Rutile Alloys in the Mn–Sb–O System Stabilize Mn 3+ To Enable Oxygen Evolution in Strong Acid

Rutile Alloys in the Mn–Sb–O System Stabilize Mn 3+ To Enable Oxygen Evolution in Strong Acid

TitleRutile Alloys in the Mn–Sb–O System Stabilize Mn 3+ To Enable Oxygen Evolution in Strong Acid
Publication TypeJournal Article
Year of Publication2018
AuthorsLan Zhou, Aniketa Shinde, Joseph H Montoya, Arunima K Singh, Sheraz Gul, Junko Yano, Yifan Ye, Ethan J Crumlin, Matthias H Richter, Jason K Coope, Helge S Stein, Joel A Haber, Kristin A Persson, John M Gregoire
JournalACS Catalysis
Volume8
Issue12
Pagination10938 - 10948
Date Published10/2018
ISSN2155-5435
Abstract

Electrocatalysis of the oxygen evolution reaction is central to several energy technologies including electrolyzers, solar fuel generators, and air-breathing batteries. Strong acid electrolytes are desirable for many implementations of these technologies, although the deployment of such device designs is often hampered by the lack of non-precious-metal oxygen evolution electrocatalysts, with Ir-based oxides comprising the only known catalysts that exhibit stable activity at low overpotential. During our exploration of the Mn–Sb–O system for precious-metal-free electrocatalysts, we discovered that Mn can be incorporated into the rutile oxide structure at much higher concentrations than previously known, and that these Mn-rich rutile alloys exhibit great catalytic activity with current densities exceeding 50 mA cm–2 at 0.58 V overpotential and catalysis onset at 0.3 V overpotential. While this activity does not surpass that of IrO2, Pourbaix analysis reveals that the Mn–Sb rutile oxide alloys have the same or better thermodynamic stability under operational conditions. By combining combinatorial composition, structure, and activity mapping with synchrotron X-ray absorption measurements and first-principles materials chemistry calculations, we provide a comprehensive understanding of these oxide alloys and identify the critical role of Sb in stabilizing the trivalent Mn octahedra that have been shown to be effective oxygen evolution reaction (OER) catalysts.

DOI10.1021/acscatal.8b02689
Short TitleACS Catal.
Refereed DesignationRefereed