ABSTRACT

Electrocatalytic CO₂ reduction reaction (CO₂RR) has attracted considerable attention as a technology to recycle carbon dioxide (CO₂) into raw materials for chemicals using renewable energies. In this study, the electrocatalytic CO₂RR activity of Zn-Al layered double hydroxides (LDHs) was studied. Zn-Al LDHs loaded carbon sheets were prepared, and CO₂ RR was performed using CO₂-saturated KHCO₃ electrolyte to confirm the catalytic ability of Zn-Al LDH. Zn-Al LDHs intercalated with CO₃²⁻ anion were synthesized using the mixture of metal nitrates with the different molar ratio of Zn²⁺/Al³⁺ by the co-precipitation process, whose corresponding products were named as Zn₂Al₁ LDH, Zn₃Al₁ LDH, and Zn₄Al₁ LDH, respectively. Except for Zn₂Al₁ LDH, ZnO was observed to exist as an impurity. The synthesized Zn-Al LDHs exhibited the electrocatalytic CO₂RR activity for CO formation. In the case of the Zn₂Al₁ LDH, the current density of 15 mA cm⁻² was obtained with 77% selectivity for CO and 94% selectivity for (CO + H₂) at − 1.4 V vs. RHE. Furthermore, Zn₃Al₁ and Zn₄Al₁ LDHs showed a significant change relating to ZnO impurities in the XRD patterns and SEM images before and after the CO₂RR whereas Zn₂Al₁ LDH did not show it. These results indicate that Zn-Al LDH is promising as a CO₂RR electrocatalyst for CO formation.