Three-dimensional interlinked Co3O4-CNTs hybrids as novel oxygen electrocatalyst

Abstract As the core of novel fuel cells and water electrolysis systems, the cost and performance for oxygen reduction reaction (ORR) and evolution reaction (OER) is strongly related with the electrocatalysts. Herein, we successfully synthesize a three-dimensional interlinked non-noble metal-based bifunctional oxygen electrocatalyst, which is composed of Co-based metal organic frames (ZIF-67) derived Co3O4 polyhedrons and carbon nanotubes (CNTs). For the introduction of CNTs, the electron transfer rate of the Co3O4 polyhedron was obviously enhanced. Due to the synergetic effect between the CNTs and Co3O4 polyhedron, the as-synthesized Co3O4-CNTs hybrids displayed excellent electro-activity for ORR and OER. When served as ORR electrocatalyst, low onset potential (0.89 V), high half-wave potential (0.76 V) vs the reversible hydrogen electrode (RHE) and limiting current density (−6.28 mA cm−2) were obtained in O2-saturated 0.1 M KOH solution. In addition, when used for OER, only low overpotential of 370 mV was needed for yielding 10 mA cm−2 current density with 87 mV dec−1 of Tafel slope in 1 M KOH solution. What's more, the obtained Co3O4-CNTs hybrids also exhibited superior stability, implying its potential application possibility for novel energy-storage and transformation systems as electrode materials.