Superhydrophobicity-enabled triphase interfacial microenvironment for high-temperature CO₂-to-formate electrocatalysis

Abstract

Thermal intensification of CO₂ electroreduction to the key feedstock formate is thermodynamically favorable; however, its practical utility is often compromised by solubility-driven CO₂ depletion and parasitic hydrogen evolution. Here, we develop a solid-liquid-gas triphase boundary (TPB) to circumvent this limitation. This architecture decouples the CO₂ supply from bulk solubility constraints, ensuring reactant availability under thermal activation. Electrochemical evaluation demonstrates that the TPB electrode maintains a Faradaic efficiency exceeding 80% at high temperature, along with a significant increase in formate production rate. Kinetic analyses reveal a distinct mechanistic divergence, showing that the TPB enhances turnover frequency (TOF) by 36% at 50 °C relative to 20 °C, whereas the conventional biphasic system suffers a 70% TOF decline. Mechanistic simulations indicate that the TPB sustains near-saturated interfacial CO₂ concentrations while facilitating rapid formate expulsion at elevated temperatures, thereby preventing product accumulation. This work presents a viable strategy for thermally intensified electrocatalysis by integrating material superhydrophobicity with thermal kinetics.

Keywords

CO₂ electroreduction / formate production / thermal intensification / triphase interface / mathematical modeling

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