Heterostructure design in bimetallic phthalocyanine boosts oxygen reduction reaction activity and durability

Iron phthalocyanine (FePc) has inspired substantial interest in the context of the oxygen reduction reaction (ORR) owing to its prominent catalytic activity in alkaline media; however, its poor stability significantly hinders its practical applications. Heterostructures with a strong coupling effect between different components have considerable potential to promote the activity and stability simultaneously. Hence, a heterostructured bimetallic phthalocyanine (FePc/CoPc HS) catalyst with heterogeneous distribution of metallic elements is designed. Compared with FePc, FePc/CoPc HS demonstrates higher kinetic current density (increased by >100%) and more robust durability (enhanced by 20.5%) for the ORR. In addition, a Zn-air battery with FePc/CoPc HS as the cathode catalyst achieves high power density (128 mW cm(-2)) and high open-circuit voltage (1.67 V). X-ray absorption fine structure and theoretical calculations reveal that the heterostructure design induced elongates the Fe-N bond length, and augments electron density around the Fe active sites, and reduced highest-occupied molecular orbital and lowest-unoccupied molecular orbital energy gap are responsible for the boosted ORR performance. This work enriches the understanding of electronic structure modulation of heterostructured bimetallic phthalocyanine based ORR electrocatalysts