Pt-based bimetallic nanocrystals are feasible to dramatically improve the catalytic performances in fuel cells via morphology- and composition-engineering. Herein, bimetallic platinum(69)-cobalt(31) nanosheet nanoassemblies (Pt69Co31 NSNSs) were facilely synthesized through a one-pot co-reduction solvothermal strategy in oleylamine (OAm), using cetyltrimethylammonium chloride (CTAC) and allantoin as the directing agents. The current synthesis highly depended on the critical concentrations of Pt and Co precursors, the combined use of allantoin to OAm as the co-reductant, and the use of proper allantoin concentration. The obtained nanocatalyst exhibited largely enhanced electrocatalytic activity and durable ability towards ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) relative to home-made Pt85Co15 nanoparticles (NPs), Pt19Co81 NPs and Pt black catalysts due to its much larger electrochemically active surface area than the contrasts. (C) 2018 Elsevier Inc. All rights reserved.