A Confinement Strategy for Stabilizing ZIF‐Derived Bifunctional Catalysts as a Benchmark Cathode of Flexible All‐Solid‐State Zinc–Air Batteries

Abstract

Carbon composites with embedded metal/metal oxides represent a group of versatile electrochemical catalysts that has attracted extensive research attention. However, the beauty of this concept is marred by the severe carbon evaporation and the aggregation of metal species during their synthetic process, leading to the diminishment in active sites and catalytic durability. To address this issue, this study demonstrates the feasibility of utilizing Al2O3 nanolayer to trap volatile carbon and nitrogen species and alleviate the aggregation of Co species during the pyrolysis of the Zn/Co‐ZIFs (ZIF = zeolitic imidazolate framework). With the confinement effect of an Al2O3 nanolayer, the derived Co3O4‐embedded N‐doped porous carbon grown on carbon cloth presents outstanding bifunctional catalytic activity with a small potential difference of 787 mV between the half‐wave potential of the oxygen reduction reaction and an overpotential at 10 mA cm−2 of the oxygen evolution reaction. More impressively, an advanced flexible rechargeable zinc–air battery in all‐solid‐state configuration is assembled, which achieves the maximum power density of 72.4 mW cm−3 and good cycling stability. The insights produced in this work will provide guidance for the rational design of metal/carbon hybrid catalysts and low‐cost renewable energy systems.

Advanced Bifunctional Oxygen Reduction and Evolution Electrocatalyst Derived from Surface‐Mounted Metal–Organic Frameworks

“…In case of the ORR, the number of electrons transferred by 1 À NH 2 was calculated using the Koutecký -Levich (KL) equation. According to the slopes of the KL plots (Figure 4d and Figure S21), the number of electrons transferred per O 2 molecule in the ORR was Rotation speed:1 600 rpm; DE refer to the differencebetween the potential required for an OER current density of 10 mA cm À2 and the ORR half-wave potential;d )polarization curve of 1ÀNH 2 (supported on an Au disc electrode) at various rotational speeds;e)Comparison of bifunctional activities of ORR and OER with literature data:2:C oZn-NC-700, [31] 3:Co-N-CNTs, [32] 4: Co 3 O 4 -N-Carbon, [33] 5: NiCo 2 S 4 @g-C 3 N 4 -CNT, [34] 6: N-GCNT/FeCo, [35] 7: NC@Co-NGC, [36] Angewandte Chemie Forschungsartikel calculated to be 3.88, suggesting ap redominantly fourelectron reduction pathway.T hese results conclusively verify the capability of 1 À NH 2 to be agood bifunctional ORR/OER catalyst.…”

Two‐Dimensional Transition Metal Carbides and Nitrides (MXenes): Synthesis, Properties, and Electrochemical Energy Storage Applications

“…Nowadays, energy storage devices (ESDs) are playing a crucial role in smart electronics and wearable textiles. Rechargeable batteries (including Li, Na, K, Zn‐ions) as well as supercapacitors are being considered as promising energy storage devices for sustainable development of smart electronics . While batteries are known for their high energy density, the cycle life and charging/discharging rate are unfavorable in most cases .…”

Atomically Transition Metals on Self‐Supported Porous Carbon Flake Arrays as Binder‐Free Air Cathode for Wearable Zinc−Air Batteries

“…N 2 adsorption/desorption isotherms and pore size distributions show that hierarchical micro‐mesopores were generated in both Co NP@NCF/CNF and Co SA@NCF/CNF. The porous structures in original Co NP@NCF/CNF are mainly composed of mesopores character with the size of about 3.4 nm, whereas new pore structures are generated between 1 and 3 nm and around 25.2 nm in the acid‐treated sample, accompanied by the increased pore volume and Brunauer–Emmett–Teller surface area (from 361.64 to 696.00 m 3 g −1 ), which would be in favor of the fast mass transport as well as the improvement of active sites' accessibility in Co SA@NCF/CNF …”