Hydrophobic Ionic Liquid Engineering for Reversing CO Intermediate Configuration toward Ampere-Level CO₂ Electroreduction to C₂₊ Products

Abstract

Hydrophobic ionic liquid (HIL) engineering on the catalyst surface represents a simple yet potent direction for optimizing the CO₂ electroreduction performance. However, the pivotal role of HIL engineering at an industrial current density is still ambiguous due to limited and conflicting research findings. Herein, HIL-engineered oxide-derived Cu porous nanoparticles with electron-delocalized groups and a specific ultramicropore structure are first constructed to facilitate CO₂-to-C₂₊ electroreduction at ampere-level current densities. The uniformly decorated HIL is innovatively demonstrated by positron annihilation lifetime spectroscopy, which offers unparalleled advantages in ultramicropore characterization. Bader charge-dependent performance analyses and theoretical calculations disclose that the N atoms in the HIL lower the adsorption energy of CO on the atop site from -0.38 to -1.42 eV through electron donation, which inverts the most stable adsorption site and favors the energy-efficient dimerization of atop-bound CO. Operando Raman spectra and in situ attenuated total reflection-surface enhanced infrared absorption spectroscopy indicate that the adhered HIL increases *CO coverage and alters the *CO adsorption configuration to an atop-bound state with an abundant high-frequency band. Furthermore, staircase potential electrochemical impedance spectroscopy unravels the specific arrangement structure of HIL enlarges the electrochemical surface charge by about 1.5 times, thereby accelerating CO₂ electroreduction. As a result, the HIL-engineered oxide-derived Cu porous nanoparticles achieve a prominent C₂₊ productivity with a Faradaic efficiency of 85.1% and a formation rate up to 2512 μmol h^-1 cm^-2, outperforming most reported Cu-based electrocatalysts.