Search Results (19)

Cobalt-doped iron disulfide (FeS₂) thin films were synthesized via chemical bath deposition (CBD) followed by annealing at 450 °C, yielding phase-pure pyrite structures with multifunctional properties. A deposition temperature of 95 °C is critical for promoting Co incorporation, suppressing sulphur vacancies, and achieving structural stabilization of the film. After annealing, the dendritic morphologies transformed into compact quasi-spherical nanoparticles (~100 nm), which enhanced the crystallinity and optoelectronic performance of the films. The films exhibited strong absorption (>50%) in the visible and near-infrared regions and tunable direct bandgaps (1.14 to 0.96 eV, within the optimal range for single-junction solar cells. Electrical characterization revealed a fourth-order increase in conductivity after annealing (up to 4.78 Ω⁻¹ cm⁻¹) and confirmed stable p-type behavior associated with Co²⁺-induced acceptor states and defect passivation. These results demonstrate that CBD enabled the fabrication of Co-doped FeS₂ thin films with synergistic structural, electrical, and optical properties. The integration of earth-abundant elements and tunable electronic properties makes these films promising absorber materials for the next-generation photovoltaic devices. Full article

Cobalt–molybdenum $\eta$-carbides are attractive hydrodesulfurization (HDS) catalysts, yet controlling their phase composition and nanostructure remains challenging. Here, a ${\mathrm{Co}}_{25}{\mathrm{Mo}}_{25}{\mathrm{C}}_{50}$ powder was prepared by mechanical alloying in a horizontal mill, with and without superimposed vertical vibration. Phase composition was determined by X-ray diffraction using the reference-intensity-ratio method, and the nanostructure was examined by SEM and HRTEM. Aquathermolysis of a heavy crude was monitored by ATR-FTIR in the window characteristic of S–S and C–S vibrations. Both milling routes produced the $\eta$-carbides ${\mathrm{Co}}_3{\mathrm{Mo}}_3$C and ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C, as well as ${\mathrm{Co}}_2{\mathrm{Mo}}_3$, ${\mathrm{Co}}_7{\mathrm{Mo}}_6$, and ${\mathrm{Co}}_3$C; vibration-assisted milling increased the ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C fraction and generated thin lamellae exhibiting Moiré contrast. In FTIR, the ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C-rich powder showed strong attenuation of the disulfide and thioether bands, whereas the ${\mathrm{Co}}_3{\mathrm{Mo}}_3$C-rich powder behaved similarly to the water-only baseline under mild conditions (100 °C, 4 h). These results indicate that mechanical alloying with superposed vibration enables control over phase and nanostructure, and that a higher ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C fraction correlates with a stronger HDS response under aquathermolysis. The approach offers a scalable route to Co–Mo carbides that are active for desulfurization at 100 °C in water without added ${\mathrm{H}}_2$. Full article

Bioplastics are adopted to replace fossil-based plastics because they are microplastic-free and self-degradable without releasing greenhouse gasses. Despite having many benefits, the main applications of bioplastics are packaging and kitchenware. Moreover, the utilization of bioplastics in electronic applications is still underexplored. Consequently, the development of bioplastics for electronic applications, especially heterojunctions, is essential. Here, we report a novel molybdenum disulfide (MoS₂)/cobalt oxide (Co₃O₄) heterojunction based on bioplastic semiconductors, with agar as a matrix. This work also exposes the effect of carrier concentration on the mechanism of an energy band. Using the density of state in three dimensions, Anderson’s rule, and the Fermi energy level calculated by carrier concentration, we find that the energy gaps of the MoS₂/Co₃O₄ heterojunction at various concentrations almost match the energy gap evaluated by Tauc’s relation. Additionally, leveraging the MoS₂/Co₃O₄ heterojunction as a photodetector, the optimized device indicates an ideality factor of 1.59, a response time of 127 ms, and a recovery time of 115 ms. Our work not only represents a significant step towards using bioplastics in electronic applications but also reveals the mechanism of the energy band affected by carrier concentration. Full article

The development of metal sulfides as anodes for sodium-ion batteries (SIBs) is significantly obstructed by the slow kinetics of the electrochemical reactions and the substantial volume changes on the cycling. Herein, we introduce a selenium-substituted cobalt disulfide embedded within a dual carbon–graphene framework (Se-CoS₂/C@rGO) for high-performance SIBs. The Se-CoS₂/C@rGO was prepared via a synchronous sulfurization/selenization strategy using Co-alkoxide as the precursor and SeS₂ as the source of selenium and sulfur, during which the EG anions are converted in situ to a S, Se codoped carbon scaffold. The dual carbon–graphene matrix not only improves the electronic conductivity but also stabilizes the electrode material effectively. In addition, the Se substitution within the CoS₂ lattice further improves the electrical conductivity and promotes the Na⁺ reaction kinetics. The enhanced intrinsic electronic/ionic conductivity and reinforced structural stability endow the Se-CoS₂/C@rGO anode with a high reversible capacity (558.2 mAh g⁻¹ at 0.2 A g⁻¹), superior rate performance (351 mAh g⁻¹ at 20 A g⁻¹), and long cycle life (93.5% capacity retention after 2100 cycles at 1 A g⁻¹). This work provides new insights into the development of stable and reversible anode materials through Se substitution and dual carbon encapsulation. Full article

