Molecular iron phthalocyanine catalysts on morphology-engineered graphene towards the oxygen reduction reaction

Molecular catalysts dispersed on nanocarbon substrates represent a unique class of single atom catalysts (SACs) for their well-defined active sites and tailorable structures, and are promising substitutes to precious metals for catalyzing the technologically important oxygen reduction reaction (ORR). Herein, we develop a highly active ORR catalyst consisting of iron phthalocyanine uniformly and densely dispersed on puff-like graphene (FePc/PG). With the unique crumpled and spheroid morphology, the graphene carrier possesses a large surface area and multiscale porosity, benefiting the high-density loading of FePc, exposure of the active sites and mass transfer efficiency during catalysis. When evaluated by a rotating disk electrode, FePc/PG presents a high half-wave potential of 0.909 V vs. the reversible hydrogen electrode. Furthermore, when employed as the gas diffusion electrode, FePc/PG exhibits outstanding high-rate and highpower capabilities at practically high current densities. This work provides efficient strategies to engineer the morphology of the nanocarbon substrates to design high-performance heterogeneous molecular catalysts toward applications in diverse energy conversion and storage technologies. [Figure not available: see fulltext.]