When combined with controlled synthesis of well-defined facets and shapes, density functional theory (DFT) could give especially accurate descriptions of electrocatalytic reactions on surfaces. Dr. Adzic’s group has pioneered the controlled and uniform deposition of a monolayer (or overlayers) of Pt on a single crystal or nanoparticles of another transition metal or transition metal alloys.^1-6 Not only does this morphology achieve better utilization of the overlying Pt atoms, but the resulting structures also possess remarkable stability as electrocatalysts. Here, we review our long-standing collaboration with Dr. Adzic on the oxygen reduction reaction (ORR) over Pt monolayer or overlayers atop a variety of transition metals^5,7-12, as well as the electrooxidation of formic acid on Pt monolayers on single-crystals of transition metals. A logical extension of this methodology is to support Pt overlayers atop shape-selected nanoparticles, which selectively expose well-defined facets. Time-permitting, we will also be discussing insights from studying ORR of Pt overlayers on Pd icosahedra¹³, octahedra¹⁴, and nanocubes¹⁵. In several cases, the induced compressive strain and ligand effects that the Pt monolayer or overlayers experience on various substrates weaken the adsorption of oxygenated species (e.g.: OH) compared to pure Pt, thereby enhancing the ORR activity.

1. Zhang J, Mo Y, Vukmirovic MB, Klie R, Sasaki K, Adzic RR. Platinum monolayer electrocatalysts for O-2 reduction: Pt monolayer on Pd(111) and on carbon-supported Pd nanoparticles. J. Phys. Chem. B. Jul 29 2004;108(30):10955-10964.
2. Sasaki K, Naohara H, Cai Y, et al. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes. Angew. Chem. Int. Ed. 2010;49(46):8602-8607.
3. Adzic R. Platinum Monolayer Electrocatalysts: Tunable Activity, Stability, and Self-Healing Properties. Electrocatalysis. Dec 2012;3(3-4):163-169.
4. Bliznakov ST, Vukmirovic MB, Yang L, Sutter EA, Adzic RR. Pt Monolayer on Electrodeposited Pd Nanostructures: Advanced Cathode Catalysts for PEM Fuel Cells. Journal of the Electrochemical Society. 2012;159(9):F501-F506.
5. Knupp SL, Vukmirovic MB, Haldar P, Herron JA, Mavrikakis M, Adzic RR. Platinum Monolayer Electrocatalysts for O-2 Reduction: Pt Monolayer on Carbon-Supported PdIr Nanoparticles. Electrocatalysis. Dec 2010;1(4):213-223.
6. Sasaki K, Wang JX, Naohara H, et al. Recent advances in platinum monolayer electrocatalysts for oxygen reduction reaction: Scale-up synthesis, structure and activity of Pt shells on Pd cores. Electrochimica Acta. Mar 2010;55(8):2645-2652.
7. Yang L, Vukmirovic MB, Su D, et al. Tuning the Catalytic Activity of Ru@Pt Core-Shell Nanoparticles for the Oxygen Reduction Reaction by Varying the Shell Thickness. J. Phys. Chem. C. Jan 31 2013;117(4):1748-1753.
8. Herron JA, Jiao J, Hahn K, Peng G, Adzic RR, Mavrikakis M. Oxygen Reduction Reaction on Platinum-Terminated "Onion-structured" Alloy Catalysts. Electrocatal. Dec 2012;3(3-4):192-202.
9. Zhou W-P, Yang X, Vukmirovic MB, et al. Improving Electrocatalysts for O-2 Reduction by Fine-Tuning the Pt-Support Interaction: Pt Monolayer on the Surfaces of a Pd3Fe(111) Single-Crystal Alloy. J. Am. Chem. Soc. Sep 9 2009;131(35):12755-12762.
10. Vukmirovic MB, Zhang J, Sasaki K, et al. Platinum monolayer electrocatalysts for oxygen reduction. Electrochim. Acta. Jan 20 2007;52(6):2257-2263.
11. Adzic RR, Zhang J, Sasaki K, et al. Platinum monolayer fuel cell electrocatalysts. Topics in Catalysis. Dec 2007;46(3-4):249-262.
12. Zhang JL, Vukmirovic MB, Xu Y, Mavrikakis M, Adzic RR. Controlling the catalytic activity of platinum-monolayer electrocatalysts for oxygen reduction with different substrates. Angewandte Chemie-International Edition. 2005;44(14):2132-2135.
13. Wang X, Choi S-I, Roling LT, et al. Palladium-platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction. Nature Commun. Jul 2015;6.
14. Park J, Zhang L, Choi S-I, et al. Atomic Layer-by-Layer Deposition of Platinum on Palladium Octahedra for Enhanced Catalysts toward the Oxygen Reduction Reaction. Acs Nano. Mar 2015;9(3):2635-2647.
15. Xie S, Choi S-I, Lu N, et al. Atomic Layer-by-Layer Deposition of Pt on Pd Nanocubes for Catalysts with Enhanced Activity and Durability toward Oxygen Reduction. Nano Lett. Jun 2014;14(6):3570-3576.