Efficient electrocatalytic reduction of CO₂ to CO on highly dispersed Ag nanoparticles confined by Poly(ionic liquid)

Efficient electrocatalytic conversion of CO₂ to CO is a promising mode for CO₂ transformation driven by renewable electricity. Herein, varied poly(ionic liquid)-Ag (PIL-Ag) hybrids are facilely synthesized by impregnating chloride-based PIL with silver salts. The remarkable confinement effect of PIL on the patterns of in-situ formed highly dispersed Ag–Cl species leads to the corresponding complexes, clusters, and nanoparticles (NPs) in the inner domain, while their distribution is highly correlated to both microstructures of the PIL skeleton and silver salts launched. As a result, the highly dispersed imidazolium-pyridine-imidazolium tridentate sites at the PIL layer combined with a compatible supply rate of Ag⁺ cation enables the formation of abundant AgCl NPs in PIL-Cl@AgOAc-1.0, which provided a high CO selectivity of 96.8 % with a high partial current density of 207.0 mA cm⁻² at –0.91 V (vs RHE) in 1 M KOH. Besides, long-term electrolysis was conducted at 100 mA cm⁻² for 100 h with a slight decay of selectivity to ∼ 86 %. Further, despite the similar intrinsic activity of three Ag–Cl species, the patterns of Ag–Cl species, the number of active sites, and the mass transfer of reactants within the hybrids jointly determine the apparent electrocatalytic performance obtained at high rates.