Towards high-performance electrocatalysts: Activity optimization strategy of 2D MXenes-based nanomaterials for water-splitting.

[Display omitted] • The underlying mechanism of MXenes-based materials is uncovered for water splitting. • The optimization strategy for high-efficiency MXenes-based materials is proposed. • An insight into the future direction of MXenes-based electrocatalysts is prospected. Water splitting has been considered as a sustainable and environmentally-friendly technique to realize green hydrogen production. However, the production of H 2 fuel is restricted by the sluggish kinetics and high overpotentials of the hydrogen evolution and oxygen evolution reactions. It is crucial to seek for high-efficiency electrocatalysts to boost the performance of water splitting. Among a great class of nanomaterials, MXenes-based nanomaterials can be utilized as excellent substrates to design novel materials due to their large specific surface area (SSA), fast electronic transmission, and excellent mechanical stability. However, the breakthroughs are at the experimental synthesis stage and lack all understanding of basic principles on catalytic mechanism, and then severely impede the development of high-efficiency electrocatalyst. Hence, some challenges still need to be clarified and resolved for further applications in electrocatalytic water splitting. In this review, the recent process on the synthesis routes, physical properties and performance improvement strategies for electrocatalytic water splitting of MXenes are summarized. We comprehensively summarize the electrocatalytic water splitting mechanism of MXenes both experimentally and theoretically. The in-depth discussion on structure–activity relationships and the basic understanding on electrocatalytic mechanisms of MXenes are also reviewed. At last, an insight into the future challenges, opportunities and further research directions of MXenes and related materials in the water-splitting application is prospected. This review offers a significant understanding for the design and optimization of high-efficiency MXenes-based electrocatalysts in water-splitting applications. [ABSTRACT FROM AUTHOR]