Hydrogen Bond between Molybdate and Glucose for the Formation of Carbon-Loaded MoS2 Nanocomposites with High Electrochemical Performance

Removal of Mo(VI), Pb(II), and Cu(II) from wastewater using electrospun cellulose acetate/chitosan biopolymer fibers

Environmentally friendly polymers such as cellulose acetate (CA) and chitosan (CS) were used to obtain electrospun fibers for Cu2+, Pb2+, and Mo6+ capture. The solvents dichloromethane (DCM) and dimethylformamide (DMF) allowed the development of a surface area of 148 m2 g-1 for CA fibers and 113 m2 g-1 for cellulose acetate/chitosan (CA/CS) fibers. The fibers were characterized by IR-DRIFT, SEM, TEM, CO2 sorption isotherms at 273 K, Hg porosimetry, TGA, stress-strain tests, and XPS. The CA/CS fibers had a higher adsorption capacity than CA fibers without affecting their physicochemical properties. The capture capacity reached 102 mg g-1 for Cu2+, 49.3 mg g-1 for Pb2+, and 13.1 mg g-1 for Mo6+. Furthermore, optimal pH, adsorption times qt, and C0 were studied for the evaluation of kinetic models and adsorption isotherms. Finally, a proposal for adsorbate-adsorbent interactions is presented as a possible capture mechanism where, in the case of Mo6+, a computational study is presented. The results demonstrate the potential to evaluate the fibers in tailings wastewater from copper mining.

Gram-Scale Mechanochemical Synthesis of Atom-Layer MoS2 Semiconductor Electrocatalyst via Functionalized Graphene Quantum Dots for Efficient Hydrogen Evolution

The development of advanced and efficient synthetic methods is pivotal for the widespread application of 2D materials. In this study, a facile and scalable solvent-free mechanochemical approach is approached, employing graphene quantum dots (GQDs) as exfoliation agents, for the synthesis and functionalization of nearly atom-layered MoS2 nanosheets (ALMS). The resulting ALMS exhibits an ultrathin average thickness of 4 nm and demonstrates high solvent stability. The impressive yield of ALMS reached 63%, indicating its potential for scalable production of stable nanosheets. Remarkably, the ALMS catalyst exhibits excellent HER performance. Moreover, the ALMS catalyst showcases exceptional long-term durability, maintaining stable performance for nearly 200 h, underscoring its potential as a highly efficient and durable electrocatalyst. Significantly, the catalytic properties of ALMS are significantly influenced by ball milling production conditions. The GQD-assisted large-scale machinery synthesis pathway provides a promising avenue for the development of efficient and high-performance ultrathin 2D materials.

Growth of polyoxomolybdate with a porous pyramidal structure on carbon xerogel nanodiamond as an efficient electro-catalyst for oxygen reduction reaction

The slow kinetics of the oxygen reduction reaction (ORR) limits the large-scale usage of the fuel cells. Thus, it is crucial to develop an efficient and stable electrocatalyst for the ORR. Herein, facile synthesis of three-dimensional nitrogen-doped carbon xerogel diamond nanoparticles, CDNPs support is reported. The as-prepared CDNPs support was functionalized with a Keggin-type polyoxomolybdate via the hydrothermal process (POM@CDNPs). As the characterization techniques revealed, this nanocomposite possesses a three-dimensional structure, high density of nitrogen doping, and well-dispersed porous pyramidal morphology of POM, making it a promising catalyst for ORR in alkaline medium. The POM@CDNPs nanocomposite exhibits an outstanding activity for ORR with a limiting current density that reaches -7.30 mA cm^-2 at 0.17 V vs. RHE. Moreover, a half-wave potential of 0.773 V is delivered with a stability of about 99.9% after the 100th repetitive cycle as this catalyst forces the ORR to the direct-four-electron pathway. This work spots the advantages of hybridizing the sp³ of the nanodiamond with the sp² of the carbon xerogels to increase the conductivity of the support material. In addition, the role of the porous pyramidal morphology of the POM on the activity of the nanocomposite was evaluated. This study suggests using advanced carbon-based electro-catalysts with outstanding activity and stability.

Anchoring polysulfides via a CoS2/NC@1T MoS2 modified separator for high-performance lithium–sulfur batteries

CoS2/NC@1T MoS2 synthesized by a one-step hydrothermal method forms a unique hierarchical configuration with simultaneous internal and external modifications. A lithium–sulfur battery with a CoS2/NC@1T MoS2-PP separator shows superior cycling performance.

A hierarchical hollow Ni/Co-functionalized MoS2 architecture with highly sensitive non-enzymatic glucose sensing activity

A hierarchical hollow Ni/Co-codoped MoS2 architecture was successfully prepared using a Ni/Co Prussian Blue analogue as the precursor followed by the solvothermal-assisted insertion of MoS42- and extraction of [Co(CN)6]3- at 200 °C for 32 h. The obtained Ni/Co-codoped MoS2 composite exhibited a hollow microcubic structural characteristic, and the morphology, structure, and chemical compositions were carefully characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. The Ni/Co-codoped MoS2 composite used as an electrode material featured excellent glucose sensing activity and a high sensitivity of 2546 μA mM-1 cm-2 with a relatively low detection limit of 0.69 μM (S/N = 3). In addition, the Ni/Co-codoped MoS2 composite showed good anti-interference sensing performance in the presence of ascorbic acid (AA), lysine (Lys), cysteine (Cys), urea, H2O2, KCl, and other interferents. These experimental results revealed that the composite is a promising electrode material for enzyme-free glucose sensing, and the feasible synthetic strategy may provide an effective and controlled route to prepare other multi-metal substituted sulfide-based hierarchical structures with high electrochemical sensing performance.

Plasma-Induced Exfoliation Provides Onion-Like Graphene-Surrounded MoS2 Nanosheets for a Highly Efficient Hydrogen Evolution Reaction

With the goal of obtaining sustainable earth-abundant electrocatalyst materials displaying high performance in the hydrogen evolution reaction (HER), here we propose a facile one-pot plasma-induced electrochemical process for the fabrication of new core-shell structures of ultrathin MoS₂ nanosheets engulfed within onion-like graphene nanosheets (OGNs@MoS₂). The resultant OGNs@MoS₂ structures not only increased the number of active sites of the semiconducting MoS₂ nanosheets but also enhanced their conductivity. Our OGNs@MoS₂ composites exhibited high HER performance, characterized by a low overpotential of 118 mV at a current density of 10 mA cm^-2, a Tafel slope of 73 mV dec^-1, and long-time stability of 10⁵ s without degradation; this performance is much better than that of the sheet-like graphene-wrapped MoS₂ composite GNs@MoS₂ (182 mV, 82 mV dec^-1) and is among the best ever reported for composites involving MoS₂ and graphene nanosheets prepared through a simple one-batch process and using a low temperature and a short time for the HER. This approach appears to be an effective and simple strategy for tuning the morphologies of composites of graphene and transition metal dichalcogenide materials for a broad range of energy applications.