Surface-functionalized three-dimensional MXene supports to boost the hydrogen evolution activity of Pt catalysts in alkaline media.

Alkaline water electrolysis is the most promising technology for green-hydrogen production, which is considered a cornerstone of carbon-neutral energy society. In the development of functional catalysts able to overcome the sluggish kinetics of the alkaline hydrogen evolution reaction (HER), MXenes emerge as attractive support candidates with distinctive hydrophilicity, high conductivity, and high (electro)chemical stability. Herein, we assess the promise of three-dimensionally interconnected Ti3C2Tx MXenes with distinct surface terminations (-O, -OH, and -F) as efficient support materials for Pt-loaded alkaline HER catalysts. In particular, our OH-functionalized Pt/Ti₃C₂(OH)x shows the highest HER activity (30 mV dec^-1), unlocking a competitive performance against the Pt/C reference (61 mV dec^-1) and benchmark literature reports. The outstanding performance is ascribed to the cooperative effects of the extended MXene surface area and established interactions between Pt and Ti(OH)x surface centers. In parallel, the oxophilic nature of Ti3C2(OH)x facilitates Pt dispersion, presumably playing a key role in the extended catalytic stability here reported. The superior activity is further substantiated by density functional theory calculations, with the modeled Pt/Ti₃C₂(OH)₂ unveiling a significantly higher onset potential and the weakest hydrogen binding energy over supported Pt nanoparticles (-2.51 eV) against both -O (-2.72 eV) and -F (-3.15 eV) functionalized counterparts. [ABSTRACT FROM AUTHOR]