(558i) In Situ Formed Pt3Ti Nanoparticles on Two-Dimensional Transition Metal Carbide (MXene) As Efficient Catalysts for Hydrogen Evolution Reaction

Designing efficient catalysts delivering high current density at low overpotential for hydrogen evolution reaction (HER) is urgently needed for its practical application. Herein we report platinum alloyed with the titanium from the surface of Ti₃C₂T_x MXenes to form Pt₃Ti intermetallic compounds (IMCs) via in situ co-reduction. In situ X-ray absorption spectroscopy (XAS) indicates that compositions of the formed alloys are temperature dependent, and the catalyst reduced at 550 ºC (Pt₃Ti/Mxene-550) exhibits superior and stable HER performance in acidic media due to the synergistic effect between Pt₃Ti intermetallic nanoparticles (iNPs) and the MXene support. Pt₃Ti/Mxene-550 catalyst outperforms the commercial Pt/Vulcan and many other reported catalysts with a small overpotential of 32.7 mV at a large current of 10 mA and low Tafel slope of 32.3 mV dec^-1. Moreover, the disparity of their overpotentials increases with the current, reaching 100 mV at 40 mA, capable of efficiently generating more hydrogen at less electrical energy consumption. Density functional theory calculations suggest that the Pt₃Ti shows weaker *H binding than Pt on (111) and (100) surfaces, while (110) termination has too exergonic *H adsorption for both, thus not active in the low overpotential region. This work demonstrates the potential of MXenes as platforms for the rational design of electrocatalysts and may spur future research for other MXene supported metal catalysts over a wide range of electrocatalytic reactions.