Turnovers drive supported metal nanoparticle catalyst surface reconstruction to kinetically trapped metastable structures

作者：Silvia Mariño, Yulan Han, Samji Samira, Ryan T. Berry, Michael Gordon, Anastassia N. Alexandrova, Phillip Christopher · 发表于：ChemRxiv · 年份：2026 · DOI：10.26434/chemrxiv.10001485/v1 · 被引用次数：1 · 研究领域：Catalytic Processes in Materials Science、Electrocatalysts for Energy Conversion、Catalysts for Methane Reforming

Catalytic reactions on supported metal catalysts often proceed at high adsorbate coverages that can induce structural changes to the catalyst as compared to the clean catalyst. Such restructuring is typically described within an equilibrium picture, where nanoparticle shapes, surface structures, and adsorbate coverages are assumed to find their thermodynamically preferred state. Here, we challenge this assumption and propose that under conditions of high adsorbate coverage and fast turnovers of surface species, common of many industrial catalytic processes, supported metal nanoparticle structures and adsorbate coverages can become kinetically trapped in metastable states. We studied the CO adsorptiondesorption quasi-equilibrium on a Pt/γ-Al2O3 catalyst as a model system via in-situ IR spectroscopy and chemisorption as a function of temperature (300-650 K), CO pressure (10-2-10-4 bar) and visible photon flux (0-2 W/cm 2 440 nm photons). The area of the IR feature associated with adsorbed CO increases as a function of temperature and the inclusion of photon flux, in stark contrast with expectations of decreasing CO coverage from thermodynamic models. Quantitative estimates of apparent dispersion, CO desorption rates, and the reversibility of IR changes support the hypothesis that when CO turnovers are faster than 2 the time scale of Pt atomic rearrangements to their equilibrium state, the catalyst is driven into a metastable state (Pt structure and CO coverage). Based on this a...