Mn-Doping-Induced Co<sub>3</sub>O<sub>4</sub> Structural Distortion and Facet Change for Enhanced Electro-Activation of O<sub>2</sub> toward Pollutants Removal
Min Sun, Sheng-Nan Tang, Zixu Chen, Lin‐Feng Zhai, Yuanhua Xia, Shaobin Wang
Abstract
Oxygen is a green oxidant for the oxidative removal of environmental pollutants. In this work, we employed Mn-doped Co 3 O 4 for electrocatalytic activation of O 2 and investigated the effects of structure and facet on catalysis. Co 3+ substitution by Mn 3+ /Mn 4+ leads to Co 3 O 4 structural distortion and a shift of preferentially exposed (311) to a more catalytically active (220) plane. Meanwhile, more vacancies are created due to the structural defects and charge imbalance between Co 3+ and Mn 4+ . Experimental and theoretical investigations suggest that Mn-doping facilitates adsorption of O 2 on the deficient (220) plane of Co 3 O 4 by triggering a thermodynamically more stable Mn 0.65 Co 2.35 O 4 -[O 2 ]* intermediate. Mn 0.65 Co 2.35 O 4 gives a turnover frequency value 9.5 times higher than that for pure Co 3 O 4 . The electrocatalytic wet air oxidation process with Mn 0.65 Co 2.35 O 4 shows a great energy-saving merit with specific energy consumptions as low as 2.2–5.0 kW h kg-TOC –1 in mineralizing phenolic compounds. This work opens up new opportunities for advancing air oxidation technology into more competitive processes.