The use of polypyrrole modified carbon-supported cobalt hydroxide as cathode and anode catalysts for the direct borohydride fuel cell

A polypyrrole modified carbon-supported cobalt hydroxide (Co(OH)2-PPY-C) has been prepared by the impregnation-chemical method and used as the electrode catalyst in a direct borohydride fuel cell (DBFC). The microstructure of Co(OH)2-PPY-C has been characterized by X-ray diffraction and transmission electron microscopy. The cell performance and short-term performance stability of the DBFC using the Co(OH)2-PPY-C as catalysts have been investigated. A maximum power density of 83 mW cm−2 has been achieved at 0.6 V under ambient conditions. The Co(OH)2-PPY-C catalyst demonstrates a smaller value of polarization than the carbon-supported Co(OH)2 catalyst. Results from electrochemical impedance spectrum analysis confirm that the polypyrrole addition to the cathode effectively decreases its resistance. During operation of the DBFC using Co(OH)2-PPY-C as catalyst, the Co(OH)2 tends to be converted into CoHO2.