Alkaline water electro-oxidation on ultralow Pt-Dispersed Co3O4: active role and synergistic interaction between Pt and Co3O4

In this work, a comparative electrochemical activity between Co3O4 and Pt nanoparticles supported Co3O4 (Pt/Co3O4) is investigated toward alkaline water electrolysis. The approach is to harness the metal–support interaction for high oxygen evolution reaction (OER) activity. Co3O4 is a known and promising catalyst for the oxygen evolution reaction (OER) in an alkaline medium, and here, it is demonstrated how the activity can be enhanced many times by dispersing an ultralow amount (0.5 wt %) of Pt nanoparticles over its surface. Quantitatively, a low overvoltage of 250 mV at 10 mA cm–2 and 340 mV at 100 mA cm–2 in 1.0 M KOH for the OER is obtained, which is remarkable. A lower Tafel slope of 131 mV dec–1 and a higher ECSA of 60 cm2 suggest good electrical conductivity. Noticeably, Co3O4 alone is less active than Pt/Co3O4, and Pt alone is poorly active for the OER reaction. However, the Pt/Co3O4 combination is super active. Finally, XPS and in situ Raman studies demonstrate the active role of Pt and Co3O4 and how they work in synergy. Eventually, the metal–support interaction phenomenon is ascertained, in which charge transfer occurs between Pt and Co3O4, Co2+ to Co3+ and Co3+ to Co4+ conversion promoted by Pt. Without Pt, this process is different, resulting in comparatively lower activity.