Improving the Performance of Zn-Air Batteries with N-Doped Electroexfoliated Graphene

The constantly growing demand for active, durable, and low-cost electrocatalysts usable in energy storage devices, such as supercapacitors or electrodes in metal-air batteries, has triggered the rapid development of heteroatom-doped carbon materials, which would, among other things, exhibit high catalytic activity in the oxygen reduction reaction (ORR). In this article, a method of synthesizing nitrogen-doped graphene is proposed. Few-layered graphene sheets (FL-graphene) were prepared by electrochemical exfoliation of commercial graphite in a Na₂SO₄ electrolyte with added calcium carbonate as a separator of newly-exfoliated FL-graphene sheets. Exfoliated FL-graphene was impregnated with a suspension of green algae used as a nitrogen carrier. Impregnated FL-graphene was carbonized at a high temperature under the flow of nitrogen. The N-doped FL-graphene was characterized through instrumental methods: high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Electrochemical performance was determined using cyclic voltamperometry and linear sweep voltamperometry to check catalytic activity in ORR. The N-doped electroexfoliated FL-graphene obeyed the four-electron transfer pathways, leading us to further test these materials as electrode components in rechargeable zinc-air batteries. The obtained results for Zn-air batteries are very important for future development of industry, because the proposed graphene electrode materials do not contain any heavy and noble metals in their composition.