Stability and Activity of Cobalt Antimonate for Oxygen Reduction in Strong Acid
Guided by computational Pourbaix screening and high-throughput experiments aimed at the development of precious-metal-free fuel cells, we investigate rutile CoSb₂O₆ as an electrocatalyst for oxygen reduction in 1 M sulfuric acid. Following 4 h of catalyst conditioning at 0.7 V vs RHE, operation at this potential for 20 h yielded an average current density of −0.17 mA cm⁻² with corrosion at a rate of 0.04 nm hour⁻¹ that is stoichiometric with catalyst composition. Surface Pourbaix analysis of the (111) surface identified partial H coverage under operating conditions. The Sb active site has an HO* binding free energy of 0.49 eV, which is near the peak of the kinetic 4e⁻ ORR volcano for transition-metal oxides in acidic conditions. The experimental demonstration of operational stability and computational identification of a reaction pathway with favorable energetics place rutile CoSb₂O₆ among the most promising precious-metal-free electrocatalysts for oxygen reduction in acidic media.
Additional Information© 2022 American Chemical Society. Received 8 December 2021. Accepted 14 February 2022. Published online 16 February 2022. This work was supported by Toyota Research Institute. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Author Contributions. L.Z. and H.L. contributed equally to this work. The authors declare no competing financial interest.
Supplemental Material - nz1c02673_si_001.pdf