Search Results (77)

In the wake of global energy transition and the “dual-carbon” goal, the rapid growth of electric vehicles has posed challenges for large-scale lithium-ion battery decommissioning. Retired batteries exhibit dual attributes of strategic resources (cobalt/lithium concentrations several times higher than natural ores) and environmental risks (heavy metal pollution, electrolyte toxicity). This paper systematically reviews pyrometallurgical and hydrometallurgical recovery technologies, identifying bottlenecks: high energy/lithium loss in pyrometallurgy, and corrosion/cost/solvent regeneration issues in hydrometallurgy. To address these, an integrated recycling process is proposed: low-temperature physical separation (liquid nitrogen embrittlement grinding + froth flotation) for cathode–anode separation, mild roasting to convert lithium into water-soluble compounds for efficient metal oxide separation, stepwise alkaline precipitation for high-purity lithium salts, and co-precipitation synthesis of spherical hydroxide precursors followed by segmented sintering to regenerate LiNi_1/3Co_1/3Mn_1/3O₂ cathodes with morphology/electrochemical performance comparable to virgin materials. This low-temperature, precision-controlled methodology effectively addresses the energy-intensive, pollutive, and inefficient limitations inherent in conventional recycling processes. By offering an engineered solution for sustainable large-scale recycling and high-value regeneration of spent ternary lithium ion batteries (LIBs), this approach proves pivotal in advancing circular economy development within the renewable energy sector. Full article

The efficient mass transport and enhanced accessibility of active sites are crucial for high-performance electrocatalysts in water splitting. Inspired by the hierarchical structure of natural wood, we engineered a monolithic electrocatalyst, cobalt nanoparticles encapsulated in nitrogen-doped carbon layers on carbonized wood (Co@NC/CW), by carbonizing wood to create a three-dimensional framework with vertically aligned macropores. The unique architecture encapsulates cobalt nanoparticles within in situ-grown nitrogen-doped graphene layers on wood-derived microchannels, facilitating ultrafast electrolyte infusion and anisotropic electron transport. As a result, the optimized freestanding Co@NC/CW electrode exhibits remarkable bifunctional activity, achieving overpotentials of 403 mV and 227 mV for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, at a current density of 50 mA cm⁻². Furthermore, the integrated hybrid electrolyzer combining the HER and the OER delivers an impressive 50 A cm⁻² at a cell voltage of 1.72 V while maintaining a Faradaic efficiency near 99.5% and sustaining long-term stability over 120 h of continuous operation. Co@NC/CW also demonstrates performance in the complete decomposition of alkaline seawater, underscoring its potential for scalable applications. This wood-derived catalyst design not only leverages the natural hierarchical porosity of wood but also offers a sustainable platform for advanced electrochemical systems. Full article

The development of efficient, sustainable, and cost-effective catalysts is crucial for energy storage technologies, such as zinc–air batteries (ZABs). These batteries require bifunctional catalysts capable of efficiently and selectively catalyzing oxygen redox reactions. However, the high cost and low selectivity of conventional catalysts hinder the large-scale integration of ZABs into the electric grid. This study presents binder-free Fe-based bifunctional electrocatalysts synthesized via a sol–gel method, followed by thermal treatment under ammonia flow. Supported on nickel foam, the catalyst exhibits enhanced activity for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), essential for ZAB operation. This work addresses two critical challenges in the development of ZABs: first, the replacement of costly cobalt or platinum-group-metal (PGM)-based catalysts with an efficient alternative; second, the achievement of prolonged battery performance under real conditions without passivation. Structural analysis confirms the integration of iron nitrides, oxides, and carbon, resulting in high conductivity and catalytic stability without relying on precious or cobalt-based metals. Electrochemical tests reveal that the catalyst calcined at 800 °C delivers superior performance, achieving a four-electron ORR mechanism and prolonged operational life compared to its 900 °C counterpart. Both catalysts outperform conventional Pt/C-RuO₂ systems in stability and selective bifunctionality, offering a more sustainable and cost-effective alternative. The innovative combination of nitrogen, carbon, and iron compounds overcomes limitations associated with traditional materials, paving the way for scalable, high-performance applications in renewable energy storage. This work underscores the potential of transition metal-based catalysts in advancing the commercial viability of ZABs. Full article