The reactivity of nitrogen oxide, NO, as a ligand in complexes with [Fe2-S2] and [Co2-S2] non-planar rhombic cores is examined by density functional theory (DFT). The cobalt-containing nitrosyl complexes are less stable than the iron complexes because the Co-S bonds in the [Co2-S2] core are weakened upon NO coordination. Various positions of NO were examined, including its binding to sulfur centers. The release of NO molecules can be monitored photochemically. The ability of NO to form a (NO)₂ dimer provides a favorable route of electrochemical reduction, as protonation significantly stabilizes the dimeric species over the monomers. The quasilinear dimer ONNO, with trans-orientation of oxygen atoms, gains higher stability under protonation and reduction via proton–electron transfer. The first two reduction steps lead to an N₂O intermediate, whose reduction is more energy demanding: in the two latter reaction steps the highest energy barrier for Co₂S₂(CO)₆ is 109 kJ mol⁻¹, and for Fe₂S₂(CO)₆, it is 133 kJ mol⁻¹. Again, the presence of favorable light absorption bands allows for a photochemical route to overcome these energy barriers. All elementary steps are exothermic, and the final products are molecular nitrogen and water. Full article

Two-dimensional (2D) sulfide-based transition metal dichalcogenides (TMDs) have shown their crucial importance in energy storage devices. In this study, the tungsten disulfide (WS₂) nanosheets were combined with hydrothermally synthesized cobalt magnesium sulfide (CoMgS) nanocomposite for use as efficient electrodes in supercapattery energy storage devices. The characteristics of the WS₂@CoMgS nanocomposite were better than those of the WS₂ and CoMgS electrodes. XRD, SEM, and BET analyses were performed on the nanocomposite to examine its structure, morphology, and surface area in depth. In three-electrode assemblies, the composite (WS₂@CoMgS) electrode showed a high specific capacity of 874.39 C g⁻¹ or 1457.31 F g⁻¹ at 1.5 A g⁻¹. The supercapattery device (WS₂@CoMgS//AC) electrode demonstrated a specific capacity of 325 C g⁻¹ with an exceptional rate capability retention of 91% and columbic efficiency of 92% over 7000 cycles, according to electrochemical studies. Additionally, the high energy storage capacity of the WS₂@CoMgS composite electrode was proved by structural and morphological investigations. Full article

The syntheses and structural elucidation of bimetallic thiolate complexes of early and late transition metals are described. Thermolysis of the bimetallic hydridoborate species [{Cp*CoPh}{µ-TePh}{µ-TeBH₃-ĸ²Te,H}{Cp*Co}] (Cp* = ɳ⁵-C₅Me₅) (1) in the presence of CS₂ afforded the bimetallic perthiocarbonate complex [(Cp*Co)₂(μ-CS₄-κ¹S:κ²S′)(μ-S₂-κ²S″:κ¹S‴)] (2) and the dithiolene complex [(Cp*Co)(μ-C₃S₅-κ¹S,S′] (3). Complex 2 contains a four-membered metallaheterocycle (Co₂S₂) comprising a perthiocarbonate [CS₄]²⁻ unit and a disulfide [S₂]²⁻ unit, attached opposite to each other. Complex 2 was characterized by employing different multinuclear NMR, infrared spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies. Preliminary studies show that [Cp*VCl₂]₃ (4) with an intermediate generated from CS₂ and [LiBH₄·THF] yielded thiolate species, albeit different from the cobalt system. Furthermore, a computational analysis was performed to provide insight into the bonding of this bimetallic perthiocarbonate complex. Full article

