(Invited) Plasmonic and Electrochemical Approaches to the Synthesis of Tailored Catalyst Materials

Abstract

The development of novel photo- and electrocatalytic processes requires the design of catalyst materials that are specifically optimized to take advantage of these driving forces. This talk will describe approaches developed in our lab for (1) using visible light stimulus to control the structure of plasmonically responsive and hybrid materials and (2) using electrodeposition to grow shape-controlled nanostructures on electrode surfaces. In the first case, the reduction of more catalytically active metals onto plasmonically active metals requires fine control over competing reductive and oxidative chemical processes. Differentially modulating the rates of these reactions using only chemical and thermal parameters can be prohibitively challenging. However, excitation of the plasmon resonance of the growing nanoparticles using visible light can yield hybrid structures that are not accessible via standard colloidal approaches. In the second case, while particles synthesized in colloidal solution can be processed and cast onto electrodes, this adds an additional fabrication step—increasing time and cost—and faces challenges in controlling particle dispersion on the surface. Meanwhile, direct chemical reduction-based synthesis of well-defined nanoparticles on electrodes has proven difficult. We have developed an integrated electrochemical approach that enables directed synthesis of shaped nanoparticles on electrode surfaces. Our approach links metal nanoparticle synthesis with real-time monitoring of chemical changes in the reaction solution using a combination of colloidal particle synthesis, electrochemical particle synthesis, and electrochemical measurements. This provides a pathway for the directed adaptation of the extensive library of existing shaped colloidal nanoparticle syntheses to growth on a surface—something that remains a non-trivial challenge.