Cation-π interactions at the Cu-HHTP/MXene hybrid interface for efficient electrocatalytic CO₂ reduction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Two-dimensional (2D) conductive substrates enhance electrocatalyst stability and electron transfer kinetics.
• Metal-organic frameworks (MOFs) and MXenes are promising materials for electrocatalysis.
• Understanding interfacial interactions is crucial for optimizing catalytic performance.

Purpose of the Study:

• To engineer stable and efficient electrocatalysts for CO2 electroreduction by integrating Cu-HHTP with functionalized MXenes.
• To investigate the role of ion-π interactions in interfacial contact, electron transfer, and catalytic activity.
• To enhance CO2-to-CH4 conversion efficiency and catalyst durability.

Main Methods:

• Synthesis of Cu-HHTP/MXene hybrids (C/MXF, C/MXN, C/MXO) via ion-π interactions.
• Characterization using FT-IR, Raman, BET, microcalorimetry, and electrochemical analyses.
• Evaluation of CO2 electroreduction performance, including Faradaic efficiency and stability.

Main Results:

• C/MXN, with strong cation-π interactions, exhibited superior interfacial contact and electron transfer compared to C/MXO and C/MXF.
• NH2-functionalized C/MXN showed enhanced proton conductivity (1.59 × 10⁻² S·cm⁻¹) and a low activation energy (0.144 eV).
• C/MXN achieved a high Faradaic efficiency of 56% for CO2-to-CH4 conversion at -1.0 V vs. RHE, a ~7-fold improvement over pure Cu-HHTP, with excellent long-term stability.

Conclusions:

• Molecular interface engineering via ion-π interactions is a viable strategy for developing high-performance electrocatalysts.
• The NH2-functionalized Cu-HHTP/MXene hybrid (C/MXN) demonstrates significant potential for efficient and stable CO2 electroreduction.
• This work provides insights into designing structurally robust and electron-transporting electrocatalysts for energy conversion applications.