CoO-Carbon@FeCoO Heterostructural Hollow Polyhedrons for the Oxygen Evolution Reaction.

Hollow heterostructured nanomaterials have received tremendous interest in new-generation electrocatalyst applications. However, the design and fabrication of such materials remain a significant challenge. In this work, we present CoO-carbon@FeCoO heterostructural hollow polyhedrons that have been fabricated by facile thermal treatment followed by solution-phase growth for application as efficient oxygen evolution reaction (OER) electrocatalysts. Starting from a single ZIF-67 hollow polyhedron, a novel complex structured composite material constructed from CoO nanocrystallite-embedded carbon matrix embedded with FeCoO nanowires was successfully prepared. The CoO nanocrystallite with oxygen vacancies provides both heterogeneous nucleation sites and growth platform for FeCoO nanowires. The resultant heterostructure combines the advantages of FeCoO nanowires with the large surface area and surface defects of CoO nanocrystallite, resulting in improved electrocatalytic activity and electrical conductivity. As a result, such novel heterostructured OER electrocatalysts exhibit much lower onset potential (1.52 V) and higher current density (70 mA/cm at 1.7 V) than CoO-carbon hollow polyhedrons (onset 1.55 V, 35 mA/cm at 1.7 V) and pure CoO hollow polyhedrons (onset 1.62 V, 5 mA/cm at 1.7 V). Furthermore, the design and synthesis of metal-organic framework (MOF)-derived nanomaterials in this work offer new opportunities for developing novel and efficient electrocatalysts in electrochemical devices.