Short-range electronic engineering by coupling Fe phthalocyanines with MOF-derived N,S-doped carbon nanorods for oxygen reduction

Abstract

Molecular catalysts like metal phthalocyanines (MPc) hold significant promise for diverse applications in renewable energy conversion and storage. Despite their inherent catalytic activity in the oxygen reduction reaction (ORR), enhancing their practical applicability necessitates addressing challenges in electrical conductivity and catalytic stability through effective control of electron distribution within the substrate. In this work, we have successfully synthesized an electrocatalyst featuring FePc molecules anchored onto N,S co-doped carbon nanorods from a pillar-layer metal-organic framework (MOF), designated as ZTB-NSCR-FePc. This MOF-derived heteroatom-doped carbon substrate could be easily obtained by direct pyrolysis of a pre-fabricated rod-like Zn-TDC-bpy. The optimized ZTB-NSCR-FePc demonstrated exceptional electrocatalytic efficiency and stability towards ORR with a positive half-wave potential of 0.890 V. When employed in a Zn-air battery, it outperformed the benchmark Pt/C air cathode, achieving a peak power density of 198.9 mW cm⁻². Finally, theoretical calculations revealed that short-range electron interactions between N/S atoms and the graphene substrate significantly enhance the anchoring effect of FePc, improve the adsorption of reaction intermediates, and thereby boost the ORR performance.