It is imperative to develop an efficient catalyst to reduce the energy barrier of electrochemical water decomposition. In this study, a well-designed electrocatalyst featuring a core–shell structure was synthesized with cobalt sulfides as the core and molybdenum disulfide nanosheets as the shell. The core–shell structure can prevent the agglomeration of MoS₂, expose more active sites, and facilitate electrolyte ion diffusion. A CoS₂/MoS₂ heterostructure is formed between CoS₂ and MoS₂ through the chemical interaction, and the surface chemistry is adjusted. Due to the morphological merits and the formation of the CoS₂/MoS₂ heterostructure, CoS₂@MoS₂ exhibits excellent electrocatalytic performance during the oxygen evolution reaction (OER) process in an alkaline electrolyte. To reach the current density of 10 mA cm⁻², only 254 mV of overpotential is required for CoS₂@MoS₂, which is smaller than that of pristine CoS₂ and MoS₂. Meanwhile, the small Tafel slope (86.9 mV dec⁻¹) and low charge transfer resistance (47 Ω) imply the fast dynamic mechanism of CoS₂@MoS₂. As further confirmed by cyclic voltammetry curves for 1000 cycles and the CA test for 10 h, CoS₂@MoS₂ shows exceptional catalytic stability. This work gives a guideline for constructing the core–shell heterostructure as an efficient catalyst for oxygen evolution reaction. Full article

Carbamazepine (CBZ), as a typical pharmaceutical and personal care product (PPCP), cannot be efficiently removed by the conventional drinking water and wastewater treatment process. In this work, the CoS₂/Fe²⁺/PMS process was applied for efficient elimination of CBZ. The CBZ removal efficiency of CoS₂/Fe²⁺/PMS was 2.5 times and 23 times higher than that of CoS₂/PMS and Fe²⁺/PMS, respectively. The intensity of DMPO-HO• and DMPO-${\mathrm{SO}}_4^{•-}$ followed the order of Fe²⁺/PMS < CoS₂/PMS < CoS₂/Fe²⁺/PMS, also suggesting the CoS₂/Fe²⁺/PMS process has the highest oxidation activity. The effects of reaction conditions (e.g., CoS₂ dosage, Fe²⁺ concentration, PMS concentration, initial CBZ concentration, pH, temperature) and water quality parameters (e.g., ${\mathrm{SO}}_4^{2-}$, ${\mathrm{NO}}_3^{-}$, ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$, ${\mathrm{Cl}}^{-}$, ${\mathrm{NH}}_4^{+}$, humic acid) on the degradation of CBZ were also studied. Response surface methodology analysis was carried out to obtain the best conditions for the removal of CBZ, which are: Fe²⁺ = 70 µmol/L, PMS = 240 µmol/L, CoS₂ = 0.59 g/L. The sustainability test demonstrated that the repeated use of CoS₂ for 8 successive cycles resulted in little function decrease (<10%). These findings suggest that CoS₂/Fe²⁺/PMS may be a promising method for advanced treatment of tailwater from sewage treatment plant. Full article

A relationship between carbon monoxide (CO) and hydrogen sulfide (H₂S) has been described in different pathological conditions, but their interaction in modulating joint pain has not yet been investigated. In young female mice with monosodium acetate-induced joint degeneration and pain, we assessed: (1) the effects of CORM-2 (tricarbonyldichlororuthenium(II)dimer), a CO-releasing molecule, and CoPP (cobalt protoporphyrin IX), an inducer of heme oxygenase 1 (HO-1), administered alone and combined with low doses of two slow-releasing H₂S donors, DADS (diallyl disulfide) and GYY4137 (morpholin-4-ium 4-methoxyphenyl(morpholino) phosphinodithioate dichloromethane complex) on the mechanical allodynia and loss of grip strength provoked by joint degeneration; (2) the role of Nrf2, NAD(P)H: quinone oxidoreductase 1 (NQO1) and HO-1 in the antinociceptive actions of H₂S donors; (3) the impact of DADS and GYY4137 treatment on the expression of Nrf2 and several antioxidant proteins in dorsal root ganglia (DRG) and periaqueductal gray matter (PAG). Our data showed that treatment with H₂S donors inhibited allodynia and functional deficits, while CORM-2 and CoPP only prevented allodynia. The Nrf2 pathway is implicated in the analgesic actions of DADS and GYY4137 during joint degeneration. Moreover, the co-administration of low doses of CORM-2 or CoPP with DADS or GYY4137 produced higher antiallodynic effects and greater recovery of grip strength deficits than those produced by each of these compounds alone. The activation of the antioxidant system caused by H₂S donors in DRG and/or PAG might explain the enhancement of antinociceptive effects. These data reveal a positive interaction between H₂S and CO in modulating joint pain in female mice. Full article

Densely aligned CoS₂ nanowires (NWs) on chemically durable stainless steel fibers felt (SSF) substates were synthesized by thermal sulfuring Co₃O₄ NWs, which were oxidized from hydrothermal synthesized Co(OH)_y(CO₃)_(1−0.5y)·nH₂O NWs precursors. The effect of sulfuration temperature on the composition, morphology, and HER performance of the products was studied in detail. The results show that the high purity together with the enlarged density of active sites given by the twisted morphology of the CoS₂ NWs sulfured at 500 °C guarantee its superior hydrogen evolution reaction (HER) performance compared with other samples sulfured at lower temperatures. Full article

