Zone-Specific Crystallization and a Porosity-Directed Scaling Marker for the Catalytic Efficacy of Au-Ag Alloy Nanoparticles

Abstract

Bimetallic Au-Ag hollow nanoprisms (HNPrs) with variable effective surface areas, dynamic atomic compositions (Au:Ag), and distinct stepped surfaces between the central porous region and crystalline periphery are synthesized through a modified seed-mediated growth followed by a sacrificial galvanic replacement method. Porous central-cavity-induced distortion from prism to disk shape generates an increased number of numerous low-coordinated crystal defects on the crystalline nanodisk surface along with extended d-orbital spacing of the respective crystal disorders in the central-cavity region of HNPrs to control their adsorption efficiency for different redox reactions. Among the different HNPrs, HNPr250 possesses the highest density of the grain boundary with a preferable Au:Ag ratio to form an extensive porous ligamentous central cavity, acts as a superior electrocatalyst to accelerate the kinetics of the uric acid (UA) oxidation (8.4 times compared to the blank electrode), and allows us to detect UA even in the nanomolar range. Experimental observations have been supported by density functional theory calculation to approximate the effective Au-Au displacement with a suitable percentage of Ag in different HNPrs to explain their measured catalytic activity. Copyright © 2019 American Chemical Society.