rejection over 10 hours, thereby revealing the suitability of the membrane for industrial applications.
70 citations
TL;DR: In this article , the fabrication of multi-cation incorporated Fe 2+/3+ /Co 2+ species into selenides nanorods (Fe@Co/Se 2 -NRs) and corresponding analysis of their catalytic activity for electrochemical and solar-driven water splitting as a purpose of the composition are reported.
Abstract: Water-electrolysis intends a favorable green technology to hold the worldwide energy and ecological disaster, but its efficacy is significantly restricted by the slow reaction kinetics of both the anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). Herein, the fabrication of multi-cation incorporated Fe 2+/3+ /Co 2+ species into selenides nanorods (Fe@Co/Se 2 -NRs) and corresponding analysis of their catalytic activity for electrochemical (EC) and solar-driven water splitting as a purpose of the composition are reported. This efficient approach can fabulously endow electronic structure modulation and the direct evidence of electron-transfer-route between transition-metals and selenides, which are vital to improving the electrocatalytic activity, has never been confirmed before. For the first time, we explored the electron-transfer route of intensely-coupled Fe@Co/Se 2 -NRs catalyst, in which the Fe 2+/3+ /Co 2+ species strongly-coupled to selenide through the Fe-coordinated Co-bridged-bond. Finally, density functional theory calculations disclose that the multi-cation doping effects into selenides are vital for enhanced electrocatalytic performance. • The self-templated approach developed for bifunctional OER/HER electrocatalysts. • Iron-Cation-Coordinated Cobalt-Bridged-Selenides Nanorods structure increases the number of active sites. • The Fe@Co/Se 2 -nanorods reveal superior bifunctional OER/HER performance. • Requires only 1.5 V@10 mA cm −2 for electrochemical and solar-to-hydrogen conversion efficacy of ∼ 7.0% for water splitting. • DFT and XAS analysis exposed the electron-transfer route of intensely coupled Fe@Co/Se 2 -NRs.
TL;DR: In this paper , an effective plasma engineering strategy to construct Fe/Co dual single atoms densely dispersed on porous nitrogen-doped carbon nanofibers (Fe, Co SAs-PNCF) with a high mass loading of 9.8 wt% is proposed without any acid leaching.
TL;DR: In this article , an anion-doping-induced vacancy engineering is pioneered, where the selective oxidation process upgrades the transformation from Co-based precursor to S−doped CoSe2 (System II) instead of Se−doping CoS2 (system I) in the subsequent sulfuration/selenization, which results in vacancy level improvement and coexistence of sulfur vacancies (VS) and selenium vacancy (VSe).
Abstract: Vacancy engineering is an attractive approach to modulate the electronic structure of transition metal chalcogens. However, illustrating how anion vacancy can be engineered to tailor their electromagnetic (EM) parameters and electromagnetic wave (EMW) absorption, based on clear vacancy concentrations and/or various anion vacancies rather than semiempirical rules, is currently lacking but significantly desired. An anion‐doping‐induced vacancy engineering is pioneered, where the selective oxidation process upgrades the transformation from Co‐based precursor to S‐doped CoSe2 (System II) instead of Se‐doped CoS2 (System I) in the subsequent sulfuration/selenization, which results in vacancy level improvement and coexistence of sulfur vacancies (VS) and selenium vacancy (VSe). Thanks to the boosted dielectric polarization loss provided by the comparable coexistence of sulfur/selenium vacancies (VS/VSe = 0.52), S‐doped CoSe2 harvests a broad bandwidth of 9.25 GHz (8.75–18.00 GHz) at 2.42 mm. This feature almost simultaneously achieves 100% coverage for X‐, and Ku‐bands, outperforming all reported metal sulfides/selenides until now. This work establishes a clear correlation between vacancy concentrations/various anion vacancies and EMW dissipation ability, offering valuable insights for designing advanced EMW absorbing materials.
TL;DR: In this article , a simulation of historical (1998-2019) and future (2020-2050) global cobalt cycles covering both traditional and emerging end uses with regional resolution (China, the U.S., Japan, the EU, and the rest of the world) is presented.
Abstract: In recent years, increasing attention has been given to the potential supply risks of critical battery materials, such as cobalt, for electric mobility transitions. While battery technology and recycling advancement are two widely acknowledged strategies for addressing such supply risks, the extent to which they will relieve global and regional cobalt demand-supply imbalance remains poorly understood. Here, we address this gap by simulating historical (1998-2019) and future (2020-2050) global cobalt cycles covering both traditional and emerging end uses with regional resolution (China, the U.S., Japan, the EU, and the rest of the world). We show that cobalt-free batteries and recycling progress can indeed significantly alleviate long-term cobalt supply risks. However, the cobalt supply shortage appears inevitable in the short- to medium-term (during 2028-2033), even under the most technologically optimistic scenario. Our results reveal varying cobalt supply security levels by region and indicate the urgency of boosting primary cobalt supply to ensure global e-mobility ambitions.
