Electronic Regulation of Nickel Single Atoms by Confined Nickel Nanoparticles for Energy-Efficient CO₂ Electroreduction

Modulating the electronic structure of atomically dispersed active sites is promising to boost catalytic activity but is challenging to achieve. Here we show a cooperative Ni single-atom-on-nanoparticle catalyst (NiSA/NP) prepared via direct solid-state pyrolysis, where Ni nanoparticles donate electrons to Ni(i)−N−C sites via a network of carbon nanotubes, achieving a high CO current density of 346 mA cm⁻² at −0.5 V vs RHE in an alkaline flow cell. When coupled with a NiFe-based anode in a zero-gap membrane electrolyzer, the catalyst delivers an industrially relevant CO current density of 310 mA cm⁻² at a low cell voltage of −2.3 V, corresponding to an overall energy efficiency of 57 %. The superior CO₂ electroreduction performance is attributed to the enhanced adsorption of key intermediate COOH* on the electron-rich Ni single atoms, as well as a high density of active sites.