Nanoparticle-Single-Atom Tandem Catalyst within a Metal-Organic Framework for Efficient Ethylene Electrosynthesis

Copper nanoparticles (Cu NPs) are effective catalysts for the electroreduction of CO₂ (ECO₂R) to multicarbon products but suffer from insufficient selectivity, aggregation, and deactivation. To address these challenges, we developed an in situ encapsulation strategy that engineers Cu NPs in a metal-organic framework (MOF) host from a simple one-pot hydrothermal synthesis, creating a selective and robust CO₂R catalyst. The key design is the introduction of Sn additives during synthesis, which later evolve into single atoms (SAs) that serve a dual function: modulating the growth of Cu NPs from 3.35 to 9 nm and acting as active sites for the conversion of CO₂ to CO. The locally generated CO then feeds adjacent Cu NPs, promoting subsequent C-C coupling via a tandem mechanism. The optimal catalyst, with a balanced Cu/Sn ratio, achieves a CO₂-to-C₂H₄ Faradaic efficiency (FE) of 64%. Combined theoretical simulations and in situ infrared spectroscopy further reveal that Sn SAs promote Cu NPs electron transfer, enriching the electron density at active sites. This stabilizes *CO intermediates and reduces the energy barriers for CO₂ activation and ensuing C-C coupling steps. This work presents a novel atomic- and nanoscale design strategy for advanced CO₂RR catalysts.