TL;DR: In this paper , a closed-loop recycling strategy was proposed starting from spent Li-ion battery cathode materials to high-performance cathodes with less energy consumption and little pollution, which exhibits excellent economic and environmental benefits.
01 May 2022
TL;DR: In this paper , a hybridization of three bimetallic phosphides, nickel-molybdenum (Ni-Mo), cobalt-naphase (CoMo), and cobaltnickel (CoNi), in single ultrathin-3D-nanosheets on nickel foam was carried out to fabricate an active and robust trimetallic metal-phosphide electrocatalyst for overall electrochemical water splitting.
Abstract: Highly efficient electrocatalysts based on non-noble and earth-abundant elements for overall water splitting are of great significance for sustainable energy conversion and storage. Herein, hybridization of three bimetallic phosphides, nickel-molybdenum (Ni–Mo), cobalt-molybdenum (Co–Mo), and cobalt-nickel (Co–Ni), in single ultrathin-3D-nanosheets on nickel foam ([email protected]) was carried out to fabricate an active and robust trimetallic metal-phosphide electrocatalyst for overall electrochemical water splitting. Simple hydrothermal synthesis followed by chemical vapor deposition-based phosphorization was used to fabricate the present catalyst. By using the optimum stoichiometric ratios of metals precursors, [email protected] nanosheets were achieved with the best electrical conductivity and high electrochemically active sites, resulting in high electrocatalytic activities with excellent kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The [email protected] exhibited a low overpotential of 88 mV at 10 mA cm−2 for HER and a low overpotential of 250 mV at 10 mA cm−2 for OER. The [email protected] (+, -) device required a cell voltage of 1.52 V to reach a current density of 10 mA cm−2 in an alkaline electrolytic solution. The present study demonstrated that [email protected] as the best transition metal phosphide for overall water splitting.
TL;DR: In this article, the effect of concentration variation of reactants (nickel and cobalt ratio) in nickel cobalt phosphate material and their influence on physicochemical properties and electrochemical capacitive performances are investigated.
TL;DR: In this article , the authors proposed the NO3-RR (nitrate reduction reaction, NO 3-RR) under ambient conditions, which overcomes the drawbacks of energy-intensive Haber−Bosch reaction and low-efficient N2 electroreduction.
Abstract: Electrochemical reduction of nitrate to ammonia (nitrate reduction reaction, NO3-RR) under ambient conditions, which overcomes the drawbacks of energy-intensive Haber−Bosch reaction and low-efficient N2 electroreduction, is one of the alternatives...
TL;DR: In this article , a direct repairing method for degraded LiCoO2 using a LiCl-CH4N2O deep eutectic solvent (DES) was established.
Abstract: Abstract Traditional recycling processes of LiCoO2 rely on destructive decomposition, requiring high-temperature roasting or acid leaching to extract valuable Li and Co, which have significant environmental and economic concerns. Herein, a direct repairing method for degraded LiCoO2 using a LiCl–CH4N2O deep eutectic solvent (DES) was established. The DES is not used to dissolve LiCoO2 but directly serves as a carrier for the selective replenishment of lithium and cobalt. Replenishment of lithium restores LiCoO2 at different states of charge to a capacity of 130 mAh/g (at 0.1 C rate), while replenishing the cobalt increases the capacity retention rate of 90% after 100 cycles, which is comparable to pristine LiCoO2. The DES is collected and reused multiple times with a high repair efficiency. This process reduces energy consumption by 37.1% and greenhouse gas emissions by 34.8% compared with the current production process of LiCoO2, demonstrating excellent environmental and economic viability.
TL;DR: By adopting a precursor modulation strategy, the authors successfully synthesize single cobalt atom catalysts embedded in nitrogen-doped carbon, Co-N/C, with similar overall Co and N concentrations but different N types, that is, pyridinic N (NP ), graphitic N (NG ), and pyrrolic N ( NPY ).
Abstract: Nonprecious group metal (NPGM)-based single atom catalysts (SACs) hold a great potential in electrocatalysis and dopant engineering has been extensively exploited to boost their catalytic activity, while the coordination environment of dopant, which also significantly affects the electronic structure of SACs, and consequently their electrocatalytic performance, have been largely ignored. Here, by adopting a precursor modulation strategy, the authors successfully synthesize single cobalt atom catalysts embedded in nitrogen-doped carbon, Co-N/C, with similar overall Co and N concentrations but different N types, that is, pyridinic N (NP ), graphitic N (NG ), and pyrrolic N (NPY ). Co-N/C with the Co-N4 moieties coordinated with NG displays far superior activity for oxygen reduction (ORR) and evolution reactions, and superior activity and stability in both zinc-air batteries and proton exchange membrane fuel cells. Density functional theory calculation indicates that coordinated N species in particular NG functions as electron donors to the Co core of Co-N4 active sites, leading to the downshift of d-band center of Co-N4 and weakening the binding energies of the intermediates on Co-N4 sites, thus, significantly promoting catalytic kinetics and thermodynamics for ORR in a full pH range condition.