Developing non-noble metal catalysts that exhibit oxygen reduction reaction (ORR) activity comparable to or exceeding that of platinum-based catalysts remains a significant challenge. This research presents the successful fabrication of novel cobalt-nitrogen (Co-N) catalysts through a straightforward one-step synthesis method. This method involves stirring a mixture of cobalt (II) nitrate, polyhexamethylene guanidine (PHMG) as a nitrogen source, and carbon spheres at ambient temperature. By varying the mass ratio of PHMG to cobalt salt, three distinct catalyst formulations were produced. The catalyst with an optimal PHMG-to-cobalt nitrate ratio of 2:1 (Co-PHMG-2@C) exhibited exceptional electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline electrolytes. This catalyst demonstrated a high onset potential of 0.97 V and a half-wave potential of 0.82 V versus the reversible hydrogen electrode (RHE), favorably comparable to those of the benchmark Pt/C catalyst (1.02 V vs. RHE). Furthermore, Co-PHMG-2@C displayed superior stability and resistance to methanol poisoning. The scalability of this synthesis technique offers a promising pathway for cost-effective and environmentally friendly production of carbon nanomaterials for applications in fuel cells and other electrochemical energy devices. Full article

The development of sustainable and high-performance oxygen reduction reaction (ORR) electrocatalysts is fundamental to fuel cell implementation. Non-precious transition metal oxides present interesting electrocatalytic behavior, and their incorporation into N-doped carbon supports leads to excellent ORR performance. Herein, we prepared a shrimp shell-derived biochar (CC), which was doped with nitrogen via a ball milling approach (N-CC), and then used as support for Co₃O₄ nanoparticles growth (N-CC@Co₃O₄). Co₃O₄ loading was optimized using three different amounts of cobalt precursor: 1.56, 2.33 and 3.11 mmol in N-CC@Co₃O₄_1, N-CC@Co₃O₄_2 and N-CC@Co₃O₄_3, respectively. Interestingly, all prepared electrocatalysts, including the initial biochar CC, presented electrocatalytic activity towards ORR. Both N-doping and the introduction of Co₃O₄ NPs had a significant positive effect on ORR performance. Meanwhile, the three composites showed distinct ORR behavior, demonstrating that it is possible to tune their electrocatalytic performance by changing the Co₃O₄ loading. Overall, N-CC@Co₃O₄_2 achieved the most promising ORR results, displaying an E_onset of 0.84 V vs. RHE, j_L of −3.45 mA cm⁻² and excellent selectivity for the 4-electron reduction (n = 3.50), besides good long-term stability. These results were explained by a combination of high content of pyridinic-N and graphitic-N, high ratio of pyridinic-N/graphitic-N, and optimized Co₃O₄ loading interacting synergistically with the porous N-CC support. Full article

Developing low-cost, efficient alternatives to catalysts for bifunctional oxygen electrode catalysis in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for advancing the practical applications of alkaline fuel cells. In this study, Co particles and single atoms co-loaded on nitrogen-doped carbon (CoNC) were synthesized via pyrolysis of a C₃N₄ and cobalt nitrate mixture at varying temperatures (900, 950, and 1000 °C). The pyrolysis temperature and precursor ratios were found to significantly influence the ORR/OER performance of the resulting catalysts. The optimized CoNC-950 catalyst demonstrated exceptional ORR (E_1/2 = 0.85 V) and OER (E_j10 = 320 mV) activities, surpassing commercial Pt/C + RuO₂-based devices when used in a rechargeable zinc–air battery. This work presents an effective strategy for designing high-performance non-precious metal bifunctional electrocatalysts for alkaline environments. Full article

The oxygen reduction reaction (ORR) plays a central role in energy conversion and storage technologies. A promising alternative to precious metal catalysts are non-precious metal doped carbons. Considerable efforts have been devoted to cobalt-doped carbonized polyacrylonitrile catalysts, but the optimization of their catalytic performance remains a key challenge. We have proposed a multifunctional active metal source strategy based on the cobalt complex with the ligand containing pyridine and azo-fragments. This complex simultaneously provides the nitrogenous environment for the Co atoms and acts as a blowing agent due to N₂ extrusion, thus increasing the surface area and porosity of the material. This strategy provided the catalysts with a high surface area and pore volume, combined with the greater fraction of Co-N clusters, and a lesser amount and smaller size of Co metal particles compared to conventionally prepared catalysts, resulting in improved catalytic performance. In addition to strict 4-electron ORR kinetics and 383 mV overpotential, the novel catalysts exhibit limiting current values close to the Pt/C benchmark and greatly overcome the Pt in methanol tolerance. These results demonstrate the critical role of metal source structure and carbonization parameters in tailoring the structural and electrochemical properties of the catalysts. Full article

