Highly Nitrogen-Doped Carbon Nanotube Nanoarrays as Self-supported Bifunctional Electrocatalysts for Rechargeable and Flexible Zinc-Air Batteries

Abstract

Rational design of bifunctional electrocatalysts to promote the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a fundamental challenge for the application of zinc-air batteries (ZABs). Herein, we propose a facile and cost-effective strategy to in situ grow N-doped carbon nanotubes with encapsulated FeCo alloy nanoparticles on carbon cloths (FeCo/N-CNTs@CC) as a self-supported air cathode for rechargeable ZABs. The bamboo-like FeCo/N-CNTs@CC catalyst with high nitrogen content (10.5 atom %) exhibits excellent electrocatalytic activities, including a half-wave potential of 0.816 V for ORR and an overpotential of 1.638 V for OER at 10 mA cm–2 in alkaline medium. Impressively, the liquid-state ZAB based on the FeCo/N-CNTs@CC cathode demonstrates a remarkable power density of 132.0 mW cm–2 and a stable cycling performance over 65 h. Furthermore, the flexible all-solid-state ZAB possesses outstanding performance retention under various bending conditions. The electrocatalyst presented in this work holds great potential as a self-supported air cathode for practical applications.

In situconstruction of FeCo alloy nanoparticles embedded in nitrogen-doped bamboo-like carbon nanotubes as a bifunctional electrocatalyst for Zn–air batteries

“…3c, two characteristic peaks with binding energies of nearly 707.5 and 721.1 eV are designated to the zero valence Fe atom, ascribable to metallic Fe in the FeCo alloy, and the peaks centered at 711.9 and 725.1 eV with shakeup satellites (denoted as “Sat.”) at 715.6 and 732.6 eV are assigned to the ionic state Fe atom, indicating the formation of Fe–N x species. 11,23 Similarly, the Co 2p spectrum shows zero valence Co (779.1 and 793.9 eV) and ionic state (781.6 and 796.5 eV) Co with shakeup satellites (786.9 and 801.7 eV), which are derived from the FeCo alloy and Co–N x species, 32,35 respectively. Such co-existence of Co–N and Fe–N bonds suggests the strong coupling interactions between the FeCo alloy nanoparticle and the N-doped graphitic carbon shell, which is consistent with the HRTEM results.…”

“…S5b†), three diffraction peaks at 26.3°, 44.7°, and 65.2° can be attributed to the (002) plane of graphitic carbon and the (110) and (200) planes of the FeCo alloy (no. 49-1568), respectively, 23,30 indicating that the FeCo alloy nanoparticles are formed during the high-temperature stage. In addition, the XRD pattern of FeCo/CB-800 also shows the FeCo alloy phase under thermal reduction of carbon black (Fig.…”

“…4c and d) show good linearity, signifying the first-order reaction kinetics of FeCo/N–CNTs-800. 23 The number of transferred electrons ( n ) for the FeCo/N–CNTs-800 electrode is estimated to be 3.8–4.0, manifesting a near-4-electron ORR pathway. Importantly, the calculated n value is close to that of commercial Pt/C ( n = 3.8–3.9) (Fig.…”

Air Electrodes for Flexible and Rechargeable Zn−Air Batteries

“…Generally, the array‐structured bifunctional catalysts were constructed via easily controlled chemical deposition followed by a pyrolysis process. [ 205–207 ] Chen and co‐workers developed a 3D array structured air electrode through directly growing Co 3 O 4 nanowires on the surface of SS mesh without using nonconductive ancillary binding materials. [ 58 ] Based on this pioneering work, they designed a developed hair‐like catalyst array structure, which contained a nanoassembly of 2D mesoporous Co 3 O 4 nanopetals anchored on 1D NCNTs (Co 3 O 4 −NCNT), as shown in Figure 9b.…”

Recent Advances in Metal–Gas Batteries with Carbon‐Based Nonprecious Metal Catalysts

“…[92][93][94] Based on CVD, many methods of preparing carbon-based catalysts have been reported in recent years. [95][96][97] Doping in the flow direction under an inert atmosphere within CVD is a common method for preparing electrocatalysts. Many oxygens electrochemical catalysts were prepared by Reproduced with permission.…”