Carbon nanotubes anchored onto hollow carbon for efficient oxygen reduction

The rational design and facile construction of non-noble metal-based electrocatalysts for efficient oxygen reduction reaction (ORR) remain a challenge for the development of clean energy conversion devices. Herein, we synthesized a new type of hierarchical hollow carbon nanomaterials through one-step pyrolysis on bimetallic ZIF-Zn/Co precursors. The obtained hollow N-doped carbon composites, denoted as HNCT-CNTs, are enriched with Co-Nx sites and in-situ formed multi-walled carbon nanotubes (CNTs). Theoretical and experimental studies confirmed that the obtained HNCT-CNT exhibits excellent ORR catalytic activity with a reduced energy barrier for ORR intermediates. Owing to these advantages, the optimal catalyst shows an excellent half-wave potential of 0.85 V, a limiting current density up to 6.36 mA cm−2, a Tafel slope of 58.2 mV dec−1, and robust stability. Furthermore, the assembled Zn-air battery based on HNCT-CNT also displays an open circuit voltage of 1.49 V and a satisfactory power density of 116.56 mW cm−2. This template-directed preparation method opens up an interesting and efficient route to fabricate highly active non-noble metal-doped carbon nanomaterials for a wide range of electrochemical energy applications.