Optimizing Lattice Strain and Electron Effect of Ultrathin\nPlatinum Nanoshells through Core–Shell Construction toward\nSuperior Electrocatalytic Hydrogen Evolution

Abstract

For\noptimizing the lattice strain and electron effect of Pt catalysts\ntoward boosting their intrinsic electrocatalytic properties, we herein\nreport the building of ultrathin Pt nanoshells in subnanoscale on\nthe fine AgPd alloy cores, which are produced by alloying Pd atoms\ninto the Ag nanoparticles through galvanic replacement reaction (GRR).\nBecause of the smaller lattice expansion and modified electron effect\nof the ultrathin Pt shells in core–shell AgPd@Pt nanoparticles\nrelative to those in core–shell Ag@Pt counterparts, the <i>d</i>-band center of core–shell AgPd@Pt nanoparticles\nlocates at a lower position, favorable for weakening the adsorption\nof hydrogen and promoting their electrocatalysis for hydrogen evolution\nreaction (HER) in an acidic medium. Specifically, the core–shell\nAgPd@Pt nanoparticles with an appropriate Pt shell thickness not only\nshow the lowest overpotential of 15.8 mV at 10 mA cm^–2 in comparison with 27 mV of core–shell Ag@Pt nanoparticles,\nand 35 mV of commercial Pt/C catalyst, but also possesses the highest\nmass activity (1092.6 A g^–1) at the overpotential\nof 25 mV, which is 1.58 times higher than that of core–shell\nAg@Pt nanoparticles (693.5 A g^–1) and 6.74 times\nhigher than that of commercial Pt/C (162 A g^–1).\nMoreover, alloying Pd into Ag cores also endows the ultrathin Pt shells\nwith excellent electrocatalytic durability for HER. The concept of\nboth lattice strain and electronic engineering through a core–shell\nconstruction may provide guidance for designing other highly catalytic\nand cost-effective nanostructures for a myriad of electrochemical\nreactions.