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Catalyzing oxygen reduction reaction (ORR) and accelerating oxygen diffusion are two key challenges for the requirements of the cathode catalysts in the metal‐air batteries. A promising strategy for improving both ORR performance and mass diffusion simultaneously is to build carbon‐based catalysts with ORR‐active chemical dopants and 3D interconnected porosity. Herein, a 3D nanoporous N‐doped carbon with bicontinuous porosity and interconnected open‐pore channels is reported, which is prepared by a polyaniline‐assisted template method. The polyaniline can efficiently inhibit the surface diffusion‐caused template coarsening, achieving a small pore size of 35 nm. The small porous morphology gives rise to a high N‐dopant concentration up to 7.20 at.%, which in turn exhibits a commercial Pt/C‐comparable ORR performance together with satisfied durability in alkaline media. Using these nanoporous carbon catalysts as air electrodes, an all‐solid‐state flexible Al‐air battery is assembled with the measured maximum power density reaching 130.5 mW cm−2, as compared to 106.2 mW cm−2 when the commercial Pt/C standard is used. This study provides an efficient method to synthesize 3D N‐doped carbon with bicontinuous nano‐sized pore channels for wide‐ranging applications in portable and flexible devices. [ABSTRACT FROM AUTHOR]

Keywords: Al-air batteries; nanoporous carbon; N-doped carbon; oxygen reduction reactions; surface diffusion suppression EN Al-air batteries nanoporous carbon N-doped carbon oxygen reduction reactions surface diffusion suppression 1 1 1 09/20/21 20210908 NES 210908 B Nanoporous Carbon b In article number 2103632 Kailong Hu, Hua-jun Qiu, Yoshikazu Ito, and co-workers report a polyaniline-assisted template method to synthesize 3D bicontinuous nanoporous N-doped carbon particles. Al-air batteries, nanoporous carbon, N-doped carbon, oxygen reduction reactions, surface diffusion suppression Inhibiting Surface Diffusion to Synthesize 3D Bicontinuous Nanoporous N-Doped Carbon for Boosting Oxygen Reduction Reaction in Flexible All-Solid-State Al-Air Batteries (Adv. Funct. [Extracted from the article]

[Display omitted] • A general strategy is proposed for the upcycling of residual anodes derived from retired Li-ion batteries into highly valuable electrocatalysts. • The LIB residues are converted into Mn oxide nanoparticles anchored by N and S sites on rGO nanosheets (Mn/NS-rGO). • The binding between Mn and N/S dopants simultaneously optimizes the intermediate adsorption and charge distribution at Mn/rGO interface. • Mn/NS-rGO assembled Al-air battery exhibits an excellent discharge performance under flexible working conditions. Upcycling retired lithium-ion batteries (LIBs) into value-added electrocatalysts represents a promising strategy for tuning the trash into treasure. Herein, an effective approach is reported to convert the LIB anode residues into electrocatalysts that enhance the oxygen reduction reaction (ORR). The residues are utilized for synthesizing reduced graphene oxides (rGO) with Mn nanoparticles anchored by N and S dopants (Mn/NS-rGO). A Pt/C-comparable ORR performance is achieved in alkaline media, with the onset and half-wave potentials of 1.01 and 0.87 V, as well as the excellent durability. Density functional theory (DFT) calculations reveal that Mn sites, coordinating with N and S dopants, simultaneously optimize the intermediate adsorption and charge distribution, which in turn facilitates ORR. The solid-state Al-air batteries are assembled by using Mn/NS-rGO as the cathode catalyst, showing the power density of 103.8 mW cm −2, which successfully charge a cell phone and power LED lights under flexible working conditions. [ABSTRACT FROM AUTHOR]