Interface-Engineered MXene/TMD Heterostructures for Efficient Hydrogen Evolution: Progress, DFT-Guided Mechanisms, and Perspectives

The hydrogen evolution reaction (HER) requires efficient, durable, and earth-abundant electrocatalysts to reduce reliance on platinum-group metals. MXene/transition-metal dichalcogenide (TMD) heterostructures offer a promising platform by combining the abundant, tunable catalytic sites of TMDs with the high electrical conductivity, hydrophilicity, and versatile surface chemistry of MXenes. This review critically examines recent advances in the synthesis, interfacial engineering, and HER performance of MXene/TMD heterostructures, with particular emphasis on how interfacial interactions govern catalytic behavior. The roles of phase engineering, defect and heteroatom incorporation, surface terminations, and heterointerface construction are discussed in relation to interfacial charge redistribution, electronic-structure modulation, hydrogen adsorption energetics, active-site accessibility, and reaction kinetics. Experimental HER performance across representative MXene/TMD systems is compared to establish structure-interface-performance relationships and identify the origins of enhanced activity and stability. Particular attention is given to density functional theory (DFT) as a mechanistic tool for resolving heterostructure stability, interfacial charge transfer, electronic structure, and hydrogen adsorption free energy (ΔGH*). The review also assesses limitations in current computational descriptions of electrocatalytic interfaces, including solvent and electrolyte effects, potential-dependent surface charging, dynamic surface reconstruction, and the accuracy of commonly used exchange-correlation functionals. By integrating experimental observations with theoretical insights, this review identifies interfacial electronic coupling and local active-site chemistry as central determinants of HER performance, while highlighting oxidation stability, interfacial reproducibility, realistic electrochemical modeling, and scalable fabrication as persistent challenges. Finally, future directions combining controlled interfacial synthesis, operando characterization, and advanced constant-potential and solvent-inclusive simulations are proposed to accelerate the development of efficient and durable MXene/TMD electrocatalysts for green hydrogen production.