A hierarchical Co3O4/CoS microbox heterostructure as a highly efficient bifunctional electrocatalyst for rechargeable Zn–air batteries?

Journal of Materials Chemistry A Pub Date: 2021-07-19 DOI: 10.1039/D1TA01912K

Abstract

Herein, we report the synthesis of a strongly coupled Co3O4/CoS microbox heterostructure, prepared through an annealing treatment with the subsequent hydrothermal sulfidation of a Co–Co Prussian blue analog (PBA) precursor. The unique 3D hierarchical architecture and potential synergies of Co3O4 and CoS provide benefits to the Co3O4/CoS heterostructure for both oxygen reduction and evolution reactions (ORR and OER). It displays comparable ORR catalytic activity (half-wave potential of 0.820 V) to state-of-the-art Pt/C but better durability and methanol tolerance. The Co3O4/CoS electrocatalyst also shows high OER activity with a relatively low overpotential (349 mV at 10 mA cm?2) and small Tafel slope (66.6 mV dec?1), compared to those of commercial RuO2 (366 mV at 10 mA cm?2 and 86.3 mV dec?1, respectively), making it a potential bifunctional electrocatalyst for both the ORR and the OER. Moreover, a rechargeable Zn–air battery with a Co3O4/CoS cathode shows a higher cell voltage (1.51 V), higher power density (168 mW cm?2 at 269 mA cm?2), and better cycling stability (up to 150 cycles) than the same battery with the state-of-the-art Pt/C + RuO2 catalyst. This PBA-based material with a strongly coupled interface between Co3O4 and CoS offers insights into the development of low-cost and highly efficient electrocatalysts for diverse energy-related applications.

Graphical abstract: A hierarchical Co3O4/CoS microbox heterostructure as a highly efficient bifunctional electrocatalyst for rechargeable Zn–air batteries
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