Steering CO₂ Electroreduction to C₂₊ Products via Enhancing Localized CO Coverage and Local Pressure in Conical Cavity

The electrochemical carbon dioxide (CO2) reduction reaction (CO2RR) involves a multistep proton-coupled electron transfer (PCET) process that generates a variety of intermediates, making it challenging to transform them into target products with high activity and selectivity. Here, a catalyst featuring a nanosheet-stacked sphere structure with numerous open and deep conical cavities (OD-CCs) is reported. Under the guidance of the finite-element method (FEM) simulations and theoretical analysis, it is shown that exerting control over the confinement space results in diffusion limitation of the carbon intermediates, thereby increasing local pressure and subsequently enhancing localized *CO coverage for dimerization. The nanocavities exhibit a structure-driven shift in selectivity of multicarbon (C2+) product from 41.8% to 81.7% during the CO2RR process.