Elucidating the Role of Oxide–Oxide/Carbon Interfaces of CuO<sub><i>x</i></sub>–CeO<sub>2</sub>/C in Boosting Electrocatalytic Performance
Chiranjita Goswami, Yusuke Yamada, Е.В. Матус, И.З. Исмагилов, М. А. Керженцев, Pankaj Bharali
Abstract
Herein, we report the synthesis and bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of a CuOx–CeO2/C electrocatalyst (EC) with rich oxide–oxide and oxide–carbon interfaces. It not only demonstrates a smaller Tafel slope (65 mV dec–1) and higher limiting current density (−5.03 mA cm–2) but also exhibits an onset potential (−0.10 V vs Ag/AgCl) comparable to that of benchmark Pt/C. Besides undergoing the favorable direct four-electron ORR pathway, it unveils a loss of 23% of its initial current after 6 h of a stability test and a negative shift of 4 mV in the half-wave potential after the accelerated durability test compared to the corresponding current loss of 28% and negative shift of 20 mV for Pt/C. It also reveals remarkable OER activity in an alkaline medium with a low onset potential (0.20 V) and a smaller Tafel slope (177 mV dec–1). The bifunctional ORR/OER activity of CuOx–CeO2/C EC can be ascribed to the synergistic effects, its unique structure with enriched oxygen vacancies owing to the presence of Ce4+/Ce3+, robust oxide–oxide and oxide–carbon heterointerfaces, and homogeneous dispersion of oxides over the carbon bed, which facilitates faster electronic conduction.