High‐Density Atomic Fe–N₄/C in Tubular, Biomass‐Derived, Nitrogen‐Rich Porous Carbon as Air‐Electrodes for Flexible Zn–Air Batteries

Abstract

Developing low-cost single-atom catalysts (SACs) with high-density active sites for oxygen reduction/evolution reactions (ORR/OER) are desirable to promote the performance and application of metal-air batteries. Herein, the Fe nanoparticles are precisely regulated to Fe single atoms supported on the waste biomass corn silk (CS) based porous carbon for ORR and OER. The distinct hierarchical porous structure and hollow tube morphology are critical for boosting ORR/OER performance through exposing more accessible active sites, providing facile electron conductivity, and facilitating the mass transfer of reactant. Moreover, the enhanced intrinsic activity is mainly ascribed to the high Fe single-atom (4.3 wt.%) loading content in the as-synthesized catalyst. Moreover, the ultra-high N doping (10 wt.%) can compensate the insufficient OER performance of conventional FeNC catalysts. When as-prepared catalysts are assembled as air-electrodes in flexible Zn-air batteries, they perform a high peak power density of 101 mW cm −2 , a stable discharge-charge voltage gap of 0.73 V for >44 h, which shows a great potential for Zinc-air battery. This work provides an avenue to transform the renewable low-cost biomass materials into bifunctional electrocatalysts with high-density single-atom active sites and hierarchical porous structure.

Core–shell construction of metal@carbon by mechanochemically recycling plastic wastes: towards an efficient oxygen evolution reaction

“…S8,† and Δ j versus the scan rate for all the samples was shown in Fig. 6e. 101 Although IrO 2 showed a higher C dl value, its overpotential reached up to 329 mV, hence giving the highest Tafel slope of 78 mV dec −1 . 102 The highest electron transfer efficiency of Ni@PMMA-BM during the OER was also evidenced by the electrochemical impedance spectrum (EIS).…”

High‐Performance Neutral Zinc‐Air Batteries Based on Hybrid Zinc/Carbon Nanotube Fiber Anodes

“…Furthermore, the energy efficiencies were comparable to previously reported flexible ZABs with alkaline electrolytes (Table S2, Supporting Information). [ 3,15,27–33 ]…”

Intrinsic Carbon Defects in Nitrogen and Sulfur Doped Porous Carbon Nanotubes Accelerate Oxygen Reduction and Sulfur Reduction for Electrochemical Energy Conversion and Storage

“…and/or nonmetal (N, S, P, etc.) heteroatom doping in carbon matrices. ,,− The generation of extrinsic defects can regulate the electronic structure, create plenty of unsaturated sites, and hence offer preferable active centers for accelerating electrochemical kinetics. For example, He et al synthesized Co/N doped carbon nanotubes (CNTs) by grinding and subsequent calcination, which showed remarkable ORR performance .…”

“…The worsening global energy crisis and environmental pollution have been expediting the research and development of renewable and clean electrochemical energy conversion and storage facilities, including metal ion batteries, fuel cells, metal–air batteries, metal–sulfur batteries, and supercapacitors. , Among these devices, zinc–air batteries (ZABs) and lithium–sulfur batteries (LSBs) have been reckoned as promising candidates for future energy needs due to their seductive theoretical energy densities (about 1200 and 2600 Wh kg –1 for ZABs and LSBs, respectively), flexible designability, low cost, and environmental friendliness. − However, their widespread application has been hindered by the intractable sluggish kinetics of the cathodic oxygen reduction reaction (ORR) and sulfur reduction reaction (SRR). The cathodic ORR in ZABs is composed of multiple electron transfer processes including oxygen (O 2 ) adsorption, O–O bond breakage, and oxide intermediates/products detachment .…”