AUTHOR=Zhang Yidan , Guo Youmin , Liu Tao , Feng Fuxu , Wang Chunchang , Hu Haibo , Wu Mingzai , Ni Meng , Shao Zongping TITLE=The Synergistic Effect Accelerates the Oxygen Reduction/Evolution Reaction in a Zn-Air Battery JOURNAL=Frontiers in Chemistry VOLUME=7 YEAR=2019 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00524 DOI=10.3389/fchem.2019.00524 ISSN=2296-2646 ABSTRACT=

Perovskite oxides are promising electrocatalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) due to their abundance and high intrinsic catalytic activity. Here we introduce Ag into Sm0.5Sr0.5CoO3−δ (SSC) to form a Ag-SSC catalyst by ultrasonication and apply it as the air electrode for a Zn-air battery. It finds that the introduction of Ag into SSC can transform the Ag-SSC into a good bifunctional electrocatalyst toward ORR as well as OER. For instance, a more active half-wave potential with a value of 0.76 V for ORR is obtained at 1,600 rpm, while the OER overpotential is 0.43 V at I = 10 mA cm−2. Further characterization demonstrates that the improved catalyst activity of the Ag-SSC can be assigned to the synergistic effect generated between the Ag and SSC phases. The Zn-air battery with the Ag-SSC as an electrode not only gives a same discharge-charge voltage gap (1.33 V) with that of commercial Pt/C (1.33 V) but also presents an equivalent current efficiency (45.7% for Ag-SSC and 45.3% for Pt/C) at 10 mA cm−2. Moreover, the stability for 110 cycles is better. This result indicates that the Ag-SSC catalyst shows promise for use as a bifunctional electrocatalyst toward OER and ORR.