3D Hierarchical Core–Shell Nanostructured Arrays on Carbon Fibers as Catalysts for Direct Urea Fuel Cells

Bifunctional cobalt oxide (Co 3 O 4 ) nanowire catalysts grown on carbon cloth (CC) fibers and their modification with nickel oxide (NiO) and manganese dioxide (MnO 2 ) to produce core–shell nanoarchitectures are explored as catalysts for urea oxidation reaction and oxygen reduction reaction in direct urea fuel cells (DUFC). Based on a systematic electrochemical characterization of the catalyst, the as‐developed core–shell nanoarchitectures are optimized toward DUFC performance. Under alkaline conditions with an anion exchange membrane, the DUFC with a cell configuration of Co 3 O 4 @NiO(1:2)/CC(a|c)Co 3 O 4 @MnO 2 (1:2)/CC exhibits a maximum power density of 33.8 mW cm −2 with excellent durability for 120 h without any performance loss. Furthermore, the DUFC exhibits a maximum power density of 23.2 mW cm −2 with human urine as a fuel. These findings offer an approach to convert human waste into treasure.