Palladium nanoparticles supported by metal-organic frameworks derived FeNi3Cx nanorods as efficient oxygen reversible catalysts for rechargeable Zn-Air batteries

Abstract

The development of durable and high-efficiency bifunctional electrocatalysts for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is critical to boost the performance of rechargeable zinc-air batteries (RZABs). Herein, we report a general approach for fabricating FeNi3Cx-Pdy (x represents the indeterminate amount of carbon, y denotes the initial Pd mass loading percentage) nanorods using bimetallic metal-organic frameworks (MOFs) as sacrificial precursor. Among the series, FeNi3Cx-Pd-7% demonstrates the best performance as bifunctional oxygen catalyst. It exhibits a high electrocatalytic activity with an unexpectedly low overpotential of 288 mV for OER at 50 mA cm−2, which is far superior than the state-of-art RuO2 catalyst, and its performance for ORR also approximates to the benchmark Pt/C catalyst. When incorporated as air-cathode catalyst in a self-assembled RZAB, FeNi3Cx-Pd-7% exhibits a high power density of 234 mW cm−2, a large energy density of ∼967 W h kg−1, as well as a huge specific capacity of 772 mA h g−1 outperforming the noble-metal-based Pt/C + RuO2 catalyst. Additionally, FeNi3Cx-Pd-7% enables RZAB to obtain a long cycling life (over 900 cycles) with high efficiency and an overall overpotential of only 720 mV at 10 mA cm−2, presenting great potential for the commercial applications of RZABs.