Binary Transition Metal and Nitrogen Functionalised Silicon Oxycarbide Electrocatalysts for Zn–Air Battery Air Electrode Application

Abstract

The need for the wider adoption of next-generation energy storage systems due to the usage of renewable energy encourages the development of alternatives to the lithium-ion battery (LIB) technology. Rechargeable zinc–air battery (RZAB) could meet this objective as affordable, safe, and material abundant alternative if suitable non-Pt group metal (PGM) air electrode bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is developed. Herein, we investigate three binary transition metal (TM) combinations (Fe/Co, Fe/Mn, Fe/Cu) for the polymer-derived ceramics (PDCs)-based bifunctional catalyst fabrication. Dicyandiamide (DCDA) was used as a nitrogen source for the dual TM-containing PDC material modification. The highest electrocatalytic activity towards the ORR/OER in 0.1 and 1.0 M KOH was witnessed in the case of Fe/Co-containing material (Fe/Co-PDC-N, ORR/OER potential gap in 0.1 M KOH of 0.87 V), which was also the most promising non-PGM catalyst in the RZAB configuration. Fe/Co-PDC-N showed the maximum power density of 142 mW cm⁻², 46 h lifetime for 10 mA cm⁻² charge–discharge cycling and 97% depth of discharge (DoD). Comparative RZAB measurements were performed with the commercial Pt-Ru/C catalyst drawing attention to the performance enhancement implemented by the RZAB cell design modifications.