Bimetallic Organic Framework-Decorated Leaf-like 2D Nanosheets as Flexible Air Cathode for Rechargeable Zn-air Batteries

Graphical A bimetallic self-supporting electrode with 3D structure was synthesized. The electrode was composed of Cu, Co nanoparticles co-modified with nitrogen-doped carbon nanosheet (Cu, Co NPs@NCNSs/CC) on a carbon cloth. The dual-metal CuCo sites provide efficient ORR and OER electrocatalytic activity by the synergistic effect, thus reducing the energetic barrier. Exploring highly active and robust self-supporting air electrodes is the key for flexible Zn-air batteries (FZABs). Therefore, we report a novel 3D structural bimetal-based self-supporting electrode consisting of hybrid Cu, Co nanoparticles co-modified nitrogen-doped carbon nanosheets on carbon cloth (Cu, Co NPs@NCNSs/CC), which displays excellent electrochemical activity and durability of the oxygen reduction/evolution reaction (ORR/OER). The Cu, Co NPs@NCNSs/CC exhibits a half-wave potential of 0.863 V toward ORR and an overpotential of 225 mV at 10 mA cm −2 toward OER, owing to its exposed bimetallic sites accelerating the kinetic reaction. In addition, the density functional theory calculation proves that the synergistic effect of CuCo sites favors ORR and OER. Hence, the FZABs based on Cu, Co NPs@NCNSs/CC achieve a larger open-circuit potential (1.45 V), higher energy density (130.10 mW cm −2 ), and outstanding cycling stability. All remarkable results demonstrate valuable enlightenment for seeking advanced energy materials of portable and wearable electronics.