Electrodeposition of shaped PtIr alloy nanocrystals with high–index facets for the electro–catalytic oxidation of alcohols

• The PtIr alloy nanocrystals with high-index facets were prepared by electrodeposition. • For the first time, the shape transformation of PtIr alloy nanocrystals from TOH to THH nanocrystals was realized. • The PtIr THH nanocrystals exhibited excellent electrocatalytic performance for polyol oxidation. Pt–group metal nanocatalysts enclosed with high–index facets have sufficient kink and step atoms on the surface, which could act as efficient sites for fuel cell reactions. Besides surface structure, alloying was another efficient strategy to obtain nanoparticles with excellent catalytic performance. So how about combining the surface structure of high–index facet with alloying to prepare Pt–based nanocatalysts? In this work, we have synthesized alloyed PtIr tetrahexahedral (THH) nanocrystals (NCs) with high–index facets (730) by electrodeposition. And PtIr trioctahedral (TOH) NCs with high–index facets (441) could be obtained by simply decreasing the upper limit potential (E U ) of square–wave potential (SWP) with other condition keeping the same as that for the synthesis of PtIr THH NCs. The successful synthesis of alloyed PtIr NCs with high–index facets mainly lied in the repetitive adsorption/desorption of oxygenated species on the surface of nanoparticles. The prepared PtIr THH NCs exhibited excellent electrocatalytic activity and stability towards ethylene glycol oxidation reaction (EGOR) and glycerol oxidation reaction (GOR). Among the nano–catalysts, the peak in the forward scan of PtIr THH NCs for EGOR and GOR were 19.9 mA∙cm −2 and 17.6 mA∙cm −2 , respectively, which were 9.5 and 6.8 times higher than those of commercial Pt/C. The excellent electro–catalytic performance of alloyed PtIr NCs could mainly be attributed to the surface structure effect of high–index facets and synergetic effect of the alloy structure. This work could provide a new idea for designing highly efficient nanocatalysts for fuel cells by combing surface structure effect and alloying effect together.