Hierarchical Ni–Fe layered double hydroxide/MnO2 sphere architecture as an efficient noble metal-free electrocatalyst for ethanol electro-oxidation in alkaline solution

Abstract

Ni–Fe layered double hydroxide (LDH) nanosheets and hierarchical Ni–Fe LDH@MnO₂ spheres are synthesized by a facile and cost-effective approach for highly efficient ethanol electro-oxidation. The LDH@MnO₂ microspheres display excellent catalytic activity and robust durability for ethanol electro-oxidation, compared with the Ni–Fe LDH nanosheets. According to the analyses for nitrogen adsorption isotherms and electrochemical impedance spectra (EIS), it is inferred that the performance enhancement could be attributed to the MnO₂ increasing the concentration of OH_ads species on the Ni–Fe LDH surface. These OH_ads can react with C_1ad intermediate species to produce CO₂ or water soluble products, releasing the active sites on LDH for further electrochemical reactions. Therefore, it is expected that an effective noble-metal free catalyst for ethanol electro-oxidation could be obtained by tailoring structure and properties of LDHs and their composites.