Solvent-free synthesis of ZrO2 nanoparticles/nitrogen-rich two-dimensional carbon nanosheet composites as efficient catalysts for ORR

[Display omitted] •Synthesis route: a straightforward, solvent-free, and one-step pyrolysis approach.•Well-dispersed tetragonal ZrO2, appropriate N dopants, and hierarchical pores.•Synergistic catalytic effect endow good ORR performance and high power density. An innovative, high-performance, non-noble-metal-based oxygen reduction reaction (ORR) catalyst must be developed utilizing a new and cost-effective technique. ZrO2 has the merits of high stability, low toxicity, good catalytic activity, and low enthalpy for atomic oxygen adsorption. However, the poor conductivity restricts its application as an ORR catalyst. Here, we successfully prepared ZrO2 nanoparticles / nitrogen-rich two-dimensional carbon nanosheet composites as ORR catalysts using a straightforward, solvent-free, one-step pyrolysis approach. Due to the unique component and structure characteristics, ZrO2@N-C-900 demonstrates remarkable ORR performances in alkaline electrolytes, such as high half-wave potential (0.82 V vs. RHE), higher current density (JL = 6.4 mA cm−2), and outstanding long term stability (95 % for 36,000 s). Especially, when used in a Zn-air battery, ZrO2@N-C-900 exhibited a power density of 148 mW cm−2, exceeding that of 20 % Pt/C.