Facile synthesis of ultrathin Pt-Pd nanosheets for enhanced formic acid oxidation and oxygen reduction reaction

Two-dimensional metal nanosheets are usually synthesized by CO confinement methods. In this work, a diamine-assisted synthesis of ultrathin Pt-Pd alloy nanosheets is developed. Wrinkled Pt-Pd nanosheets of different compositions, with a size of up to 2 mu m and a thickness of only 2 nm, can be obtained via a one-pot solvothermal method. With a systematic study of ligand generality, aliphatic terminal diamine, diethylenetriamine, and in situ formed dimethylamine are shown to play vital roles in the formation of nanosheets. The ultrathin nature and the presence of Pt provide the alloy nanosheets with enhanced catalytic activity towards electrocatalytic reactions. In particular, the freestanding Pd19Pt1 nanosheet delivers activities of 1.831 A mg(metal)(-1) at 0.330 V vs. RHE in the formic acid oxidation and 6.65 A mg(Pt)(-1) at 0.9 V vs. RHE in the oxygen reduction reaction, significantly better than those of the standard Pt/C. This new synthetic strategy opens up a facile route to synthesize ultrathin Pt-alloy nanosheets, and has great potential for future development of catalysts.