LAUSR

Hollow cobalt nitrogen‐doped carbon (H‐CoNC) is suggested for use in the membraneless hydrogen peroxide fuel cell (HPFC) and enzymatic biofuel cell (EBC) as anodic catalyst boosting hydrogen peroxide oxidation reaction (HPOR). For fabricating H‐CoNCs, a facile spray pyrolysis‐assisted process is used, and such produced H‐CoNCs show a porous and hollow‐shell structure, while they include a large amount of isolated Co atoms and coordinate bonds with Co and nitrogen (CoN4). This structure promotes mass transfer to the active site and excellent catalytic activity for HPOR. With these benefits of H‐CoNCs, the current density of the bioanode consisting of H‐CoNC, carbon nanotube, and glucose oxidase (H‐CoNC/CNT/GOx) observed at 0.3 V under 150 mM glucose is 315.5 μA cm−2, which is 2.1 times higher than that of a conventionally synthesized catalyst using Co‐doped carbon nanoparticles (CoNC‐NPs) (CoNC‐NPs/CNT/GOx, 146.2 μA cm−2). With this superior catalytic activity for HPOR, maximum power density (MPD) of membraneless EBC using H‐CoNC/CNT/GOx is 33.8 ± 4.52 μW cm−2, which is 52% higher than that of CoNP‐NPs/CNT/GOx. In addition, a membraneless HPFC using H‐CoNC/CNT demonstrates 4.87 times higher MPD (231.3 ± 11.3 μW cm−2) than that using CoNC‐NPs/CNT, proving that H‐CoNC improves the performance of fuel cells by its excellent catalytic activity.