Fluorinated cobalt phthalocyanine axially coordinated to oxo functionalities on different dimensional carbon (1D–3D) for durable oxygen reduction reaction

The development of low-cost, durable and easily available electrocatalysts as alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR) will promote the large-scale commercial application of fuel cells and metal-air batteries. Among the transition metal based N4-metallomacrocyclic molecules, the Co macrocycle catalyst usually exhibits superior long-term durability and stability than the Fe family. Developing efficient Co-N4 ORR electrocatalyst is of great significance. In the work, fluorinated cobalt phthalocyanine (CoPcF16) were anchored on various carbon materials in different structural dimensions (1–3D) including 1D carboxyl carbon nanotube (CNT), 1D carbon nanofibers (CNF), 2D nitrogen doped graphene (N-G), and 3D ordered mesoporous carbon CMK-3, which were explored and investigated as electrocatalysts for ORR. The results show that the molecular CoPcF16 anchored on theses carbon materials exhibited different electrocatalytic activity with the increased half-wave potential (E1/2) order of CMK-3>CNT>N-G>CNF, which is related to oxo functionalities (axial coordination to Co), porous structures and defective sites. The CoPcF16-carbons hybrids exhibited much lower tafel slope and comparable E1/2 than commercial Pt/C catalysts for ORR. The prepared catalysts also demonstrated excellent stability even after 5000 cycling. CoPcF16-carbons hybrids will be potential candidates to replace Pt-based catalysts for PEMFCs applications in future.