In-situ growth of cobalt manganate spinel nanodots on carbon black toward high-performance zinc-air battery: Dual functions of 3-aminopropyltriethoxysilane

Copper nanodot-embedded nitrogen and fluorine co-doped porous carbon nanofibers as advanced electrocatalysts for rechargeable zinc-air batteries

Porous carbon-based electrocatalysts for cathodes in zinc-air batteries (ZABs) are limited by their low catalytic activity and poor electronic conductivity, making it difficult for them to be quickly commercialized. To solve these problems of ZABs, copper nanodot-embedded N, F co-doped porous carbon nanofibers (CuNDs@NFPCNFs) are prepared to enhance the electronic conductivity and catalytic activity in this study. The CuNDs@NFPCNFs exhibit excellent oxygen reduction reaction (ORR) performance based on experimental and density functional theory (DFT) simulation results. The copper nanodots (CuNDs) and N, F co-doped carbon nanofibers (NFPCNFs) synergistically enhance the electrocatalytic activity. The CuNDs in the NFPCNFs also enhance the electronic conductivity to facilitate electron transfer during the ORR. The open porous structure of the NFPCNFs promotes the fast diffusion of dissolved oxygen and the formation of abundant gas-liquid-solid interfaces, leading to enhanced ORR activity. Finally, the CuNDs@NFPCNFs show excellent ORR performance, maintaining 92.5% of the catalytic activity after a long-term ORR test of 20000 s. The CuNDs@NFPCNFs also demonstrate super stable charge-discharge cycling for over 400 h, a high specific capacity of 771.3 mAh g^-1 and an excellent power density of 204.9 mW cm^-2 as a cathode electrode in ZABs. This work is expected to provide reference and guidance for research on the mechanism of action of metal nanodot-enhanced carbon materials for ORR electrocatalyst design.

Research Progress on Porous Carbon-Based Non-Precious Metal Electrocatalysts

The development of efficient, stable, and economic electrocatalysts are key to the large-scale application of electrochemical energy conversion. Porous carbon-based non-precious metal electrocatalysts are considered to be the most promising materials to replace Pt-based catalysts, which are limited in large-scale applications due to high costs. Because of its high specific surface area and easily regulated structure, a porous carbon matrix is conducive to the dispersion of active sites and mass transfer, showing great potential in electrocatalysis. This review will focus on porous carbon-based non-precious metal electrocatalysts and summarize their new progress, focusing on the synthesis and design of porous carbon matrix, metal-free carbon-based catalysts, non-previous metal monatomic carbon-based catalyst, and non-precious metal nanoparticle carbon-based catalysts. In addition, current challenges and future trends will be discussed for better development of porous carbon-based non-precious metal electrocatalysts.

Hierarchically Porous Three-Dimensional (3D) Carbon Nanorod Networks with a High Content of FeNx Sites for Efficient Oxygen Reduction Reaction

Efficient, durable, and inexpensive electrocatalysts are recommendable for accelerating the kinetics of oxygen reduction reaction and achieving high performance. Herein, with predesigned hierarchically porous silica nanorods as a hard template, hierarchically macro-bimodal meso/microporous 3D carbon interwoven nanorod networks containing a high content of single-atom FeNx species (Fe/RNC) were prepared by melting of precursors and confined pyrolysis within the pores of the hard template. What distinguishes the use of silica nanorods as a hard template is that it not only provides a porous texture for confined pyrolysis of the precursors but also the interwoven texture of the nanorods gives rise to a macroporous mesh-like morphology. Benefiting from the ultrahigh iron content (5.69 wt %) of the FeNx sites, a 3D porous network configuration with high accessibility of active centers, as well as a high specific surface area of 793 m²g^-1, the as-prepared Fe/RNC exhibited superior activity and durability for ORR and zinc-air batteries. For comparison, the catalyst Fe/NC-MCM, which was prepared with a similar procedure but with unimodal mesoporous silica MCM-41 nanoparticles as the hard template, possesses a less porous structure and active accessibility and thus exhibits inferior ORR activity. This work provides an effective design/nanoengineering for electrocatalysts in ORR and zinc-air batteries and will inspire more research on accessibility of active sites in non-noble carbon-based electrocatalysts.