The surface geometry and elemental composition of electrocatalysts are known to be key factors to determine the kinetics of electrocatalytic reactions. We introduce the shape- and composition-controlled nanoscale electrocatalysts for acidic oxygen evolution and ammonia oxidation reactions. First, we synthesize the Pd@Ir nanocrystals with controlled surface geometry through the deposition of Ir atoms on the surface of freestanding Pd nanocubes in a liquid phase. In the 0.1 M HClO4 electrolyte, the synthesized Pd@Ir concave nanocubes show significantly enhanced oxygen evolution reaction activity compared to the IrO2 nanoparticles. We reveal that the improved activity of the Pd@Ir concave nanocube is mainly due to the well-controlled surface geometry based on high-index facets. In addition, we synthesize Pt−Ir alloy nanocube with controlled elemental composition as a high-performance electrocatalyst for ammonia oxidation reaction. The Pt-rich Pt−Ir alloy cubic nanocrystals exhibit significantly enhanced ammonia oxidation activity compared with commercial Pt/C nanoparticles. This remarkable improvement can be attributed to the optimized electronic structure of the surface atoms based on their controlled surface geometry as well as elemental composition.

Tailoring electro-oxidation kinetics by controlling the shape and composition of nano-scale electrocatalysts

256th National Meeting (2018)

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