Few-Layered WS2 Anchored on Co, N-Doped Carbon Hollow Polyhedron for Oxygen Evolution and Hydrogen Evolution

Synergistic Effects of Dual-Doping with Ni and Ru in Monolayer VS2 Nanosheet: Unleashing Enhanced Performance for Acidic HER through Defects and Strain

Amidst the escalating quest for clean energy, the hydrogen evolution reaction (HER) in acidic conditions has taken center stage, catalyzing the search for advanced electrocatalysts. The efficacy of these materials is predominantly dictated by the active site density on their surfaces. The propensity is leveraged for monolayer architectures to introduce defects, enhancing surface area, and increasing active sites. Doping enhances defects and fine-tunes catalyst activity. In this vein, defect-enriched monolayer nanosheets doped with nickel and a trace amount of ruthenium in VS2 (SL-Ni-Ru-VS2) are engineered and characterized. Evaluation in 0.5 m H2SO4 solution unveils that the catalyst achieves overpotentials as low as 20 and 41 mV at current densities of -10 and -100 mA cm⁻2. Impressively, the catalyst maintains a mass activity of 13.08 A mg⁻¹Ru, even with minimal Ru incorporation, indicating exceptional catalytic efficiency. This monolayer catalyst sustains its high activity at lower overpotentials, demonstrating its practical applicability. The comprehensive analysis, which combines experimental data and computational simulations, indicates that the co-doping of Ni and Ru enhances the electrocatalytic properties of VS2. This research offers a strategic framework for crafting cutting-edge electrocatalysts specifically designed for enhanced performance in the HER.

Synthesis and Electrocatalytic Applications of Layer-Structured Metal Chalcogenides Composites

Featured with the attractive properties such as large surface area, unique atomic layer thickness, excellent electronic conductivity, and superior catalytic activity, layered metal chalcogenides (LMCs) have received considerable research attention in electrocatalytic applications. In this review, the approaches developed to synthesize LMCs-based electrocatalysts are summarized. Recent progress in LMCs-based composites for electrochemical energy conversion applications including oxygen reduction reaction, carbon dioxide reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, overall water splitting, and nitrogen reduction reaction is reviewed, and the potential opportunities and practical obstacles for the development of LMCs-based composites as high-performing active substances for electrocatalytic applications are also discussed. This review may provide an inspiring guidance for developing high-performance LMCs for electrochemical energy conversion applications.

Heterostructure CoS2/MoS2 Nanosheets as a Dual-Active Electrocatalyst for the Oxygen Evolution Reaction

Cost-effective and earth-abundant oxygen evolution reaction (OER) electrocatalysts are an incredible research hotspot in numerous energy storage and conversion technology fields. Herein, CoS2/MoS2 nanosheets supported by carbon cloth as a dual-active CC@CoS2/MoS2 heterostructure electrocatalyst is prepared through a simple solvothermal method. The catalyst demonstrates admirable OER performance in 1 M KOH solution with a low overpotential of 243 mV at a current density of 10 mA cm-2 and a minor Tafel slope of 109 mV dec-1, displaying honorable stability after 1000 cyclic voltammetry (CV) cycles and long-term robustness over 60 h. Theoretical calculations further ascertain that the rate-determining step of the electrocatalytic course of the CC@CoS2/MoS2 heterostructure is the conversion *O + OH- → *OOH + e- with a lower energy barrier of 1.49 eV due to the heterojunction established by CoS2 and MoS2, which can promote the OER performance of electrocatalysts. The actual identification of the catalytic mechanism in the heterostructure is conducive to the improvement of electrocatalysis applications in the OER.

Regulating the Spin State of Metal and Metal Carbide Heterojunctions for Efficient Oxygen Evolution

Developing high-performance electrocatalysts for oxygen evolution reaction (OER) is of importance for improving the overall efficiency of water splitting. Herein, the CoFe/(Co_xFe_1-x)₃Mo₃C heterojunction is purposely designed as an OER catalyst, which displays a low overpotential of 293 mV for affording a current density of 10 mA cm^-2 and a small Tafel slope of 48 mV/dec. Various characterization results demonstrate that the significant work-function difference between CoFe and (Co_xFe_1-x)₃Mo₃C can induce interfacial charge redistribution, which results in the formation of Co and Fe sites with a high-spin state, thus stimulating the surface phase reconstruction of CoFe/(Co_xFe_1-x)₃Mo₃C to corresponding active oxyhydroxide. Meanwhile, the electrochemical leaching of Mo ions from the initial structure can contribute to the formation of defective sites, further benefiting OH^- adsorption and surface oxidation. Moreover, the remaining CoFe can accelerate electron migration during the electrocatalytic process. This study presents new insights into constructing efficient OER electrocatalysts with an optimized spin-state configuration via interfacial engineering.

Dual CoxSy-Modified Tungsten Disulfide Double-Heterojunction Electrocatalyst for Efficient Hydrogen Evolution in All-pH Media

The rational design and preparation of a heterogeneous electrocatalyst for hydrogen evolution reaction (HER) has become a research hotspot, while applicable and pH-universal tungsten disulfide (WS₂)-based hybrid composites are rarely reported. Herein, we propose a novel hybrid catalyst (WS₂/Co₉S₈/Co₄S₃) comprising two heterojunctions of WS₂/Co₄S₃ and WS₂/Co₉S₈, which grow on the porous skeleton of Co, N-codoped carbon (Co/NC) flexibly applicable to all-pH electrolytes. The effect of double heterogeneous coupling on HER activity is explored as the highly flexible heterojunction is conducive to tune the activity of the catalyst, and the synergistic interaction of the double heterojunctions is maximized by adjusting the proportion of heterojunction components. Theoretical calculations show that both WS₂/Co₉S₈ and WS₂/Co₄S₃ heterojunctions have a Gibbs free energy of H reaction (|ΔG_H*|) close to 0.0 eV and a facile decomposition water barrier. As collective synergy of dual Co_xS_y-modified WS₂ double heterojunction, WS₂/Co₉S₈/Co₄S₃ greatly enhances HER activity compared to bare Co₉S₈/Co₄S₃ or single heterojunction (WS₂/Co₉S₈) in all-pH media. Besides, we have elucidated the unique HER mechanism of the double heterojunction to decompose H₂O and confirm its excellent activity under alkaline and neutral conditions. Thus, this work provides new insights into WS₂-based hybrid materials potentially applied to sustainable energy.