Development of Highly Active Bifunctional Electrocatalyst Using Co₃O₄ on Carbon Nanotubes for Oxygen Reduction and...

Replacement of precious platinum catalyst with efficient and cheap bifunctional alternatives would be significantly beneficial for electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and the application of these catalysts in fuel cells is highly crucial. Despite numerous studies on electrocatalysts, the development of bifunctional electrocatalysts with comparatively better activity and low cost remains a big challenge. In this paper, we report a nanomaterial consisting of nanocactus-shaped Co₃O₄ grown on carbon nanotubes (Co₃O₄/CNTs) and employed as a bifunctional electrocatalyst for the simultaneous catalysis on ORR, and OER. The Co₃O₄/CNTs exhibit superior catalytic activity toward ORR and OER with the smallest potential difference (0.72 V) between the [Formula: see text] (1.55 V) for OER and E_1/2 (0.83 V) for ORR. Thus, Co₃O₄/CNTs are promising high-performance and cost-effective bifunctional catalysts for ORR and OER because of their overall superior catalytic activity and stability compared with 20 wt% Pt/C and RuO₂, respectively. The superior catalytic activity arises from the unique nanocactus-like structure of Co₃O₄ and the synergetic effects of Co₃O₄ and CNTs.