2LaCo0.7Fe0.3O3/N-doped carbon bifunctional electrocatalyst derived from g-C3N4 nanosheets for zinc-air battery. (10th May 2022)

• Record Type: Journal Article
• Authors: Liu, Haoquan; Ren, Xinghui; Bai, Haoyang; Qiao, Huici; Lu, Jinwei; Wang, Xuefei; Huang, Hao; Hu, Jie
• Is Part Of: Electrochimica acta. Volume 414(2022)
• Publication Date: 2022-05-10
• Subjects: Perovskite -- Electrocatalyst -- Zn-air battery -- N-doped carbon -- DFT calculation; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.140211
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: LCFO/xNC hybrids are prepared using CNNS as carbon and nitrogen source. The high dispersion of perovskite on the NC substrate exposes more active sites. 2LCFO/NC has high concentration of oxygen vacancies to promote the adsorption. The enhancement Co-O covalency is beneficial to the electrocatalytic process. The reduction of RDS free energy change accelerate the reaction process. Abstract: Perovskite oxides have been widely studied as one of the excellent bifunctional oxygen electrocatalysts (ORR: Oxygen Reduction Reaction, OER: Oxygen Evolution Reaction) due to its flexible crystal structure and low cost. Herein, 2LaCo0.7 Fe0.3 O3 /N-doped carbon is prepared by sol-gel method using g-C3 N4 nanosheets as carbon source and nitrogen source. The LaCo0.7 Fe0.3 O3 nanoparticles have excellent dispersibility on the N-doped carbon substrate and the composite material has higher oxygen vacancy concentration, showing enhanced bifunctional electrocatalytic activity (△ E =Ej=10, OER -E1/2, ORR =1.03 V) compared with the original LaCo0.7 Fe0.3 O3 (△ E = 1.12 V). Moreover, 2LaCo0.7 Fe0.3 O3 /N-doped carbon-based Zn-air battery presents excellent cycling stability (over 24 h) and high peak power density of 116 mW cm −2 . Density functional theory (DFT) calculations revealed the mechanism of improvement electrocatalytic activity of 2LaCo0.7 Fe0.3 O3 /N-doped carbon, which comes from the regulated electronic structure, including enhanced conductivity and the covalence of Co-O bond, reducing the free energy change of rate-determining step. This study provides a novel strategy for the design and prepare perovskite-type bifunctional electrocatalysts. Graphical abstract: Multi-factor optimization in 2LaCo0.7 Fe0.3 O3 /N-doped carbon, including high oxygen vacancy concentration, improved conductivity and the covalence Co-O bond, and reducing the free energy change of rate-determining step. Image, graphical abstract