Hierarchical nanostructures with hollow architectures can provide rich active sites, improved transport of ions, and highly robust structure for electrochemical applications. In this work, we report the self-templated fabrication of hierarchical manganese-cobalt phosphide (Mn-Co phosphide) yolk-shell spheres using highly uniform cobalt glycerate spheres as sacrificial templates. Through a simple exchange reaction with the manganese precursor solution at room temperature, these cobalt glycerate spheres are readily converted to hierarchical Mn-Co LDH yolk-shell spheres, which can be further phosphidized at 350 °C under inert atmosphere to generate hierarchical Mn-Co phosphide with distinct yolk-shell morphology. When tested as an electrocatalyst for oxygen evolution reaction (OER), the hierarchical Mn-Co phosphide yolk-shell spheres exhibit an overpotential of 330 mV at a current density of 10 mA cm−2 and a Tafel slope of 59.0 mV dec-1, which are higher than those of Mn-Co oxide yolk-shell spheres (480 mV and 113 mV dec-1) and hierarchical cobalt phosphide spheres (410 mV and 61.3 mV dec-1). Post-OER analysis by XPS reveals that the high activity of the hierarchical Mn-Co phosphide yolk-shell catalyst originates from the existence of Mn4+/Mn3+ and Co2+/Co3+ redox couples and the formation of active metal oxyhydroxide species on its surface. The proposed self-sacrificial templating strategy will provide useful guidance for future construction of hollow inorganic metal nanostructures with yolk-shell morphology for energy storage and conversion applications.
ASJC Scopus subject areas
- 化学 (全般)