Abstract
Au−Pd nanocrystals are an intriguing system to study the integrated functions
of localized surface plasmon resonance (LSPR) and heterogeneous catalysis. Gold is both
durable and can harness incident light energy to enhance the catalytic activity of another
metal, such as Pd, via the SPR effect in bimetallic nanocrystals. Despite the superior catalytic
performance of icosahedral (IH) nanocrystals compared to alternate morphologies, the
controlled synthesis of alloy and core−shell IH is still greatly challenged by the disparate
reduction rates of metal precursors and lack of continuous epigrowth on multiply twinned
boundaries of such surfaces. Herein, we demonstrate a one-step strategy for the controlled
growth of monodisperse Au−Pd alloy and core−shell IH with terraced shells by turning an
ionic switch between [Br−]/[Cl−] in the coreduction process. The core−shell IH nanocrystals
contain AuPd alloy cores and ultrathin Pd shells (<2 nm). They not only display more than
double the activity of the commercial Pd catalysts in ethanol electrooxidation attributed to
monatomic step terraces but also show SPR-enhanced conversion of 4-nitrophenol. This strategy holds promise toward the
development of alternate bimetallic IH nanocrystals for electrochemical and plasmon-enhanced catalysis.
