Strong Metal–Support Interaction in Metal–Organic Framework (MOF)-Derived Multiphase TiO ₂ Supports for Durable Pt Catalysts in Acidic Hydrogen Evolution

Platinum-based electrocatalysts exhibit exceptional intrinsic activity toward the hydrogen evolution reaction (HER), but their practical deployment in water electrolysis is hindered by nanoparticle agglomeration, carbon-support degradation, and weak metal-support interaction (MSI). Here, porous TiO₂ supports with systematically tunable anatase-rutile composition were synthesized using MIL-125 (Ti) as a metal-organic framework (MOF) template, followed by controlled calcination and chemical reduction to anchor uniformly dispersed Pt nanoparticles. Precise phase engineering strengthened MSI, most notably in Pt/TiO₂-500, which displayed a distinct negative shift in Pt 4f (-0.7 eV) and a positive shift in Ti 2p (+0.5 eV), indicating strong interfacial electronic coupling. This optimized interaction reduced charge-transfer resistance, yielded overpotentials of 34 mV and 84 mV at 10 and 50 mA cm^-2, and produced a Tafel slope of 32.6 mV dec^-1, comparable to or better than many state-of-the-art TiO₂-supported Pt electrocatalysts. Pt/TiO₂-500 also preserved 96.5% of its activity after 2000 potential cycles and maintained stable operation for over 100 h at 10 mA cm^-2, confirming its structural and electrochemical robustness. These results demonstrate that phase-engineered MOF-derived TiO₂ significantly reinforces MSI, suppresses Pt agglomeration, and accelerates interfacial charge-transfer kinetics. This work establishes a generalizable strategy for designing durable and high-performance Pt-based electrocatalysts for sustainable hydrogen production.