Confining High-Entropy Alloys within MOF-Derived Architectures: A Dual-Site Strategy Boosting Photothermal CO 2 Methanation

Abstract

High-entropy alloy (HEA) offer immense potential for catalytic transformations, yet they suffer from severe sintering and limited active site accessibility due to their typically dense architectures. Herein, we present a facile molten salt-assisted pyrolysis strategy to confine quinary CoNiCuPtPd HEA nanoparticles within a metal-organic framework (MOF)-derived support. By using UiO-66-NH2 as a precursor, the introduced amino groups are transformed into pyridinic nitrogen sites during pyrolysis, which, along with the abundant oxygen vacancies generated in the ZrO2 phase, creates a robust porous support UNH-730. Comprehensive characterizations (XPS, H2-TPR) confirm that the pyridinic N sites strongly anchor the metal species, facilitating the formation of homogeneously dispersed HEA nanoparticles (~15 nm) and preventing agglomeration. In-situ DRIFTS and catalytic evaluation reveal a synergistic mechanism: basic N sites and oxygen vacancies significantly enhance CO2 adsorption/activation, while the HEA sites promote H2 dissociation. Crucially, we demonstrate that light irradiation functions purely as a thermal source rather than triggering photogenerated electron-hole pairs. Consequently, the optimal CoNiCuPtPd@UNH-730 catalyst delivers a remarkable CH4 of 228.36 mmol g-1 h-1 with 77.8% selectivity at 550 °C under photothermal conditions substantially outperforming the ligand-free counterpart. This work establishes a novel paradigm for stabilizing multi-metal HEAs on functionalized porous carbon/oxide composites for energy conversion applications. Keywords: High-entropy materials; MOF-derived porous materials; dual-site strategy; Photothermal CO2 methanation