Titanium Architectures for Durable Water Electrolysis: From MXenes and Magnéli Phases to Single-Atom Catalysts

Abstract

The urgent transition toward a carbon-neutral energy economy positions water electrolysis as a cornerstone for sustainable “green hydrogen” production. While noble-metal catalysts define current benchmarks, their prohibitive costs and scarcity necessitate the development of robust, Earth-abundant alternatives. This review provides a comprehensive analysis of advanced titanium (Ti)-based architectures—specifically 2D MXenes, Magnéli phase suboxides (TinO2n−1), and single-atom catalysts (SACs)—as transformative platforms for hydrogen and oxygen evolution reactions (HER/OER). We examine the synergistic effects of MXenes, where metallic conductivity and tunable surface terminations (Tx) optimize hydrogen adsorption energetics. Simultaneously, we highlight exceptional electrochemical stability and strong metal–support interactions (SMSI) of Magnéli phases, which effectively circumvent the “universal scaling relationship” bottlenecks in OER. Furthermore, we emphasize the integration of SACs on these Ti-based supports, where engineering the local coordination environment maximizes atom utilization and intrinsically boosts catalytic activity. A strategic emphasis is placed on direct seawater electrolysis, highlighting the “chlorophobic” and self-healing properties of Ti-interfaces that ensure long term durability against chloride corrosion and mineral scaling. By integrating AI-driven discovery and field-scale engineering perspectives, this review provides a strategic roadmap for designing high-performance, non-noble metal-based systems for industrial-scale energy conversion, offering a viable solution to the long-standing stability-activity trade-off in extreme environments.