Inorganic and Materials Chemistry; Nanomaterials; Mechanochemistry; Surface and Colloid Chemistry
Whether they will be used in catalysis or artificial limbs, nanoparticle surfaces influence every aspect of their behavior. The ligand shell of a nanocrystal can determine its luminescence, its performance in a solar cell, or its clearance from the human body – to name just a few examples. In the Millstone group, we are interested in synthetically controlling this nanoparticle surface architecture – both the crystallographic and chemical composition – in order to develop new nanoparticle morphologies and reaction mechanisms that will have applications in fields ranging from catalysis to medicine.
Colloidal Nanoparticle Alloys: From bronze to steel, alloyed materials have defined the technological capabilities of their times, and like their monometallic counterparts, can experience dramatic changes in their physical properties at the nanoscale. Small, multimetallic nanoparticles (diameter = 1-5 nm) promise to provide improved catalysts for efficient use of fossil fuel resources as well as multifunctional tools in biomedical applications. However, current methods to prepare discrete, multimetallic particles afford limited tunability of particle composition, especially with respect to selectivity between alloyed, core-shell and Janus architectures. We use particle surface chemistry to control nanoparticle composition and elucidate both the synthesis and the resulting materials using a wide variety of electron microscopy and molecular characterization techniques.
Multifunctional Nanoparticle Synthesis: It is well known that the physical properties of nanoscale materials are highly dependent on their morphology. However, there is currently no systematic way to design and then rationally access a particular nanoparticle architecture. Elucidating these pathways would allow us to better use our current materials, and more effectively tailor new ones. Just as organic chemistry research has developed a mechanistic framework and synthetic toolbox that has produced everything from plastics to pharmaceuticals, so too must these concepts be developed for nanochemistry in order to harness the similar potential of nanomaterials. Through the discovery of nanoparticle reaction mechanisms, we work to develop a set of physical, analytical, and synthetic principles to rationally generate complex, highly-tailored nanoparticles for environmental remediation and catalysis applications.
Mechanochemistry of nanoparticles: At the nanoscale, the interplay between mechanical forces and physical properties is likely exaggerated compared to bulk materials. We are interested in understanding how mechanical forces can be used to manipulate the chemical reactivity of nanostructures. We will work to understand the response of anisotropic nanoparticles to mechanical stresses, and establish how mechanical perturbation can be used as a new type of synthetic tool in the development and application of nanomaterials.