Hybrid Co@Ni12P5/PPy microspheres with dual synergies for high performance oxygen evolution

Electrochemical water splitting could be an efficient alternative route for clean and renewable energy storage. However, widespread application of this technique is hindered by the high overpotential required for the sluggish anodic oxygen evolution reaction (OER). In this contribution, we report that novel N based conducting polymers exhibit excellent charge transfer properties with earth abundant transition metals. A strong interaction between Ni and N from polypyrrole (PPy) was identified via XPS, resulting in higher amounts of Ni delta++ sites at the interface. Electronegative N from PPy shell, covering Ni12P5 microspheres, interacts with Ni on the inner edge and electrodeposited Co on the outer edge, establishing a dual synergic effect. This hybrid catalyst, with Co-N and Ni-N active interfaces, demonstrates faster OER kinetics owing to improved electrophilicity towards hydroxyl ions. With dual M-N sites, Co@Ni12P5/PPy displays a low Tafel slope of 40 mV/dec and stability up to 7 h of electrochemical cycling. This work enables discovery of a new class of anode materials based on metal-PPy analogs for alkaline OER. (C) 2020 Elsevier Inc. All rights reserved.