N-Coordinated cobalt single atom-integrated electrospun nanofibers for an efficient oxygen evolution reaction

Abstract

The use of metal single-atom catalysts (SACs) has recently received a lot of attention for achieving an efficient oxygen evolution reaction (OER) in water splitting because of their unique catalytic properties due to unsaturated active sites with maximum atom utilization efficacy. However, designing architectural structures with specific coordination sites to avoid metal cluster formation and stabilization of SACs on a conductive support to overcome the inhomogeneous and slow transportation of ions/molecules is quite challenging. Thus, to overcome this challenge, herein, we report the fabrication of a N-coordinated cobalt SAC (NC-Co-SAC) on a carbon matrix derived from a predesigned bimetallic Zn/Co zeolitic imidazole framework (BM-ZIF). The fabricated NC-Co-SAC was then integrated at the surface of highly conductive cellulose acetate-polyaniline (CP) electrospun nanofibers and was evaluated in terms of its OER efficacy in water splitting. Surprisingly, the designed novel NC-Co-SAC@CP electrospun nanofibers offer lowest overpotential of 320 mV at 10 mA cm⁻² in 1 M KOH and a Tafel slope of 59 mV dec⁻¹ even much better than those of the commercial IrO₂ and RuO₂ and most reported non-precious metal catalysts. Additionally, the designed electrode demonstrated exceptional chemical stability, thus opening up more avenues for further exploring efficient noble metal free water splitting electrocatalysts for sustainable energy conversion.