Facile Synthesis Of Carbon Supported Pd3au@Super-Thin Pt Core/Shell Electrocatalyst With A Remarkable Activity For Oxygen Reduction

Aiming at developing a highly active electrocatalyst with high platinum utilization efficiency, we report a facile synthesis of carbon supported Pd3Au@Pt electrocatalyst by chemical reduction of K2PtCl4, K2PdCl4, and aq NaAuCl4 with ascorbic acid (AA) under ambient conditions in the absence of surfactants. The resultant Pd3Au@Pt/C electrocatalyst comprises of a thin platinum layer less than 1 nm in thickness deposited on the outer surface of Pd3Au alloy core with an average diameter of 3.4 nm. Remarkably, Pd3Au@Pt/C exhibited a high mass activity (MA, 939 mAmg(Pt)(-1)) toward oxygen reduction reaction (ORR), which is 4.6 times that of commercial Pt/C (203 mAmg(Pt)(-1)). The durability of Pd3Au@Pt/C is close to that of commercial Pt/C. According to X-ray diffraction (XRD) patterns, the lattice constant of the Pd3Au alloy supported on carbon is determined to be 3.950 angstrom close to yet slightly larger than that of Pt/C (3.920 angstrom), inducing a lateral tensile strain of the platinum shell. Meanwhile, electrons from the Pd3Au core appear transferred to the platinum shell as evidenced by X-ray photoelectron spectroscopy (XPS). We propose that the lateral tensile strain (geometric effect) and the electron transfer (electronic effect) as well as the high platinum utilization efficiency have contributed to the significantly improved electrocatalytic activity of Pd3Au@Pt/C. The coexistence of the lateral tensile strain and the electron transfer in the electrocatalyst with a high ORR activity has not been reported prior to this study.