Synergistic Bimetallic CoCu‐Codecorated Carbon Nanosheet Arrays as Integrated Bifunctional Cathodes for High‐Performance Rechargeable/Flexible Zinc‐Air Batteries

Abstract

Nonetheless, the sluggish oxygen reduction/evolution reaction (ORR/OER) involving multi-step electron transfer at the multiphase interfaces of the airbreathing cathode deleteriously impact the energy efficiency and lifespan of ZABs with limited energy/power output. [4] Until now, noble-metal-based catalysts, that is, Pt/C and IrO 2 or RuO 2 , still stand out as the benchmark catalysts for ORR and OER, respectively, though the rare reserve and chemical susceptibility severely hinder their large-scale application. [5] Indeed, tremendous efforts have been made on the exploitation of proficient earth-abundant transition-metal based bifunctional oxygen catalysts, such as oxides, hydroxides, phosphides, sulfides, nitrides, etc., so as to activate the OER/ORR electrochemistry. [6][7][8][9] Unfortunately, ideal non-precious electrocatalysts with satisfactory bifunctional activities, robust durability, and appropriate structure for unobstructive mass transport are still very scarce. [10] Among diverse non-precious electrocatalysts, nanosized and atomically dispersed metallic Co-based catalysts have intrigued numerous recognition by virtue of the rich valence states for high OER activity, electrochemical stability, and abundance of cobalt resources. [11][12][13] By further conjugation with an N-doped carbon matrix to tune the coordination configuration between Co and N heteroatoms, the electronic structure of Co sites can be effectively optimized for more balanced adsorption of oxo-intermediates and improved ORR activity. [14][15][16] However, the formation of homogeneous and sufficient Co-N x active moieties is generally difficult, as the metallic loading in these Co-N-C catalysts is always restricted due to the high tendency of self-agglomeration and irreversible fusion of cobalt nanoparticles (NPs) during common pyrolysis synthesis. [17,18] By taking advantage of high specific surface area, excellent conductivity, and mechanical strength, heteroatoms-doped 2D nanocarbon could be useful to support and well distribute Co NPs for more exposed active sites, directional electron transfer and accelerated mass diffusion across the interspaces between the carbon nanosheets (CNSs), thus boosting the reversible oxygen reactions. [19,20] Besides, feasible strategies, including morphological control, heterostructure, surface reconfiguration, and interface

Interface engineering of bifunctional oxygen electrocatalysts for rechargeable Zn–air batteries

“…29 Recently, many efforts have been devoted to developing dual-single-atom catalysts (DSACs) via the pairing and/or long-range coupling of two metallic active sites for efficient bifunctional oxygen catalysis. 56,[59][60][61] Very recently, by adopting the strategy of atomic-interfacial regulation, Yasin et al designed a catalyst with dual single Fe/Co atoms trapped by defective/graphitic/porous S,N-doped carbon nanosheets (Fe,Co/DSA-NSC). 60 Thanks to the synergistic interaction and abundant active sites, Fe,Co/DSA-NSC delivered a high E 1/2 of 0.879 V (vs. RHE) for the ORR and a low overpotential of 0.21 (vs. RHE) for the OER, as well as satisfactory cycling stability for RZABs.…”

“…Heteroatom doping has been performed mainly to modify the electrical conductivity, electron redistribution, atomic configuration, and synergies among the multiple components in order to improve the electrocatalytic activity and stability of the OER and ORR in RZABs. 30,61 In the ''single-atom active site engineering'' section, we discussed doping heteroatoms into nitrogen-doped carbon materials as an effective strategy to affect the nature of supports and optimize the catalytic behavior of SACs. In this section, we focus on discussion of how the hosting atoms are directly altered by the introduced heteroatoms.…”

“…Kuang et al synthesized a satisfactory ORR/OER bifunctional electrocatalyst (referred to as CoCu/N-CNS) by introducing a suitable amount of Cu into the Co-modified carbon nanosheet arrays. 61 Owing to the strong bimetallic electronic interaction and synergistic effect, the incorporation of a moderate amount of Cu can improve the intrinsic activity toward the OER/ORR. The assembled liquid RZABs showed superior electrochemical performance with cyclic stability of 400 h/ 1000 cycles at 10 mA cm À2 .…”

Novel application of imidazole-based ligand-templated borates in a zinc–air battery

“…The ORR is a complex reaction and involves not only surface charge but also the interaction between oxygen atoms. [7][8][9][10] Therefore, in the process of oxygen reduction, the utilization of electrocatalysts is the key to reducing overpotential. [11][12][13][14][15] At present, in the study of oxygen reduction catalytic materials, precious metal catalysts and MOFs catalytic materials are mainly used.…”

“…The ORR is a complex reaction and involves not only surface charge but also the interaction between oxygen atoms. 7–10…”