Closely packed planar polyphthalocyanine iron/hierarchical three-dimensional graphene as an oxygen electrocatalyst for the ORR and OER, and zinc–air batteries†
Abstract
The development of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts with high performance and excellent stability is meaningful for fuel cells. Herein, two-dimensional closely packed amide polyphthalocyanine iron (CPMPcFe) supported on hierarchical three-dimensional graphene (3D-HG) has been well prepared. CPMPcFe/3D-HG possessed a micro–mesoporous graphene structure where CPMPcFe was uniformly distributed in the inner and surface of the 3D-HG. Owing to the π bonds of both CPMPcFe and 3D-HG, there is a powerful π–π bond interaction between CPMPcFe and 3D-HG, which increases the electron cloud density, and it could be beneficial for improving the catalytic activity and durability. Electrochemically, CPMPcFe/3D-HG exhibits an excellent half-wave potential of 0.88 V (vs. RHE), and the electron transfer number of CPMPcFe/3D-HG is 3.99 @ 0.6 V (vs. RHE). The small value of overvoltage further indicates the excellent bifunctional catalytic performance. Additionally, a home-built Zn–air battery with CPMPcFe/3D-HG as the cathode exhibits a high power density of 193 mW cm−2, a specific capacity of 683 mA h g−1, and remarkable long-term stability. These results indicated that CPMPcFe/3D-HG could be a promising electrocatalyst for metal–air batteries.