Electrocatalytic nitrate reduction enables the recovery of nitrate from water under mild conditions and generates ammonia for nitrogen fertilizer feedstock in an economical and green means. In this paper, Co/biomass carbon (Co/BC) composite catalysts were prepared by co-carbonization of straw and metal–organic framework material ZIF-67 for electrocatalytic nitrate reduction using hydrothermal and annealing methods. The metal–organic framework structure disperses the catalyst components well and provides a wider specific surface area, which is conducive to the adsorption of nitrate and the provision of more reactive active sites. The introduction of biomass carbon additionally enhances the electrical conductivity of the catalyst and facilitates electron transport. After electrochemical testing, Co/BC-100 exhibited the best performance in electrocatalytic nitrate reduction to ammonia, with an ammonia yield of 3588.92 mmol g_cat.⁻¹ h⁻¹ and faradaic efficiency of 97.01% at −0.5 V vs. RHE potential. This study provides a promising approach for the construction of other efficient cobalt-based electrocatalysts. Full article

Designing efficient electrode materials is necessary for supercapacitors but remains highly challenging. Herein, cobalt sulfide with crystalline/amorphous heterophase (denoted as Co(Al)S) derived from an Al metal–organic framework was constructed by ion exchange/acid etching and subsequent sulfidation strategy. It was found that rational sulfidation by adjusting the sulfur source concentration to a suitable level was favorable to form a 3D nanosheet-interconnected network architecture with a large specific surface area, which promoted ion/electron transport and charge separation. Benefiting from the features of the unique network structure and heterophase accompanied by aluminum, nitrogen and carbon coordinated in amorphous phase, the optimal Co(Al)S₍₁₀₎ exhibited a high specific capacity (1791.8 C g⁻¹ at 1 A g⁻¹), an outstanding rate capability and an excellent cycling stability. Furthermore, the as-assembled Co(Al)S//AC device afforded an energy density of 72.3 Wh kg⁻¹ at a power density of 750 W kg⁻¹, verifying that the Co(Al)S was a promising material for energy storage devices. The developed scheme is expected to promote the application of MOF-derived electrode materials in electrochemical energy storage and conversion fields. Full article

This study presents a promising method for creating high-performance supercapacitor electrodes. The approach involves crafting a unique composite material—nickel-cobalt-layered double hydroxides (NiCo-LDH) grown on carbon nanoballs (CNBs). This is achieved by first creating a special carbon material rich in oxygen and nitrogen from a polybenzoxazine source. At first, eugenol, ethylene diamine and paraformaldehyde undergo Mannich condensation to form the benzoxazine monomer, which undergoes self-polymerization in the presence of heat to produce polybenzoxazine. This was then carbonized and activated to produce CNBs containing heteroatoms. Then, through a hydrothermal technique, NiCo-LDH nanocages are directly deposited onto the CNBs, eliminating the need for complicated templates. The amount of CNBs used plays a crucial role in performance. By optimizing the CNB content to 50%, a remarkable specific capacitance of 1220 F g⁻¹ was achieved, along with excellent rate capability and impressive cycling stability, retaining 86% of its capacitance after 5000 cycles. Furthermore, this NiCo-LDH/CNB composite, when combined with active carbon in a supercapacitor configuration, delivered outstanding overall performance. The exceptional properties of this composite, combined with its simple and scalable synthesis process, position it as a strong contender for next-generation sustainable energy storage devices. The ease of fabrication also opens doors for its practical application in advancing energy storage technologies. Full article

Lignin, which contains aromatic phenols, is the second most abundant renewable biomass material in the world. It is the main byproduct of the paper industry and is characterized by abundant sources, renewability, and low cost. The present study focused on the extraction of lignin from poplar wood through a straightforward papermaking approach, thereafter utilizing the resultant black liquor containing lignin for synthesizing lignin-based phenolic resins. During the polymerization process, cobalt (Co) and nickel (Ni) species were introduced and, subsequently, a CoNi/biochar catalyst was obtained through pyrolysis in a nitrogen atmosphere. The prepared catalyst possessed rough spherical structures. The incorporation of Co and Ni enhanced charge redistribution, thereby imparting the catalyst with strong electron acceptance capabilities. The prepared lignin-based phenolic-resin-derived carbon was used for the electrochemical sensing of 2-nitrophenol. The limit of detection (LOD) for 2-nitrophenol was calculated to be 0.0132 µM, with good repeatability, stability, and selectivity. Full article

