Crystalline Control of {111} Bounded Pt₃Cu Nanocrystals: Multiply-Twinned Pt₃Cu Icosahedra with Enhanced Electrocatalytic Properties

Despite that different facets have distinct catalytic behavior, the important role of twin defects on enhancing the catalytic performance of metallic nanocrystals is largely unrevealed. The key challenge in demonstrating the importance of twin defects for catalysis is the extreme difficulties in creating nanostructures with the same exposed facets but tunable twin defects that are suitable for catalytic investigations. Herein, we show an efficient synthetic strategy to selectively synthesize {111}-terminated Pt₃Cu nanocrystals with controllable crystalline features. Two distinct {111}-bounded shapes, namely, multiply-twinned Pt₃Cu icosahedra and single-crystalline Pt₃Cu octahedra, are successfully prepared by simply changing the types of Cu precursors with the other growth parameters unchanged. Electrocatalytic studies show that the {111}-terminated Pt₃Cu nanocrystals exhibit the very interesting crystalline nature-dependent electrocatalytic activities toward both the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) with multiply-twinned Pt₃Cu icosahedra demonstrating enhanced electrocatalytic activities compared to the single-crystalline Pt₃Cu octahedra due to their additional yet important effect of twin defect. As a result, under the multiple tuning conditions (alloy, shape, and twin effects), the multiply-twinned Pt₃Cu icosahedra exhibit much enhanced electrocatalytic activities in both ORR and MOR with respect to the Pt black. The present work highlights the importance of twin defects in enhancing electrocatalytic activities of metallic nanocrystals