In this work, a novel three-dimensional (3D) hollow nickel-cobalt layered double hydroxide (NiCo-LDH) was synthesized using zeolitic imidazole framework-67 (ZIF-67) as a template, and then utilized to functionalize molybdenum disulfide (NiCo-LDH/MoS₂) via electrostatic force. Flame retardant thermoplastic polyurethane (TPU) composites were prepared by the melt blending method. Compared to pure TPU, NiCo-LDH/MoS₂ filled TPU composite was endowed with a decrease of 30.9% and 55.7% of the peak heat release rate (PHRR) and the peak smoke production rate (PSPR), respectively. Furthermore, the addition of NiCo-LDH/MoS₂ can significantly improve the thermal stability and char yield of the TPU composite. The catalytic carbonization effect and dilution effect of NiCo-LDH, and the barrier effect of MoS₂ nanosheets enable TPU composites with excellent flame retardancy and toxic gas suppression ability. Full article

The strictly conserved αSer162 residue in the Co-type nitrile hydratase from Pseudonocardia thermophila JCM 3095 (PtNHase), which forms a hydrogen bond to the axial αCys108-S atom, was mutated into an Ala residue. The αSer162Ala yielded two different protein species: one was the apoform (αSer^A) that exhibited no observable activity, and the second (αSer^B) contained its full complement of cobalt ions and was active with a k_cat value of 63 ± 3 s⁻¹ towards acrylonitrile at pH 7.5. The X-ray crystal structure of αSer^A was determined at 1.85 Å resolution and contained no detectable cobalt per α₂β₂ heterotetramer. The axial αCys108 ligand itself was also mutated into Ser, Met, and His ligands. All three of these αCys108 mutant enzymes contained only half of the cobalt complement of wild-type PtNHase, but were able to hydrate acrylonitrile with k_cat values of 120 ± 6, 29 ± 3, and 14 ± 1 s⁻¹ for the αCys108His, Ser, and Met mutant enzymes, respectively. As all three of these mutant enzymes are catalytically competent, these data provide the first experimental evidence that transient disulfide bond formation is not catalytically essential for NHases. Full article

Dye-sensitized solar cells (DSSCs) emerged in the early 1990s as a promising alternative to the classic silicon-based solar cell due to their unique combination of low cost, ease of fabrication, color palette for building integration, and high efficiency in indoor applications. This review article describes the fabrication and the properties of poly (3,4-ethylenedioxythiophene) (PEDOT)-based catalytic counter electrodes (CEs) for DSSCs. In particular, the electrochemical reactivity PEDOT CEs used in conjunction with alternative redox mediators for DSSCs is outlined. Among alternative redox shuttles, cobalt and copper complexes, as well as totally organic thiolate/disulfide, have been considered. Finally, PEDOT can also be used as a hole conductor material in electrolyte-free solid-state dye-sensitized solar cells. This review clearly shows that the progress in DSSCs development is strongly linked to the introduction of PEDOT as a new counter electrode material. Full article

The design of novel materials to use simultaneously in an ocular system for driven therapeutics and wound healing is still challenging. Here, we produced nanocomposites of tungsten disulfide carriers with spherical cobalt ferrite nanoparticles (NPs) as core inside a cubic iron oxide NPs shell (WS₂/s-CoFe₂O₄@c-Fe₃O₄). Transmission electron microscopy (TEM) confirmed that 10 nm s-CoFe₂O₄@c-Fe₃O₄ NPs were attached on the WS₂ sheet surfaces. The cytotoxicity of the WS₂ sheets and nanocomposites were evaluated on bovine cornea endothelial cells (BCECs) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for a duration of three days. The MTT assay results showed low toxicity of the WS₂ sheets on BCECs by 67% cell viability at 100 μg/mL in 24 h, while the nanocomposites show 50% cell viability in the same conditions. The magnetic resonance imaging (MRI) of nanocomposites revealed the excellent T₂-weighted imaging with an r₂ contrast of 108 mM⁻¹ S⁻¹. The in vitro photothermal therapy based on WS₂ sheets and WS₂/s-CoFe₂O₄ @c-Fe₃O₄ nanocomposites using 808 nm laser showed that the maximum thermal energy dispatched in medium at different applied power densities (1200 mw, 1800, 2200, 2600 mW) was for 0.1 mg/mL of the sample solution. The migration assay of BCECs showed that the wound healing was approximately 20% slower for the cell exposed by nanocomposites compared with the control (no exposed BCECs). We believe that WS₂/s-CoFe₂O₄@c-Fe₃O₄ nanocomposites have a synergic effect as photothermal therapy agents for eye diseases and could be a target in an ocular system using MRI. Full article