Bimetallic carbon nanotube encapsulated Fe-Ni catalysts from fast pyrolysis of waste plastics and their oxygen reduction properties.

Carbon-based bimetallic electrocatalysts were obtained by catalytic pyrolysis of waste plastics with Fe-Ni-based catalysts and were used as efficient oxygen reduction reaction (ORR) catalysts in this study. The prepared iron-nickel alloy nanoparticles encapsulated in oxidized carbon nanotubes (FeNi-OCNTs) are solid products with a unique structure. Moreover, the chemical composition and structural features of FeNi-OCNTs were determined. The iron-nickel alloy nanoparticles were wrapped in carbon layers, and the carbon nanotubes had an outer diameter of 20-50 nm and micron-scale lengths. FeNi-OCNT with a Fe/Ni ratio of 1:2 (FeNi-OCNT12) exhibited remarkable electrochemical performance as an ORR catalyst with a positive onset potential of 1.01 V (vs. RHE) and a half-wave potential of 0.87 V (vs. RHE), which were comparable to those of a commercial 20% Pt/C catalyst. Furthermore, FeNi-OCNT12 exhibited promising long-term stability and higher tolerance to methanol than the commercial 20% Pt/C catalyst in an alkaline medium. These properties were attributable to the protective OCNT coating of the iron-nickel alloy nanoparticles.