Enhanced electrocatalytic degradation of acid orange 7 by using double perovskite La2CoxNi1-xMnO6/nickel foam as the electro-Fenton cathodes
Ruijuan Zhang, Xinyu Li, Yanjun Yu, Weilin Guo
Abstract
Adequate generation of hydrogen peroxide and its subsequent activation into reactive oxygen species (ROS) play a crucial role in the catalytic efficiency of heterogeneous electro-Fenton for the degradation of contaminants. Herein, a series of La 2 NiMnO 6 double perovskite with Co doping (La 2 Co x Ni 1-x MnO 6 ) were prepared by a facile sol-gel technique and applied as catalysts in heterogeneous electro-Fenton system to removal acid orange 7 (AO7). Nickel foam was chosen as the supporting substrate for the catalyst owing to its excellent physical properties to accelerate the conversion of O 2 to H 2 O 2 . La 2 Co 0.5 Ni 0.5 MnO 6 achieved 90.22 % of AO7 decomposition rate at 120 min via the heterogeneous electro-Fenton system, which was a significant improvement over the catalytic efficiency of both only NF and La 2 NiMnO 6 electrodes. Further studies have shown that the introduction of Co could heighten the efficient redox recycling of Ni 2+ /Ni 3+ and Mn 3+ /Mn 4+ on the electrode surface, synergically facilitating the conversion of H 2 O 2 to OH. Meanwhile, the three redox pairs (Ni 2+ /Ni 3+ , Mn 3+ /Mn 4+ and Co 2+ /Co 3+ ) also stimulated the production of superoxide radicals ( O 2 − ), which was also not negligible in enhancing degradation. Finally, the possible pathway and mechanism of the degradation of AO7 were proposed. This work demonstrates that La 2 Co x Ni 1-x MnO 6 /NF has the potential to be a satisfactory electrode for decomposition of organic dyes in aqueous solution.