Fairy Fan Yang

Abstract 2D molybdenum disulfide (MoS 2 ) is developed as a potential alternative non‐precious metal electrocatalyst for energy conversion. It is well known that 2D MoS 2 has three main phases 2H, 1T, and 1T′. However, the most stable 2H‐phase shows poor electrocatalysis in its basal plane, compared with its edge sites. In this work, a facile one‐step hydrothermal‐driven in situ porousizing of MoS 2 into self‐supporting nano islands to maximally expose the edges of MoS 2 grains for efficient utilization of the active stable sites at the edges of MoS 2 is reported. The results show that such active, aggregation‐free nano islands greatly enhance MoS 2 's hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctional electrocatalytic activities. At a low overpotential of 248 and 300 mV, the porous MoS 2 nano islands can generate a current density of 10 mA cm −2 in HER and OER, which is much better than typical nanosheet morphology. Surprisingly, the porous MoS 2 nano islands even exhibit better performance than the current commercial RuO 2 catalyst in OER. This discovery will be another effective strategy to promote robust 2H‐phase, instead of 1T/1T′‐phase, MoS 2 to achieve efficient endurable bifunctional HER/OER, which is expected to further replace precious metal catalysts in industry.

Two-dimensional transition metal dichalcogenides (2D TMDs) present promising applications in various fields such as electronics, optoelectronics, memory devices, batteries, superconductors, and hydrogen evolution reactions due to their regulable energy band structures and unique properties. For emerging spintronics applications, materials with excellent room-temperature ferromagnetism are required. Although most transition metal compounds do not possess room-temperature ferromagnetism on their own, they are widely modified by researchers using the emerging strategies to engineer or modulate their intrinsic properties. This paper reviews recent enhancement approaches to induce magnetism in 2D TMDs, mainly using doping, vacancy defects, composite of heterostructures, phase modulation, and adsorption, and also by electron irradiation induction, O plasma treatment, etc. On this basis, the produced effects of these methods for the introduction of magnetism into 2D TMDs are compressively summarized and constructively discussed. For perspective, research on magnetic doping techniques for 2D TMDs materials should be directed toward more reliable and efficient directions, such as exploring advanced design strategies to combine dilute magnetic semiconductors, antiferromagnetic semiconductors, and superconductors to develop new types of heterojunctions; and advancing experimentation strategies to fabricate the designed materials and enable their functionalities with simultaneously pursuing the upscalable growth methods for high-quality monolayers to multilayers.

• A novel bimetallic MOFs with a stable and special framework structure was developed. • Framework structure solved problem of easy aggregation and collapse of Mo 2 C material. • High specific surface area 3D Co-Mo x N/Mo 2 C provide more HER/OER catalytic active sites. Metal organic frameworks (MOFs) are widely used as precursors due to their tunable morphology and high specific surface area. Molybdenum nitride (MoN) and molybdenum carbide (Mo 2 C) are promising catalyst materials with electronic structures similar to the noble metal platinum. However, the preparation and modification of the composite systems comprising MoN and Mo 2 C are complex, often leading to significant agglomeration and limiting their application in various catalytic fields. In this work, we designed and developed a novel bimetallic Co-MOFs-Mo with a stable and unique framework morphology. By varying the organic ligand content, we controlled the morphology and enhanced the intrinsic electrocatalytic activity through Mo doping. Using the Co-MOFs-Mo sample as the Co source, we fabricated a Co-Mo x N/Mo 2 C catalytic material with a special framework structure. Compared to Mo 2 N and Mo 2 N/Mo 2 C, this catalyst exhibits a larger specific surface area and superior performance in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The Co-Mo x N/Mo 2 C catalyst achieves an HER overpotential of 297 mV at a current density of 10 mA·cm −2 and an OER overpotential of 480 mV at 20 mA·cm −2 . This research provides valuable insights into the rational design of molybdenum-based noble-metal-free catalyst materials.

Abstract 2D 2H‐phase MoS 2 is promising for electrocatalytic applications because of its stable phase, rich edge sites, and large surface area. However, the pristine low‐conductive 2H‐MoS 2 suffers from limited electron transfer and surface activity, which become worse after their highly likely aggregation/stacking and self‐curling during applications. In this work, these issues are overcome by conformally attaching the intercalation‐detonation‐exfoliated, surface S‐vacancy‐rich 2H‐MoS 2 onto robust conductive carbon nanotubes (CNTs), which electrically bridge bulk electrode and local MoS 2 catalysts. The optimized MoS 2 /CNTs nanojunctions exhibit outstanding stable electroactivity (close to commercial Pt/C): a polarization overpotential of 79 mV at the current density of 10 mA cm −2 and the Tafel slope of 33.5 mV dec −1 . Theoretical calculations unveil the metalized interfacial electronic structure of MoS 2 /CNTs nanojunctions, enhancing defective‐MoS 2 surface activity and local conductivity. This work provides guidance on rational design for advanced multifaceted 2D catalysts combined with robust bridging conductors to accelerate energy technology development.