Efficiently Enhanced Selectivity of Electrocatalyzing Ethanol to High Value-Added Acetaldehyde Through Tuning the Cobalt Valence State
Yintong Zhang, Junhao Wu, Tao Li, Haijin Li, Yongcai Zhang, Xinglong Wu, Yong Zhou, Zhigang Zou
Abstract
Using electrochemical oxidation of alcohols to substitute the oxygen evolution reaction is beneficial to reduce the energy consumption of hydrogen production. Converting alcohols into high value-added products with high efficiency and selectivity by designing a proper electrocatalyst is economical and has promising applications. In this work, two types of spinel cubic phase Co 3 O 4 with different contents of oxygen vacancies were obtained by annealing the same precursor in air and argon gas atmosphere, respectively. The results of X-ray photoelectron spectroscopy and in situ Raman spectra reveal that abundant Co 4+ sites were formed on the surface of Co 3 O 4 –air under the electrocatalysis condition, while main Co 3+ sites were formed on the surface of Co 3 O 4 –Ar. The electrocatalytic ethanol oxidation tests and density functional theory calculation reveal that the Co 4+ sites exhibit more proper adsorption energy to the O═*CCH 3 intermediate, which benefits the formation of high-value-added acetaldehyde products instead of common acetic acid products with a higher degree of oxidation. The Faradaic efficiency of the Co 3 O 4 –air catalyst to acetaldehyde achieves 60.02%, and the selectivity to acetaldehyde reaches 79.63% at an oxidation overpotential of 1.46 V. This work provides the possibility and guidance for electrochemical oxidation of alcohols into high value-added products.