Fluorine-Mediated Interfacial Microenvironment for Boosting pH-Universal CO₂ Reduction.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Efficient and stable carbon dioxide reduction reaction (CO2RR) to value-added chemicals is critical but hindered by complex gas-solid-liquid interfaces.
• The competitive hydrogen evolution reaction (HER) often reduces the selectivity and efficiency of CO2RR, especially at industrial current densities.
• Controlling the local microenvironment at the three-phase interface is key to optimizing CO2RR performance.

Purpose of the Study:

• To enhance the CO2RR performance of nickel (Ni) species by regulating the local microenvironment.
• To suppress the competing hydrogen evolution reaction (HER) for improved CO2RR selectivity and efficiency.
• To achieve high-performance CO2RR in a universal pH range at industrial current densities.

Main Methods:

• Introduction of highly electronegative fluorine (F) into nickel catalysts (Ni/FC) to modify the three-phase interface.
• Electrochemical characterization of CO2RR and HER performance in a broad pH range.
• In situ experiments and density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• The optimized Ni/FC catalyst achieved over 90% Faraday efficiencies for CO2 to CO conversion in pH-universal conditions.
• Ni/FC demonstrated stable operation at 200 mA cm⁻² for over 3000 hours, outperforming most reported CO2RR electrocatalysts.
• Fluorine introduction created a positive carbon center (Cδ+), inhibiting hydrogen adsorption and water dissociation, thus suppressing HER.

Conclusions:

• Regulating the local microenvironment of the three-phase interface by introducing electronegative elements is an effective strategy for boosting CO2RR.
• The fluorine-modified Ni/FC catalyst offers a promising solution for efficient and stable CO2 conversion to CO.
• This work provides a new perspective for designing advanced electrocatalysts by suppressing competitive HER.