Precise design and synthesis of sub-nano scale catalysts with controllable electronic and geometric structures are pivotal for enhancing the hydrogen evolution reaction (HER) performance of molybdenum sulfide (MoS₂) and unraveling its structure-activity relationship. By leveraging transition molybdenum polysulfide clusters as functional units for multi-level ordering. Here, we successfully designed and synthesized MoS_x nanowire networks derived from [Mo₃S₁₃]²⁻ clusters via evaporation-induced self-assembly, which exhibit enhanced HER activity attributed to a high density of active sites and dynamic evolution behavior under cathodic potentials. MoS_x nanowire networks electrode yields a current density of 100 mA cm⁻² at 142 mV in 0.5 M H₂SO₄. This work provides an attractive prospect for optimizing catalysts at the sub-nano scale and offers insights into a strategy for designing catalysts in various gas evolution reactions.

The transition metal chalcogenides represented by MoS₂ are the ideal choice for non-precious metal-based hydrogen evolution catalysts. However, whether in acidic or alkaline environments, the catalytic activity of pure MoS₂ is still difficult to compete with Pt. Recent studies have shown that the electronic structure of materials can be adjusted by constructing lattice-matched heterojunctions, thus optimizing the adsorption free energy of intermediates in the catalytic hydrogen production process of materials, so as to effectively improve the electrocatalytic hydrogen production activity of catalysts. However, it is still a great challenge to prepare heterojunctions with lattice-matched structures as efficient electrocatalytic hydrogen production catalysts. Herein, we developed a one-step hydrothermal method to construct Ni-MoS₂@NiS₂@Ni₃S₂ (Ni-MoS₂ on behalf of Ni doping MoS₂) electrocatalyst with multiple heterogeneous interfaces which possesses rich catalytic reaction sites. The Ni-MoS₂@NiS₂@Ni₃S₂ electrocatalyst produced an extremely low overpotential of 69.4 mV with 10 mA·cm⁻² current density for hydrogen evolution reaction (HER) in 1.0 M KOH. This work provides valuable enlightenment for exploring the mechanism of HER enhancement to optimize the surface electronic structure of MoS₂, and provides an effective idea for constructing rare metal catalysts in HER and other fields.

Doping foreign metal atoms into the substrate of transition metal dichalcogenides (TMDs) enables the formation of diverse atomic structure configurations, including isolated atoms, chains, and clusters. Therefore, it is very important to reasonably control the atomic structure and determine the structure–activity relationship between the atomic configurations and the hydrogen evolution reaction (HER) performance. Although numerous studies have indicated that doping can yield diverse atomic structure configurations, there remains an incomplete understanding of the relationship between atomic configurations within the lattice of TMDs and their performance. Here, diverse atomic structure configurations of adsorptive doping, substitutional doping, and TMDs alloys are summarized. The structure–activity relationship between different atomic configurations and HER performance can be determined by micro-nanostructure devices and density functional theory (DFT) calculations. These diverse atomic structure configurations are of great significance for activating the inert basal plane of TMDs and improving the catalytic activity of HER. Finally, we have summarized the current challenges and future opportunities, offering new perspectives for the design of highly active and stable metal-doped TMDs catalysts.

The weak van der Waals gap endows two dimensional transition metal dichalcogenides (2D TMDs) with the potential to realize guest intercalation and host exfoliation. Intriguingly, the liquid intercalation and exfoliation is a facile, low-cost, versatile and scalable strategy to modulate the structure and physiochemical property of TMDs via introducing foreign species into interlayer. In this review, firstly, we briefly introduce the resultant hybrid superlattice and disperse nanosheets with tailored properties fabricated via liquid intercalation and exfoliation. Subsequently, we systematically analyze the intercalation phenomenon and limitations of various intercalants in chemical or electrochemical methods. Afterwards, we intensely discuss diverse functionalities of resultant materials, focusing on their potential applications in energy conversion, energy storage, water purification, electronics, thermoelectrics and superconductor. Finally, we highlight the challenges and outlooks for precise and mass production of 2D TMDs-based materials via liquid intercalation and exfoliation. This review enriches the overview of liquid intercalation and exfoliation strategy, and paves the path for relevant high-performance devices.

Amorphous materials are one kind of nonequilibrium materials and have become one of the most active research fields. Compared with crystalline solids, the theory of amorphous materials is still in infancy because their characteristic of atomic arrangement is more like liquid and has no long-range periodicity. Recently, as the representative of amorphous materials, amorphous molybdenum sulfide (a-MoS_x) with unique physical and chemical properties has been studied extensively. However, considerable debate surrounds the structure–property relationships of a-MoS_x owing to its diverse Mo-S motifs. Herein, we summarize recent discoveries and research results regarding a-MoS_x, whose structural characteristics, synthetic strategies, formation criteria, and comprehensive applications are discussed in detail. Finally, this review is ended with our personal insights and critical outlooks over the development of a-MoS_x.

Heteroatom doping is a promising approach to enhance catalytic activity by modulating physical properties, electronic structure, and reaction pathway. Herein, we demonstrate that appropriate Ni-doping could trigger a preferential transition of the basal plane from 2H (trigonal prismatic) to 1T′ (clustered Mo) by inducing lattice distortion and S vacancy (SV) and thus dramatically facilitate its catalytic hydrogen evolution activity. It is noteworthy that the unique catalysts did possess superior catalytic performance of hydrogen evolution reaction (HER). The rate of photocatalytic hydrogen evolution could reach 20.45 mmol·g⁻¹·h⁻¹ and reduced only slightly in the long period of the photocatalytic process. First-principles calculations reveal that the distorted Ni-1T′-MoS₂ with SV could generate favorable water adsorption energy (E_ad(H₂O)) and Gibbs free energy of hydrogen adsorption (∆G_H). This work exhibits a facile and promising pathway for synergistically regulating physical properties, electronic structure, or wettability based on the doping strategy for designing HER electrocatalysts.

Defect engineering is one of the effective strategies to optimize the physical and chemical properties of molybdenum disulfide (MoS₂) to improve catalytic hydrogen evolution reaction (HER) performance. Dislocations, as a typical defect structure, are worthy of further investigation due to the versatility and sophistication of structures and the influence of local strain effects on the catalytic performance. Herein, this study adopted a low-temperature hydrothermal synthesis strategy to introduce numerous dislocation-strained structures into the in-plane and out-of-plane of MoS₂ nanosheets. Superior HER catalytic activity of 5.85 mmol·g⁻¹·h⁻¹ under visible light was achieved based on the high-density dislocations and the corresponding strain field. This work paves a new pathway for improving the catalytic activity of MoS₂ via a dislocation-strained synergistic modulation strategy.