The effects of cobalt phthalocyanine and polyacrylic acid on the reactivity of hydrogen peroxide oxidation reaction and the performance of hydrogen peroxide fuel cell

A catalyst capable of high performance and good durability is developed for use in anode of flow-type membraneless hydrogen peroxide fuel cells (HPFCs). For that, cobalt phthalocyanine (CoPc) is immobilized onto reduced graphene oxide (rGO) linked to polyacrylic acid (PAA) surface modifier (rGO/PAA/CoPc). CoPc moiety containing PAA is tightly immobilized due to physical entrapment, axial ligand and stabilization of intermediates. According to evaluations, the amount of CoPc immobilized in rGO/PAA/CoPc is twice than that in rGO/CoPc because rGO and CoPc are weakly connected by π-π conjugation without PAA acting as axial ligand to form coordinate bond with Co core within CoPc. In rGO/PAA/CoPc, current density for hydrogen peroxide oxidation reaction (HPOR) is 2.7 times higher than that measured in rGO/CoPc due to axial ligand role of PAA activating two HPOR pathways, wheras rGO/CoPc is only linked to one HPOR pathway. Even in stability test, rGO/PAA/CoPc preserves 90.0% of its initial HPOR current density, while that of Ni bulk is decreased by 30.6%. When performance of HPFC using rGO/PAA/CoPc is measured with a low concentration of H₂O₂ (0.1 mol L^-1) under physiological condition, its maximum power density (72.1 ± 2.68 μWcm⁻²) is better than that of HPFC using rGO/CoPc (38.3 ± 0.20 μWcm⁻²).