Chromium- and cobalt-based alloys, as well as chrome–nickel steels, are most used in dental prosthetics. Unfortunately, these alloys, especially nickel-based alloys, can cause allergic reactions. A disadvantage of these alloys is also insufficient corrosion resistance. To improve the properties of these alloys, amorphous Si (C,N) coatings were deposited on the surfaces of metal specimens. This paper characterizes coatings of silicon carbide nitrides, deposited by the magnetron sputtering method on the surface of nickel–chromium alloys used in dental prosthetics. Depending on the deposition parameters, coatings with varying carbon to nitrogen ratios were obtained. The study analyzed their structure and chemical and phase composition. In addition, a study of surface wettability and surface roughness was performed. Based on the results obtained, it was found that amorphous coatings of Si (C,N) type with thicknesses of 2 to 4.5 µm were obtained. All obtained coatings increase the value of surface free energy. The study showed that Si (C,N)-type films can be used in dental prosthetics as protective coatings. Full article

The conversion of furfural to furfuryl alcohol is one of the most significant reactions from industrial-scale produced biomass platform molecules to value-added chemicals. In this work, biomass-based chitosan was used as both a carbon source and nitrogen source to synthesize nitrogen-doped carbon. With the addition of cobalt, the optimized 7.5Co-NC-900 catalyst had the largest surface area and the graphite nanotube structure with the least defects. It was employed for the hydrogenation of furfural to furfuryl alcohol and reached a nearly full conversion and an equivalent yield at 130 °C in 4 MPa initial H₂. The structure–function relationship study indicated that the N could interact with the neighbor Co in this catalyst and formed an electron-deficient Co center which was in favor of the adsorption of furfural in the nanotube and had high catalytic activity. The interactions between Co and N stabilized the catalyst so that it could remain stable in five runs of catalytic reactions. Full article

Cobalt–nitrogen co-doped carbon nanotubes (Co3@NCNT-800) were synthesized via a facile and economical approach to investigate the efficient degradation of organic pollutants in aqueous environments. This material demonstrated high catalytic efficiency in the degradation of carbamazepine (CBZ) in the presence of peroxymonosulfate (PMS). The experimental data revealed that at a neutral pH of 7 and an initial CBZ concentration of 20 mg/L, the application of Co3@NCNT-800 at 0.2 g/L facilitated a degradation rate of 64.7% within 60 min. Mechanistic investigations indicated that the presence of pyridinic nitrogen and cobalt species enhanced the generation of reactive oxygen species. Radical scavenging assays and electron spin resonance spectroscopy confirmed that radical and nonradical pathways contributed to CBZ degradation, with the nonradical mechanism being predominant. This research presents the development of a novel PMS catalyst, synthesized through an efficient and stable method, which provides a cost-effective solution for the remediation of organic contaminants in water. Full article

The oxidation of aqueous solutions containing Allura Red AC (AR–AC) using bicarbonate-activated peroxide (BAP) and cobalt-impregnated pillared clay (Co/Al–PILC) as the catalyst was investigated. Using the CCD-RMS approach (central composite design–response surface methodology), the effects of dye, H₂O₂, and NaHCO₃ concentrations on AR–AC degradation were studied. The decolorization, total nitrogen (TN), and total carbon (TC) removals were the analyzed responses, and the experimental data were fitted to empirical quadratic equations for these responses, obtaining coefficients of determination R² and adjusted-R² higher than 0.9528. The multi-objective optimization conditions were [dye] = 21.25 mg/L, [H₂O₂] = 2.59 mM, [NaHCO₃] = 1.25 mM, and a catalyst loading of 2 g/L. Under these conditions, a decolorization greater than 99.43% was obtained, as well as TN and TC removals of 72.82 and 18.74%, respectively, with the added advantage of showing cobalt leaching below 0.01 mg/L. Chromatographic analyses (GC–MS and HPLC) were used to identify some reaction intermediates and by-products. This research showed that wastewater containing azo dyes may be treated using the cobalt-catalyzed BAP system in heterogeneous media. Full article