Search for: All records

Abstract Here we show that just three electrochemical scans to modest positive potentials result in substantial growth of 1–2 nm Au dendrimer‐encapsulated nanoparticles (DENs). We examined two sizes of Au DENs, denoted as G6‐NH₂(Au₁₄₇) and G6‐NH₂(Au₅₅), where G6‐NH₂represents a sixth‐generation, amine‐terminated, poly(amidoamine) dendrimer and the subscripts, 147 and 55, represent the average number of atoms in each size of DENs.Ex situtransmission electron microscopy (TEM) andin situX‐ray absorption spectroscopy (XAS) results indicate that G6‐NH₂(Au₅₅) DENs grow to the same size as the G6‐NH₂(Au₁₄₇) DENs following these scans. Importantly, this growth occurs prior to the onset of detectable faradaic Au oxidation or reduction current. The observed growth in the size of the DENs directly correlates to changes in the electrocatalytic ORR activity. The key point is that after just three positive scans the G6‐NH₂(Au₁₄₇) and G6‐NH₂(Au₅₅) DENs are essentially indistinguishable in terms of both physical and electrocatalytic properties. 

Bimetallic nanoparticles remain a promising avenue to achieve highly reactive catalysts. In this contribution, we demonstrate the use of a photoswitchable peptide for the production of PdAu bimetallic nanoparticles at a variety of Pd : Au ratios. Using this peptide, the biomolecular overlayer structure can be switched between two different conformations ( cis vs. trans ) via light irradiation, thus accessing two different surface structures. The composition and arrangement of the materials was fully characterized, including atomic-level analyses, after which the reactivity of the bimetallic materials was explored using the reduction of 4-nitrophenol as a model system. Using these materials, it was demonstrated that the reactivity was maximized for the particles prepared at a Pd : Au ratio of 1 : 3 and with the peptide in the cis conformation. Such results present routes to a new generation of catalysts that could be remotely activated for on/off reactivity as a function of the ligand overlayer conformation.