Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Abstract

AbstractIron phthalocyanine (FePc) with unique FeN4 site has attracted increasing interests as a promising non‐precious catalyst. However, the plane symmetric structure endows FePc with undesired catalytic performance toward the oxygen reduction reaction (ORR). Here, we report a novel one‐dimensional heterostructured ORR catalyst by coupling FePc at polyoxometalate‐encapsulated carbon nanotubes (FePc‐{PW12}@NTs) using host‐guest chemistry. The encapsulation of polyoxometalates can induce a local tensile strain of single‐walled NTs to strengthen the interactions with FePc. Both the strain and curvature effects of {PW12}@NT scaffold tune the geometric structure and electronic localization of FeN4 centers to enhance the ORR catalytic performance. As expected, such a heterostructured FePc‐{PW12}@NT electrocatalyst exhibits prominent durability, methanol tolerance, and ORR activity with a high half‐wave potential of 0.90 V and a low Tafel slope of 30.9 mV dec−1 in alkaline medium. Besides, the assembled zinc‐air battery demonstrates an ultrahigh power density of 280 mW cm−2, excellent charge/discharge ability and long‐term stability over 500 h, outperforming that of the commercial Pt/C+IrO2 cathode. This study offers a new strategy to design novel heterostructured catalysts and opens a new avenue to regulate the electrocatalytic performance of phthalocyanine molecules.