Self‐Catalyzed Growth of Co, N‐Codoped CNTs on Carbon‐Encased CoS_x Surface: A Noble‐Metal‐Free Bifunctional Oxygen Electrocatalyst for Flexible Solid Zn–Air Batteries

Abstract

The self‐catalyzed growth of nanostructures on material surfaces is one of the most time‐ and cost‐effective ways to design multifunctional catalysts for a wide range of applications. Herein, the use of this technique to develop a multicomponent composite catalyst with CoSx core encapsulated in an ultrathin porous carbon shell entangled with Co, N‐codoped carbon nanotubes is reported. The as‐prepared catalyst has a superior catalytic activity for oxygen evolution and oxygen reduction reactions, an ultralow potential gap of 0.74 V, and outstanding durability, surpassing most previous reports. Such superiority is ascribed, in part, to the unique 3D electrode architecture of the composite, which is favorable for transporting oxygen species and electrons and creates a synergy between the components with different functionalities. Moreover, the flexible solid Zn–air battery assembled with such an air electrode shows a steady discharge voltage plateau of 1.25 V and a round‐trip efficiency of 70% at 1 mA cm−2. This work presents a simple strategy to design highly efficient bifunctional oxygen electrocatalysts and may pave the way for the practical application of these materials in many energy conversion/storage devices.

Metal‐organic framework‐derived Fe/Cu‐substituted Co nanoparticles embedded in CNTs‐grafted carbon polyhedron for Zn‐air batteries

“…This highly porous structure was favorable for the interaction with the electrolyte and mass transport in the heterogeneous oxygen electrocatalysis. 37 The chemical state and molecular environment of FC-C@NC and other composites were further characterized by XPS. The survey spectrum ( Figure S4) of FC-C@NC clearly showed the peaks of Co, Fe, Cu, C, N, F I G U R E 2 Morphology and structure characterizations of MM-ZIF and FC-C@NC.…”

Highly Reversible Zn Anode Enabled by Controllable Formation of Nucleation Sites for Zn‐Based Batteries

“…In this regard, metallic zinc (Zn) has been considered to be one of the alternatives due to its low potential (−0.762 V vs standard hydrogen electrode (SHE)), high theoretical capacity (820 mAh g −1 ), large abundance, environmental‐friendly properties, and inherent safety 7–9. Up to now, various Zn‐based batteries have been widely investigated, such as Zn–air battery,10–13 Zn–NiOOH battery,14–16 Zn–V 2 O 5 battery,17–19 Zn–MnO 2 battery,20–23 etc. However, besides the dendrite growth in the electrolyte, the Zn anode corrosion and the formation of ZnO densification on the Zn electrode surface have become the challenges for the development of rechargeable Zn‐based batteries, which would result in poor reversibility, low Coulombic efficiency (CE), and the decayed capacity 24.…”

A Freestanding 3D Heterostructure Film Stitched by MOF‐Derived Carbon Nanotube Microsphere Superstructure and Reduced Graphene Oxide Sheets: A Superior Multifunctional Electrode for Overall Water Splitting and Zn–Air Batteries

“…The CNT-HM superstructure and higher N-doped provide more active sites and optimize the adsorption energy for various steps of electrochemical reactions via the regulation of the surface properties and electronic structure of the carbon matrix, thus improving the electrocatalytic performances of the films. [22] Based on previous reports, alkaline-efficient electrocatalysts are extremely important because the most frequently used technology in practical applications is alkaline electrolysis. [9a] Inspired by the special structure and anticipated composition, the electrocatalytic performance of the CGHF was evaluated in alkaline media (1.0 m KOH for HER and OER and 0.1 m KOH for ORR) using a standard three-electrode system.…”