Dynamic Self-Optimization of PtNi Nanocatalysts Through the Concurrent Evolution of Active Sites and Interfacial Environment During Reaction.

Abstract

Heterogeneous catalysis is shifting from static material design to steering dynamic systems. Here, using the oxygen reduction reaction (ORR) over PtNi catalysts as a model system, we show that the leaching and structural reconstruction of PtNi alloys during the reaction do not degrade performance but actively drive the catalyst toward a superior state. Combining quasi-in situ transmission electron microscopy (TEM), quasi-in situ x-ray diffraction (XRD), in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and theoretical calculations, we decipher a potential-driven reconstruction process, initiated by Ni leaching and Pt dissolution-reposition, that transforms initial polyhedral core-shell structures into highly active nanocages. This yields a 2.3-fold enhancement in mass activity at 0.9 V vs. RHE through two synergistic factors. First, the newly formed porous structure increases the population of highly active, low-coordination Pt sites for O2 activation. Second, the restructured surface templates the interfacial water into a network featuring stronger symmetric hydrogen bonds, consistent with a more favorable interfacial environment for proton transfer. This concerted optimization of both the solid catalyst and the liquid environment during reaction process extends the static paradigm of catalyst design and introduces dynamic interfacial water engineering as a vital dimension for advancing electrocatalyst development.

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