3D Co-N-doped hollow carbon spheres as excellent bifunctional electrocatalysts for oxygen reduction reaction and oxygen evolution reaction

•Straightforward synthesis of new Co-N-doped carbon-based (Co-N@HCS) hollow nanospherical structures.•Co-N@HCS exhibits high OER and ORR electrocatalytic performance methanol tolerance and stability.•Excellent properties of Co-N@HCS are attributed to high surface area and 3D hollow architecture.

Non-precious materials have been considered as promising bifunctional catalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In the present work, a three dimensional (3D) Co-N co-doped hollow carbon sphere (HCS) electrocatalyst is synthesized at room temperature by the aid of a facile preparation method.The as obtained Co-N co-doped catalyst exhibits excellent catalytic activity towards both ORR and OER due to its high surface area and to 3D hollow architecture. For the ORR, the catalyst shows more positive onset-potential (of ∼0.962 V vs. RHE) and larger diffusion limiting current density (5.55 mA cm−2) compared with benchmark Pt/C catalyst in alkaline medium. Moreover, the as synthesized catalyst exhibits low potential (1.720 V vs. RHE) at the current density of 10 mA cm−2 and small Tafel slope (81 mV dec−1) for OER. In addition, the catalyst exhibits remarkable methanol tolerance and good long-term stability under working conditions. This strategy provides a facile and effective method for the preparation of non-noble metal catalysts with 3D hollow structure for energy conversion and storage applications.

Graphical abstractStraightforward synthesized Co-N-doped carbon-based hollow nanospheres exhibit high performance for both OER and ORR due to their high surface area and 3D hollow architecture.Download high-res image (252KB)Download full-size image