TL;DR: In this paper , a unique nanostructure microwave absorber with ultrasmall magnetic particles was prepared, which achieved a minimum reflection loss of −41.08 dB with a thickness of 2 mm and effective absorption bandwidth (EAB) of 4.26 GHz.
TL;DR: Cobalt ferrite (CoFe 2 O 4 , CF) nanoparticles were anchored on the multiwalled carbon nanotube (MWCNT) for synthesis of CF@MWCnt nanocomposite and enhancing the catalytic activity of CF as discussed by the authors .
TL;DR: In this article, a photo-activation peroxymonosulfate (PMS) was applied as a catalyst for degradation of bisphenol A (BPA) based on identified intermediates, a possible degradation pathway was proposed for BPA.
TL;DR: In this paper , a self-templated strategy was applied to introduce hierarchically nanostructured all-surface cobalt phosphide nanoboxes (Co@CoFe-P NBs) for industrial-scale applications.
Abstract: The rational design of efficient electrocatalysts for industrial water splitting is essential to generate sustainable hydrogen fuel. However, a comprehensive understanding of the complex catalytic mechanisms under harsh reaction conditions remains a major challenge. We apply a self-templated strategy to introduce hierarchically nanostructured “all-surface” Fe-doped cobalt phosphide nanoboxes (Co@CoFe–P NBs) as alternative electrocatalysts for industrial-scale applications. Operando Raman spectroscopy and X-ray absorption spectroscopy (XAS) experiments were carried out to track the dynamics of their structural reconstruction and the real catalytically active intermediates during water splitting. Our operando analyses reveal that partial Fe substitution in cobalt phosphides promotes a structural reconstruction into P–Co–O–Fe–P configurations with low-valence metal centers (M0/M+) during the hydrogen evolution reaction (HER). Results from density functional theory (DFT) demonstrate that these in situ reconstructed configurations significantly enhance the HER performance by lowering the energy barrier for water dissociation and by facilitating the adsorption/desorption of HER intermediates (H*). The competitive activity in the oxygen evolution reaction (OER) arises from the transformation of the reconstructed P–Co–O–Fe–P configurations into oxygen-bridged, high-valence CoIV–O–FeIV moieties as true active intermediates. In sharp contrast, the formation of such CoIII/IV–O–FeIII/IV moieties in Co–FeOOH is hindered under the same conditions, which outlines the key advantages of phosphide-based electrocatalysts. Ex situ studies of the as-synthesized reference cobalt sulfides (Co–S), Fe doped cobalt selenides (Co@CoFe–Se), and Fe doped cobalt tellurides (Co@CoFe–Te) further corroborate the observed structural transformations. These insights are vital to systematically exploit the intrinsic catalytic mechanisms of non-oxide, low-cost, and robust overall water splitting electrocatalysts for future energy conversion and storage.
TL;DR: In this article, a cobalt-iron nitride/alloy nanosheets on nickel foam (CoFe-NA/NF) was constructed as a bifunctional catalyst for both hydrogen evolution reaction and oxygen evolution reaction (OER).
TL;DR: In this paper , the authors introduced nitrogen (N) vacancies into graphite carbon nitride imbedded with cobalt carbonate (CCH/CN-Vn) in a peroxymonosulfate (PMS)/visible light system to break the limitations of a conventional two-electron transfer path.
Abstract: Rapid generation of high-valent cobalt-oxo species (Co(IV)═O) for the removal of organic contaminants has been challenging because of the low conversion efficiency of Co(III)/Co(II) and the high activation energy barrier of the Co(II)-oxidant complex. Herein, we introduced nitrogen (N) vacancies into graphite carbon nitride imbedded with cobalt carbonate (CCH/CN-Vn) in a peroxymonosulfate (PMS)/visible light system to break the limitations of a conventional two-electron transfer path. These N vacancies enhanced the electron distribution of the Co 3d orbital and lowered the energy barrier to cleave the O-O bond of PMS in the Co(II)-PMS complex, achieving the modulation of major active species from 1O2 to Co(IV)═O. The developed synergistic system that exhibited adsorption and oxidation showed remarkable selectivity and contaminant removal performance in inorganic (Cl-, NO3-, HCO3-, and HPO4-) organic (HA) and even practical aqueous matrices (tap water and secondary effluent). This study provides a novel mechanistic perspective to modulate the nonradical path for refractory contaminant treatment via defect engineering.
TL;DR: In this paper , a solvent-free method to synthesize Co-MOF and its derivatives was proposed, which bridged the cobalt (II) ion of CoSnO3 and the 2-methylimidazole skeleton.