Copper-based pyridine complex catalyst for enhanced C2+ selectivity of CO2 electroreduction

Abstract

The electrochemical carbon dioxide reduction reaction (ECO₂RR) is an effective method for converting CO₂ into value-added chemicals, preventing global warming. The use of Cu-based catalysts for ECO₂RR is widespread because of its inexpensiveness, although they display low selectivity for C2+ due to the hydrogen evolution reaction (HER). Accordingly, we utilize the coordination of Cu²⁺ with pyridine and its derivatives to synthesize CuL₂Cl₂ (L = pyridine, 4-PP, 4-BP), thereby increasing the number of CO₂ adsorption sites for selective HER suppression. This strategy achieves a Faradaic efficiency of C2+ products (FE_C2+) of 55% at a voltage of −1.6 V vs. RHE in a flow cell, while Faradaic efficiency (Fe_H2) is reduced to 18%. X-ray photoelectron spectroscopy (XPS) analysis reveals the features of CO₂ adsorption, where the appearance of new bands confirms that pyridyl and phenyl can provide extra adsorption sites. The electroreduction process was monitored by in situ FTIR, by observing *COOH, *OCCOH etc. intermediates, disclosing the possible reaction path. This research opens a new perspective in the area of catalysis.