Improved OER performance of Co3O4/N-CNTs derived from newly designed ZIF-67/PPy NTs composite

In recent years, a noticeable shifting from conventional fossil fuels to renewable energy based systems has embarked electrochemical splitting of water as the most promising way to produce clean energy of hydrogen. Generally, the lack of active and stable electrocatalysts for oxygen evolution reaction (OER) limits the practicability of water splitting as a renewable source of energy. In this work, interconnected 3D structure of cobalt oxides nanoparticles (Co3O4 NPs) derived from ZIF-67 with nitrogen-doped carbon nanotubes (N-CNTs) of polypyrrole (PPy) origin is successfully synthesized as OER electrocatalysts. Impressively, the highly conductive N-CNTs that run through the Co3O4 NPs not only endow the resulting product Co3O4/N-CNTs with large active surface area and enhanced charge transfer between Co3O4 NPs, but also prevent Co3O4 NPs from aggregation. As a result, the as-synthesized Co3O4/N-CNTs electrocatalyst exhibits outstanding OER activity with a low onset potential of ~1.37 V (vs RHE), overpotential of only 200 mV to attain a stable current density of 10 mA cm−2 in basic media and very small Tafel slope of 40 mV dec−1. Moreover, the enhanced nitrogen-content also improves the OER kinetics by proficient charge transfer. The superb electrocatalytic performance and higher stability make the Co3O4/N-CNTs a proficient non-precious electrocatalyst for the OER.