(472e) Effects of Iron Doping of Cobalt Oxide Nanoparticles on Water Adsorption and Splitting

Energy generation and storage from clean and sustainable sources is one of the central challenges of the 21st century. Water splitting (2H₂O --> O₂ + 2H₂) is studied for its potential of being a carbon neutral, sustainable source for the simplest fuel H₂ when paired electrochemically with solar cells or another renewable energy source. The oxygen evolution reaction (OER) is the current bottleneck for this process and current state of the art catalyst are based on Ir and Ru, two metals that are rare and expensive. For economic viability, OER catalysts must be composed of abundant materials, such as Mn, Fe, Co, and Ni. Conveniently, mixed-metal oxides show increased activity as OER catalysts versus their unary oxide counterparts, but the reason for increase in catalytic activity is unknown [1]. Using well defined model systems combined with Density Functional Theory (DFT) investigation, we have studied the role of dopants in OER catalysts. Analysis of different sites of cobalt oxide nanoislands, with and without Fe, can provide information on the why binary oxides are better than their unary counterparts.

CoO_x and Fe-doped CoO_x nanoislands on Au(111) have been previously studied through experimental and theoretical methods in order to understand the role a dopant plays on structure and catalytic ability [2-4]. Bilayer and trilayer nanoislands of CoO_x have been synthesized and characterized by STM and other techniques giving unique insight into structural features that lead to good OER activity. DFT investigation of these nanoparticles on the basal planes and edges provides an understanding for the doping patterns and reactivity changes caused by Fe-doping. Atomic scale understanding of these model nanoisland systems provide valuable insight to the interplay between different oxide species in hydroxide/oxyhydroxide systems and aide in the design new, earth abundant catalysts for OER.

Keywords: water splitting, OER, cobalt oxide, oxyhydroxides

References

1. Zhang B, Zheng X, Voznyy O, Comin R, Bajdich M, et al. Science 352.6283 (2016): 3330337
2. Fester J, García-Melchor M, Walton AS, Bajdich M, Li Z, Lammich L, et al. Nat Commun 2017;8:14169. (2017)
3. Rodríguez-Fernández J, Sun Z, Zhang L, Tan T, Curto A, Fester J, Vojvodic A, Lauristen J. J Chem Phys. 150, 041731. (2019)
4. Curto A, Sun Z, Rodríguez-Fernández J, Zhang L, Parikh A, Tan T, Lauritsen J, Vojvodic A. Nano Res. (2019) 12: 2364. (2019)