Oxygen Engineering Enables N-Doped Porous Carbon Nanofibers as Oxygen Reduction/Evolution Reaction Electrocatalysts for Flexible Zinc–Air Batteries

Abstract

Controllable designing of heteroatom-doped carbon catalysts provides an insightful strategy for boosting the performance and kinetics of the oxygen reduction/evolution reaction (ORR/OER). However, the role of oxygen species is usually omitted. Herein, a facile oxygen engineering strategy is proposed to tune the oxygen species in N-doped porous carbon nanofibers (NPCNFs-O) via a facile electrospinning method, in which βcyclodextrin acts as the pore inducer and oxygen regulator. Benefitting from the large specific surface area and synergistic effect of N,O codoping, the NPCNF-O catalyst exhibits superior ORR (E 1/2 = 0.85 V vs reversible hydrogen electrode (RHE)) and OER (E j = 10 = 1.556 V vs RHE) activities with excellent stability. Both experimental and theoretical calculations verify the crucial role of carboxyl groups, which regulate the local charge density and reduce the reaction energy barrier for enhancing the oxygen electrocatalytic activity. Moreover, a rechargeable zinc−air battery using NPCNF-O as the air cathode demonstrates a maximum power density of 125.1 mW cm −2 and long-term durability. Importantly, NPCNF-O can be served as an integrated freestanding electrode for portable zinc−air batteries. The work brings brilliant fundamental insights for constructing efficient metal-free carbon material catalysts for future energy conversion and storage systems.

Double-Faced Atomic-Level Engineering of Hollow Carbon Nanofibers as Free-Standing Bifunctional Oxygen Electrocatalysts for Flexible Zn–Air Battery

“…The bending strength of Ni-SAs/HCNFs/Co-NAs membrane reaches at 1.83 MPa, indicating a good capability of mechanical deformations. The value of bending strength is comparable to previously reported carbon membrane catalysts. − Furthermore, the Ni-SAs/HCNFs/Co-NAs after cycling stability based on ZABs is also investigated by SEM (Figures S37a and S37b in the Supporting Information), XRD (Figure S37c in the Supporting Information), and HADDF-STEM image (Figure S37d in the Supporting Information), which almost stands the original states, further proves its stability. Thus, the as-fabricated flexible free-standing Ni-SAs/HCNFs/Co-NAs electrode shows promising potential in portable and wearable solid ZABs.…”

N,S-Doped hollow carbon nanosheet-encapsulated Co9S8 nanoparticles as a highly efficient bifunctional electrocatalyst for rechargeable zinc–air batteries

“…8,9 Nevertheless, the applicability of the above catalysts is constrained by factors such as resource scarcity, prohibitive costs, and being monofunctional. 10,11 Therefore, the exploration of costefficient and high activity bifunctional electrocatalysts based on non-noble metals for ZAB air electrodes is of high priority.…”

2D Zinc-Based Metal–Organic Complexes Derived N-Doped Porous Carbon Nanosheets as Durable Air Cathode for Rechargeable Zn–Air Batteries

“…Hence, it is of great significance to develop clean and renewable energy storage and conversion devices [1][2][3][4][5][6][7]. Among the devices, zinc−air batteries (ZABs) are recognized as a promising candidate because of their low-cost, high safety, environmental friendliness, high theoretical energy density (1086 Wh kg −1 ), and high power density [8,9]. However, the oxygen reduction reaction (ORR) on the cathode acts as one key chemical reaction in the ZABs, which is subject to sluggish kinetics and high overpotential [10,11].…”