Interplay between Activation Processes, Physicochemical Properties and Electrochemical Performance of “Core-Shell” Carbon Nitride Pt-Ni ORR Electrocatalysts Based on Hierarchical Graphene Supports

The sluggishness of the kinetics of the oxygen reduction reaction (ORR) is one of the most relevant phenomena curtailing the operation capability of proton-exchange membrane fuel cells (PEMFCs)[1]. Hence, the development of advanced ORR electrocatalysts (ECs) is one of the main goals of the research in this field. The ECs described here exhibit a “core-shell” morphology: a hierarchical graphene-based support (H-GR)“core” is covered by a carbon nitride “shell” stabilizing the active sites in “coordination nests”[2]. The “core” comprises highly defected graphene nanoplatelets [3] and carbon black nanoparticles; the latter act as spacers and facilitate the charge and mass transport phenomena that take place during the EC operation. The ECs proposed here are characterized by a very low loading of platinum, on the order of ca. 5 wt%, that is the “active metal”; Ni is introduced as the “co-catalysts” to improve the performancies