Effect of cobalt precursors on Co3O4 anodic catalyst for a membrane-free direct borohydride fuel cell

The fuel discharging efficiency of direct borohydride fuel cell (DBFC) depends on both the anodic catalyst activity and borohydride hydrolysis. In this paper, Co 3 O 4 anodic catalysts prepared from different cobalt sources used in DBFC have been investigated. It showed that the catalytic performance of Co 3 O 4 was associated with its microstructure that relied on the precursor. The maximum power densities obtained was 40, 62 and 28 mW cm −2 of DBFC with Co 3 O 4 catalyzed anode from CoCl 2 (marked DBFC-A), Co(NO 3 ) 2 (marked DBFC-B) and Co(CH 3 COO) 2 (marked DBFC-C), respectively. The Co 3 O 4 -A has the highest number of electron transfer ( n  =  7.06 ) which is close to the theoretical value ( n  =  8 ), and DBFC-A showed good voltage stability with specific capacity of 720 mAh.g −1 . A rapid voltage attenuation occurred in DBFC-B with the specific capacity of 330 mAh.g −1 because Co 3 O 4 from Co(NO 3 ) 2 has the higher catalytic activity for both borohydride oxidation reaction (BOR) and hydrolysis which lead to the lower fuel utilization efficiency.