Lewis acid sites modulate local pH of Cu for efficient electrocatalytic CO2 reduction to C2+ products

Abstract

Electrocatalytic carbon dioxide reduction reaction (CO₂RR) offers a promising pathway to achieve carbon neutrality. For CO₂RR, alkaline electrolytes not only suppress the hydrogen evolution reaction (HER) but also facilitate the formation of multi-carbon (C₂₊) products. However, alkaline electrolytes react with CO₂ and continuously generate carbonates, which leads to poor carbon conversion and stability. Herein, CeO₂ enriched with Lewis acid sites was incorporated into Cu catalyst to modulate local pH near Cu and promote C₂₊ formation in neutral electrolyte. In situ pH detection measurements including Raman spectroscopy and rotating ring-disk electrode demonstrate the elevated local pH at the vicinity of Cu induced by the addition of Lewis acid sites during CO₂RR, while in situ spectroscopy combined with experiments design reveal the role of high local pH in promoting C₂₊ selectivity. Through this design for modulating local pH, CO₂ is converted into C₂₊ products with high Faradaic efficiency (FE_C2+) of 80.5 % at 750 mA cm⁻², outperforming most reported Cu-based electrocatalysts in neutral electrolyte flow cells. This work provides a feasible approach to regulate the local microenvironment at the catalyst-electrolyte interface and stabilize key intermediates to enhance the generation of C₂₊ products.