Optimizing Metal-free phenanthroline-assisted nitrogen-doped reduced graphene oxide for enhanced oxygen reduction reaction: an experimental design and performance study - Oliveira, Eleilde de Sousa; Figueredo, Adolfo Lopes; Gothe, Maitê Lippel; Vidinha, Pedro; Tanaka, Auro Atsushi; Garcia, Marco Aurélio Suller (Electrocatalysis, 2025)