3D Hierarchical Porous Carbon Aerogel Electrocatalysts Based on Cellulose/Aramid Nanofibers and Application in High-Performance Zn–Air Batteries

Three-dimensional (3D) carbon aerogels (CAs) are composed of interconnected networks and emerge as appealing platforms for the combination of heteroatom dopants, defective sites, and hierarchical porous structures. Here, we propose an effective and sustainable strategy to construct TOCNF/ANF-Cd hydrogels/aerogels using TEMPO-oxidized cellulose nanofibers (TOCNFs), thermally stabilized aramid nanofibers (ANFs), and low-boiling-point Cd2+. Hierarchical porous N-doped aerogel catalysts (N/CA-Cd) with TOCNF/ANF synergistic cross-linking were obtained by moderate temperature pyrolysis. Apart from serving as a source of N, ANF also improves carbon retention and graphitization, increasing the electrical conductivity of carbon aerogels. Due to the spatially continuous structure and multiscale porous structure and abundant N dopants and edges/defects, the as-obtained N/CA0.5-Cd carbonaceous catalysts manifest an impressive electrocatalytic efficacy with a positive half-wave potential (0.86 V). In particular, the Zn–air batteries assembled with N/CA0.5-Cd as the air cathode catalyst have an excellent peak power density of 186 mW cm–2 and a splendid specific capacity of 730 mA h g–1.