Yanfeng Zhang

Two‐dimensional metallic transition‐metal dichalcogenides provide conductive and catalytically active surfaces, while three‐dimensional porous metal frameworks offer continuous transport pathways and mechanical robustness. Hybridizing these complementary structures into a monolithic architecture is attractive for electrochemical interface engineering, but it remains challenging to integrate their advantages into a single component that coordinates mass transport, interfacial contact, and surface reactivity. Herein, we develop a multifunctional monolithic TaS ₂ /3D‐Ta gas diffusion layer (GDL) by 3D printing a porous Ta scaffold followed by a direct sulfurization process to form vertically‐aligned TaS ₂ nanosheet networks. The resulting monolith features ordered, thorough pores (∼285.7 µm mean pore size), low interfacial resistances (∼2 mΩ cm ² at 150 N cm ⁻² ), and high electrocatalytic hydrogen evolution activity (Tafel slope of ∼55.3 mV dec ⁻¹ ), thereby functioning as a high‐porosity transport framework, a contact‐optimized interface, and a catalytically active surface. The designed TaS ₂ /3D‐Ta is further demonstrated as an efficient cathodic GDL in a proton‐exchange‐membrane water electrolysis cell, affording a lower working voltage (by ∼0.54 V) at 2 A cm ⁻² than that of commercial carbon paper GDL. This work hereby provides a monolithic hybridization strategy for constructing multifunctional electrochemical interface materials.

The catalytic performance of two‐dimensional (2D) transition metal dichalcogenides (TMDs) for the hydrogen evolution reaction (HER) is severely limited by the scarcity of active edge sites and intrinsically inert basal planes. Although Janus TMDs mitigates this issue by activating the basal plane through an inherent vertical asymmetry structure and synthesis‐induced chalcogen vacancies, achieving a high density of edge sites and exploring their interplay with Janus dipole remains a critical challenge. Herein, we demonstrate a strain‐driven crack engineering strategy for monolayer Janus WSeS. The lattice strain inherent in the room‐temperature sulfurization conversion from WSe ₂ to Janus WSeS spontaneously induces a dense distribution of nanoscale cracks, creating abundant active edges. In addition, these crack edges synergistically interact with sulfur vacancies to modulate the electronic states near E _F and optimize the hydrogen adsorption/desorption kinetics for enhanced HER activity. The resulting material achieves outstanding HER performance in acidic electrolyte, with a low overpotential of 214 mV at 10 mA cm ⁻² and a Tafel slope of 68 mV dec ⁻¹ . This work provides an approach to precisely tailor edge morphology in 2D materials, bridging the structure–performance relationship for advanced electrocatalysis.

The catalytic performance of two‐dimensional (2D) transition metal dichalcogenides (TMDs) for the hydrogen evolution reaction (HER) is severely limited by the scarcity of active edge sites and intrinsically inert basal planes. Although Janus TMDs mitigates this issue by activating the basal plane through an inherent vertical asymmetry structure and synthesis‐induced chalcogen vacancies, achieving a high density of edge sites and exploring their interplay with Janus dipole remains a critical challenge. Herein, we demonstrate a strain‐driven crack engineering strategy for monolayer Janus WSeS. The lattice strain inherent in the room‐temperature sulfurization conversion from WSe ₂ to Janus WSeS spontaneously induces a dense distribution of nanoscale cracks, creating abundant active edges. In addition, these crack edges synergistically interact with sulfur vacancies to modulate the electronic states near E _F and optimize the hydrogen adsorption/desorption kinetics for enhanced HER activity. The resulting material achieves outstanding HER performance in acidic electrolyte, with a low overpotential of 214 mV at 10 mA cm ⁻² and a Tafel slope of 68 mV dec ⁻¹ . This work provides an approach to precisely tailor edge morphology in 2D materials, bridging the structure–performance relationship for advanced electrocatalysis.

