Cobalt-nickel alloys supported on Ti4O7 and embedded in N, S doped carbon nanofibers as an efficient and stable bifunctional catalyst for Zn-air batteries.

Abstract

Transition metal catalysts for replacing noble metals have been extensively studied, but the deficiencies in intrinsic activity and stability limit their application in electrocatalysis. Here, we present CoNi alloy nanoparticles loaded on Ti4O7 supports and embedded in N, S doped carbon nanofibers by electrospinning method. The prepared CoNi/Ti4O7@NS-CNFs exhibits satisfactory ORR and OER activities with a low potential gap of 0.664V and shows a high stability over long periods of testing, which are superior to most of the transition metal catalysts reported so far. Accordingly, the Zn-air battery constructed with the prepared catalyst demonstrates a maximum power density of 165.7 mW cm-2 and a specific capacity of 788.4mAh gZn-1 (1.61 and 1.14 times higher than that of Pt/C+IrO2, respectively). The addition of S element and corrosion-resistant Ti4O7 plays a significant part in the morphology and activity of the prepared catalyst, which optimizes the distribution and electronic structure of active centers, and improves the stability of the catalyst. This effort provides a possible approach to exploring the efficient performance of the other transition metals.