Layered Double Hydroxide-Modified Electrodes for Gaseous Acetaldehyde Degradation at the Solid-Gas Interphase

Electrochemical application has been considered a promising technology in environmental remediation. However, the development of hydrocarbon ligand-free mediators for long-term operation still deserves further assessments. In this study, three different combinations (NiAl, CoAl, NiCo) of layered double hydroxide (LDH) electrodes were prepared using in situ and ex situ methods. These LDH electrodes were applied as solid electrocatalysts for gaseous acetaldehyde degradation using a membrane-divided flow-through electrolytic cell. In cyclic voltammetry analysis, the in situ prepared LDH-electrodes had high peak currents in high-valent redox couples (Ni^3+/2+Al³⁺, Co^3+/2+Al³⁺, and Ni^3+/2+Co^3+/2+) compared to low-valent redox couples (Ni^2+/1+Al³⁺, Co^2+/1+Al³⁺, and Ni^2+/1+Co^2+/1+). Due to the higher active surface area, the overall redox peak current was higher in the in situ prepared LDH electrode than the ex situ LDH electrode. During electrocatalytic degradation of acetaldehyde, the LDH electrodes containing cobalt ions had a higher mediated catalysis activity than the LDH containing nickel ions (NiAl-LDH). The Co³⁺ ions placed in the layered hydroxide synergistically mediate the electrons to degrade acetaldehyde at the solid-gas interface sustainably.