MoS2 nanoscrolls can be intrinsically chiral quasi-1D materials, yet the influence of chirality on their electrical characteristics remains unresolved, since chirality metrology and device measurement have rarely been achieved on the same individual scrolls. In this work, we integrate polarization-resolved second-harmonic generation (SHG) with transistor characterization on MoS2 nanoscroll devices to address this long-standing question. We develop a unified SHG fitting model to extract an effective chiral angle (φ) for each scroll and establish a systematic correlation between transfer characteristics and structural parameters. The on-state current decreases with increasing |φ| and is further influenced by a strain-related parameter, whereas the off-state current correlates more closely with an SHG-derived winding/thickness indicator, consistent with electrostatic screening in multi-turn channels. These findings clarify the role of chirality and related geometric parameters in defining the transport properties of low-dimensional systems and provide useful insights for chirality-based nanoelectronics.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) single-crystal wafers have been envisioned as promising channel materials to drive semiconductor technology down to the atomic limit. Although several efforts have been made, wafer-scale single crystal growth with high robustness and efficiency remains challenging. Here, we design a homo-metal-element (W/Mo and Al) surface modification strategy of commercial C/M sapphire inducing a low-symmetry modification layer. This design enables the robust epitaxial growth of 2-inch scale monolayer WS₂ or MoS₂ single-crystal wafers via a facile chemical vapor deposition (CVD) method. Since no exogenous elements are introduced on the substrate surface, the derived monolayer WS₂ single crystals present high crystal quality and no impurity introduction, as evidenced by multi-scale characterizations and field effect transistors array fabrications (on/off ratio >10⁸ and mobility ~48.2 cm²V⁻¹ s⁻¹). This work should hereby propel the wafer-scale synthesis and the internal epitaxial mechanism exploration of 2D TMDCs single crystals via substrate surface modulation, and promote the high-performance applications in various fields.

Generally, ideal transition metal dichalcogenides (TMDCs) based catalysts should possess vertical nanosheet morphology with abundant edge sites, and superior crystal phase with intrinsically high catalytic property in hydrogen evolution reaction (HER), while the two merits are hard to be combined together. Herein, we report the abnormal vertical growth of high‐density TaS ₂ nanosheets on planar Au substrates, by designing a “precursor‐migration‐prohibited” nucleation and growth process via the atmospheric pressure chemical vapor deposition (APCVD) route. Moreover, we uncover that, high/low growth temperature is the dominant factor for the phase‐selective growth of 2H/1T‐phase TaS ₂ on planar Au substrates. Four typical catalytic systems of vertical or horizontal 2H‐TaS ₂ /Au and 1T‐TaS ₂ /Au are thus achieved, with the vertical 2H‐TaS ₂ /Au catalyst showing ultrahigh electrocatalytic property in HER, featuring rather low overpotential and Tafel slope of ∼53 mV, ∼59 mV/dec, and an ultra‐high exchange current density of ∼1422 µA cm ⁻² . Hereby, this work should provide valuable insights into the synergistic modulation of morphology and phase of metallic TMDCs toward catalytic property upgrade in the energy conversion related fields.

2D iron chalcogenides (FeX, X = S, Se, Te) are emerging as an appealing class of materials, owing to their intriguing physical properties (e.g., 2D magnetism, interface superconductivity), and great potentials in next‐generation applications (e.g., spintronics, quantum computing). Recently, FeS has attracted particular attentions due to the discovery of altermagnetism in bulk state. However, the intrinsic physical properties of 2D FeS are still unclear, since the syntheses of high‐quality FeS with thicknesses down to 2D limit remain challenging. Herein, we report the direct syntheses of thickness‐tunable, high‐quality 2D FeS flakes with low defect density and thus strict stoichiometry, via a space‐confined chemical vapor deposition (CVD) strategy. Significantly, we observe an unsaturated magnetoresistance with a crossover behavior (positive‐negative‐positive with decreasing the temperature from ≈350 to ≈2 K), and an ultra‐high conductivity (≈2.8 × 10 ⁷ S m ⁻¹ at 2 K) in 2D FeS. Leveraging such high conductivity and robust air stability, we demonstrate 2D FeS as ideal contact electrodes in monolayer‐MoS ₂ ‐based field effect transistor, achieving a mobility more than 3 times higher than that of Ti/Au‐contacted device. This work should hereby promote the fundamental property explorations of 2D nonlayered materials, and their applications in next‐generation electronic/spintronic devices.

2D transition metal dichalcogenides (2D TMDCs) are a group of materials possessing rich phases and versatile phase‐dependent properties, such as ferroelectricity, superconductivity, and magnetism. Phase engineering has been progressively pursued for propelling such novel property explorations and applications. Herein, this review summarizes recent advances in the phase engineering of 2D TMDCs from the perspectives of synthesis and property exploration. The electronic property modulations, novel applications in surface‐enhanced Raman scattering and electrocatalysis, and fundamental properties regarding superconductivity, ferroelectricity, and self‐intercalation‐induced magnetism will be reviewed. Diverse phase engineering strategies for synthesizing distinct phases of 2D TMDC, covering direct syntheses (e.g., chemical vapor deposition, molecular beam epitaxy, and colloidal synthesis) and phase transitions (e.g., seed epitaxy, salt‐assisted method, and electrochemical exfoliation) will be discussed. Finally, future challenges and opportunities are proposed regarding the thermal stability control, phase patterning, twist angle control, and theoretical predictions of new phases. Overall, this review provides a comprehensive summary and outlook of phase engineering strategies in 2D TMDCs and inspires in‐depth explorations into the properties and applications of unconventional 2D TMDC phases.