Alkaline Water Electro-oxidation on Ultralow Pt-Dispersed Co 3 O 4 : Active Role and Synergistic Interaction between Pt and Co 3 O 4

In this work, a comparative electrochemical activity between Co 3 O 4 and Pt nanoparticles supported Co 3 O 4 (Pt/Co 3 O 4 ) is investigated toward alkaline water electrolysis. The approach is to harness the metal–support interaction for high oxygen evolution reaction (OER) activity. Co 3 O 4 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 cm 2 suggest good electrical conductivity. Noticeably, Co 3 O 4 alone is less active than Pt/Co 3 O 4, and Pt alone is poorly active for the OER reaction. However, the Pt/Co 3 O 4 combination is super active. Finally, XPS and in situ Raman studies demonstrate the active role of Pt and Co 3 O 4 and how they work in synergy. Eventually, the metal–support interaction phenomenon is ascertained, in which charge transfer occurs between Pt and Co 3 O 4, Co 2+ to Co 3+ and Co 3+ to Co 4+ conversion promoted by Pt. Without Pt, this process is different, resulting in comparatively lower activity.