Novel bi-functional electrocatalysts based on the electrochemical synthesized bimetallicmetal organic frameworks: Towards high energy advanced reversible zinc–air batteries

Abstract

Advanced zinc-air batteries (ZABs) are garnered renewed-attention as one of the most sustainable choices to power energy grids and electric vehicles. Yet, slow ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) kinetics demonstrate a limiting factor for energy conversion performance of high-tech ZABs. Hence the development of effective catalysts for ORR and OER at air electrode to remarkably reduce the polarization loss in metallic-air batteries that seriously prevents the rate capability, operating life and energy performance is very important. We illustrate the powerful ZABs with innovative electrochemical-synthesized benzene-1,3,5 tricarboxylate (BTC)metal–organic frameworks (MOFs) bi-functional oxygen electrocatalysts as compared to routine MOFs. Ni/Fe-BTC-MOF shows superior electrocatalytic activity (0.595 V) with half-wave potential (0.964 V) for ORR and over-potential (1.521@10 mA cm 2 ) for OER, outperforming commercialRuO2and Pt/C. Ni/Fe-BTC-MOF cathode represents a high open circuit potential (1.55 V), discharge peak power density (182 mW cm 2 ) and a large specific capacity (775 mAh g 1 at 10 mA cm 2 ) compared to the previous reported. Also Ni/Fe-BTC-MOF shows the excellent lifetimes for 594 h (65.80% round trip efficiency @10 mA cm 2 ) with 5264 cycles. These encouraging results demonstrate the great potential of these novel MOFs for marketable execution of rechargeable Zn-air batteries.