Moving beyond Ti 2 C 3 T x MXene to Pt-Decorated TiO 2 @TiC Core-Shell via Pulsed Laser in Reshaping Modification for Accelerating Hydrogen Evolution Kinetics.

Phase engineering of nanocatalysts on specific facets is critical not only for enhancing catalytic activity but also for intensely understanding the impact of facet-based phase engineering on electrocatalytic reactions. In this study, we successfully reshaped a two-dimensional (2D) MXene (Ti 3 C 2 T x ) obtained by etching Ti 3 AlC 2 MAX via a pulsed laser irradiation in liquid (PLIL) process. We produced a TiO 2 @TiC core-shell structure in spheres with sizes of 200-350 nm, and then ∼2 nm ultrasmall Pt NPs were decorated on the surface of the TiO 2 @TiC core-shell using the single-step PLIL method. These advances allow for a significant increase in electrocatalytic hydrogen evolution reaction (HER) activity under visible light illumination. The effect of optimal Pt loading on PLIL time was identified, and the resulting Pt/TiO 2 @TiC/Pt-5 min sample demonstrated outstanding electrochemical and photoelectrochemical performance. The photoelectrochemical HER activity over Pt/TiO 2 @TiC/Pt-5 min catalyst exhibits a low overpotential of 48 mV at 10 mA/cm 2 and an ultralow Tafel slope of 54.03 mV/dec with excellent stability of over 50 h, which is hydrogen production activity even superior to that of the commercial Pt/C catalysts (55 mV, 62.45 mV/dec). This investigation not only serves as a potential for laser-dependent phase engineering but also provides a reliable strategy for the rational design and fabrication of highly effective nanocatalysts.