Oxygen reduction reaction on a polypyrrole-modified, carbon-supported cobalt hydroxide catalyst

► CoNx site of polypyrrole modified carbon-supported Co(OH)2 [Co(OH)2-PPY-C] catalysts leads to a 4-electron dominated oxygen reduction reaction (ORR). ► CNC site of Co(OH)2-PPY-C leads to a 2-electron dominated ORR. ► Catalytic activity of Co(OH)2-PPY-C catalysts toward ORR is determined by the competition between CoNx and CNC sites. ► A power density of 550 mW cm−2 is achieved by a direct borohydride fuel cell at 80 °C.