Generation of Enzymatic Hydrogen Peroxide to Accelerate the Etching of Silver Nanocrystals with Selectivity

We report a simple and versatile system for generating highly concentrated H2O2 on the surface of nanoparticles through enzymatic oxidation of glucose. It involves immobilization of glucose oxidase, a negatively charged enzyme, on the surface of a positively charged metal nanoparticle via electrostatic attraction. Upon the introduction of glucose at a concentration of 1.7 mM, this system is able to produce enzymatic H2O2 on the surface of the nanoparticle, with oxidation power equivalent to that of aqueous H2O2 at a concentration of 5 M when it is directly added into the reaction solution. We have evaluated the system for the etching of both twinned and single-crystal Ag nanocubes. We identified that the highly localized and concentrated H2O2 generated on the surfaces of Ag twinned cubes would lead to selective etching from the {111} facets parallel to the twin plane, in a fashion identical to the growth process but in the reversed order. For Ag single-crystals nanocubes, the etching would initiate from t...