Tailoring the Catalytic Microenvironment of Cu₂O with SiO₂ to Enhance C₂₊ Product Selectivity in CO₂ Electroreduction

Abstract

Achieving high activity and selectivity of multicarbon products in the CO2 reduction reaction (CO2RR) on Cu-based electrocatalysts remains challenging due to the limited concentration of local OH–, sluggish CO2 diffusion, and competitive hydrogen evolution reaction. Herein, we report aerophilic nanocomposites of hydrophobic SiO2 aerosol and Cu2O nanocubes to tailor the microenvironment for enhancing CO2 electroreduction in 0.1 M KHCO3 aqueous electrolyte. Combined in situ infrared analysis, molecular dynamics simulations, and density functional theory calculations reveal that the composite Cu2O/SiO2 enriches the local hydroxyl by blocking the reaction between OH– and HCO3 –, accelerates CO2 diffusion coefficient (from 2.67 × 10–10 to 8.46 × 10–10 m2 s–1), and renders a lower dissociation energy of H2O than bicarbonate (0.49 vs 1.24 eV on Cu2O (111)) as compared to neat Cu2O. Consequently, Cu2O/SiO2 promotes the formation of C2+ products (Faradaic efficiency FEC2+ from 52.4 to 75.6%) and suppresses hydrogen generation (FEH2 from 30.0 to 9.6%) at −1.2 V versus reversible hydrogen electrode. The results provide insight into the selectivity improvement of CO2RR electrocatalysis by regulating the local microenvironment of alkalinity, H2O transportation, and CO2 permeability.

Highly efficient hydrogen production and selective CO2 reduction by the C3N5 photocatalyst using only visible light

“…CO 2 dissolved in water is known to exist in the form of CO 2 (aq), carbonic acid (H 2 CO 3 ), and carbonate ions (HCO 3 − ). 52 CO 2 + H 2 O ⇄ CO 2 (aq) + H 2 CO 3 ⇄ H + + HCO 3 − …”

Electronic modulation of a single-atom-based tandem catalyst boosts CO2 photoreduction to ethanol

“…Various strategies, including morphology control, dopant modification, and defect engineering, have been developed to modify the binding affinity and enrich the reaction intermediates, thereby enhancing the efficiency of Cu-based catalysts for CO 2 reduction to C 2+ products. 22,28–32 One particularly attractive approach involves the construction of tandem catalysts combining Cu-based materials with other CO 2 -active materials. This strategy addresses the complexity of the C 2+ product pathway, where one active site generates high-coverage *CO, while the other site promotes C–C coupling.…”

Recent Advances in Electrochemical CO2‐to‐Multicarbon Conversion: From Fundamentals to Industrialization

“…[ 32 ] But the past overviews only focused on the conventional optimizing strategies for eCO 2 ‐to‐multicarbon conversion, failing to offer novel insights to the following interdisciplinary design of both catalysts and electrolytic systems. [ 33–35 ]…”