The Oxygen Reduction Pathway for Spinel Metal Oxides in Alkaline Media: An Experimentally Supported Ab Initio Study

Kavli Affiliate: Hector D. Abruna

| First 5 Authors: Colin R. Bundschu, Mahdi Ahmadi, Juan F. Méndez-Valderrama, Yao Yang, Héctor D. Abruña

| Summary:

Precious-metal-free spinel oxide electrocatalysts are promising candidates
for catalyzing the oxygen reduction reaction (ORR) in alkaline fuel cells. In
this theory-driven study, we use joint density-functional theory in tandem with
supporting electrochemical measurements to identify a novel theoretical pathway
for the ORR on cubic Co3O4 nanoparticle electrocatalysts. This pathway aligns
more closely with experimental results than previous models. The new pathway
employs the cracked adsorbates *(OH)(O) and *(OH)(OH), which, through hydrogen
bonding, induce spectator surface *H. This results in an onset potential
closely matching experimental values, in stark contrast to the traditional ORR
pathway, which keeps adsorbates intact and overestimates the onset potential by
0.7 V. Finally, we introduce electrochemical strain spectroscopy (ESS), a
groundbreaking strain analysis technique. ESS combines ab initio calculations
with experimental measurements to validate proposed reaction pathways and
pinpoint rate-limiting steps.

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