Abstract
The hydrogen evolution reaction (HER) is a pivotal process for sustainable hydrogen production, and two-dimensional (2D) materials have emerged as promising electrocatalysts due to their unique structural and electronic properties. However, their catalytic activity is often limited by the scarcity of active sites. Defect engineering offers a powerful strategy to modulate the electronic structure and create additional active sites, thereby enhancing HER performance. This review systematically examines recent advances in defect engineering of 2D materials for HER, focusing on transition metal dichalcogenides (TMDs), layered double hydroxides, and other 2D systems. We categorize defect types—including vacancies, dopants, grain boundaries, and edge sites—and discuss their effects on electronic properties, Gibbs free energy of hydrogen adsorption, and catalytic activity. Key synthesis methods such as chemical vapor deposition, plasma treatment, and wet-chemical approaches are evaluated. A meta-analysis of over 50 studies reveals that defect-rich MoS2 exhibits an average overpotential reduction of 120 mV at 10 mA cm−2 compared to pristine counterparts, with a Tafel slope decrease of 35 mV dec−1. We also highlight emerging strategies like moiré superlattice engineering and Janus structures. Challenges remain in precise control of defect type and density, as well as stability under operating conditions. Future directions include in situ characterization and machine learning-guided defect design. This work provides a comprehensive framework for understanding defect–property relationships and guides the rational design of high-performance HER electrocatalysts.
Keywords
defect engineering, two-dimensional materials, electrocatalysis, hydrogen evolution reaction, transition metal dichalcogenides, vacancy, active sites, Tafel slope