Heteroatom Doping, Defect Engineering, and Stability of Transition Metal Diselenides for Electrocatalytic Water Splitting.

Designing stable and efficient catalysts for water electrolysis has been a crucial challenge in developing technologies for the sustainable production of hydrogen. So far, various metal-based nanomaterials have been reported as promising electrocatalysts for driving the water-splitting reaction. Among them, transition metal diselenides (TMDSes) have garnered significant attention owing to their unique layered and non-layered structure, tunable electronic properties, and intrinsic catalytic activity. However, their large-scale application is often limited by issues such as a scarcity of active sites and insufficient long-term stability under harsh electrochemical conditions. Consequently, various strategies have been implemented to overcome these drawbacks as well as enhance the overall catalytic efficiency. Mono- or multi-heteroatom doping can effectively modulate the electronic structure and improve charge transfer and adsorption energies. Additionally, the introduction of certain defects further increases active sites and facilitates charge transport. Despite these advancements, long-term stability remains a critical concern due to issues like leaching and structural degradation. This mini-review discusses the effect of doping and defect engineering on TMDSes for electrocatalytic water splitting. Additionally, recent and emerging approaches to improve stability have been discussed that will offer insights into designing robust electrocatalysts for water splitting.