Optimized Electronic Configuration to Improve the Surface Absorption and Bulk Conductivity for Enhanced Oxygen Evolution Reaction

Authors

Xiaoning Li, University of WollongongFollow
Yanhua Sun, University of WollongongFollow
Qingmei Wu, University of Science and Technology of China
Huan Liu, Beijing University of Chemical Technology
Wen Gu, University of Science and Technology of China
Xiaolin Wang, University of WollongongFollow
Zhenxiang Cheng, University of WollongongFollow
Zhengping Fu, University of Science and Technology of China
Yalin Lu, University of Science and Technology of China

RIS ID

133597

Publication Details

Li, X., Sun, Y., Wu, Q., Liu, H., Gu, W., Wang, X., Cheng, Z., Fu, Z. & Lu, Y. (2019). Optimized Electronic Configuration to Improve the Surface Absorption and Bulk Conductivity for Enhanced Oxygen Evolution Reaction. Journal of the American Chemical Society, 141 (7), 3121-3128.

Abstract

The composition and structure are crucial for stabilizing an appropriate electronic configuration (unit e g electron for example) in high-efficiency electrocatalysts for the oxygen evolution reaction (OER). Here, an excellent platform to investigate the roles of the composition and structure in tuning the electron configuration for higher OER efficiency is provided by layered perovskite oxides with subtle variations of composition and structure (doping with 0%, 50%, and 100% cobalt in the Bi 7 Fe 3 Ti 3 O 21 ). The crystal structures were analyzed by X-ray diffraction refinement, and the electronic structures were calculated based on X-ray absorption spectroscopy and magnetization vs temperature plots according to the Curie-Weiss law. The results indicate that the elongation of oxygen octahedra along the c-axis in layered perovskite could stabilize Co ions in the intermediate spin (IS) (t 2g ) 5 (e g ) 1 state, resulting in dramatically enhanced electronic conductivity and absorption capacity. Subsequently, the OER efficiency of sample with 100% Co was found to be (incredibly) 100 times higher than that of the sample with 0% Co, with the current density increased from 0.13 to 43 mA/cm 2 (1.8 V vs reversible hydrogen electrode); the Tafel slope was reduced from 656 to 87 mV/dec; and double-layer capacity enhanced from 174 to 4193 μF/cm 2 . This work reveals that both the composition and structure should be taken into account to stabilize a suitable electronic structure such as IS Co ions with moderate absorption and benign electronic conductivity for high-efficiency catalysis of the OER.