[BMIM][BF4]-Functionalized ZIF-8 hybrids: Microenvironment modulation enabling ultrahigh CO selectivity in electrocatalytic CO2 reduction

The electrocatalytic reduction of CO 2 to CO represents an important approach for carbon resource utilization. However, most existing catalysts still suffer from low activity and poor selectivity. In this work, a novel “domain-confined interface” synergistic catalytic system was constructed by integrating ionic liquid [BMIM][BF 4 ] with zeolitic imidazolate framework-8 (ZIF-8) to enhance the CO 2 reduction reaction (CO 2 RR) performance. The high specific surface area and microporous structure of ZIF-8 provide an ideal platform for CO 2 adsorption and activation, while [BMIM][BF 4 ] improves the local microenvironment of the catalytic interface, thereby boosting the catalytic activity. Experimental results indicate that the incorporation of the ionic liquid significantly enhances the CO 2 RR performance of ZIF-8 at low potentials. The Faradaic efficiency for CO (FE CO ) increases from 38.98 % to 75.25 % at −0.8 V versus the reversible hydrogen electrode (RHE). Moreover, at the optimal potential of −1.2 V (vs. RHE), FE CO reaches 96 % and remains stable during an 8-hour durability test, outperforming most reported ZIF-8-based catalysts. This work may provide useful insights for the design of efficient CO 2 RR electrocatalysts.