Controlling NC-NC Interactions by Photoinduced NC Solvation Shell Manipulation
Assembly of superlattices (SLs) from nanocrystals (NCs) with typical long organic ligands is not optimal for potential optoelectronic applications due to the insulating nature of these ligands. On the other hand, assembly of NCs with semiconducting inorganic ligands into functional SLs is not efficient. Most of these NC systems have low-dielectric semiconducting cores, and get kinetically trapped in the self-assembly process, forming disordered structures. In this work, we aim to experimentally elucidate the solvation shell surrounding electrostatically stabilized nanocrystals (NCs) and its photoinduced response using state-of-the-art time-resolved wide-angle X-ray scattering (TR-WAXS) experiments and supporting methods. Doing so will enable us to describe whether and how photoexcitation can be used to controllably manipulate NC-NC interaction potentials to promote ordered self-assembly of colloidal NCs that will have enhanced electronic properties over conventional ones. These studies will also readily suggest strategies to overcome kinetic trapping in a wide range of other bottom-up self-assembled systems of importance for fabricating next-generation materials.
John Davis (JD) is a 2nd year Physical Chemistry PhD student working in Professor Naomi Ginsberg’s group. Before UC Berkeley, JD received his M.S. in Chemistry from the College of William and Mary and his B.S. in Chemistry from Washington and Lee University. Spanning the interface of physics, chemistry, and materials science, JD’s research focuses on resolving and manipulating complex material formation on the nanoscale.
Operando Methods for the Characterization of Electrocatalyst
Small copper nanoparticles capped by tetradecylphosphonic acid ligands catalyze the electroreduction of CO2 to multicarbon products at low overpotentials. The extensive restructuring they undergo during the reaction calls for operando methods to better understand the nature of this catalyst. Electrochemical scanning transmission electron microscopy (EC-STEM) allows for imaging of the active catalyst to obtain morphological information, while X-ray spectroscopy gives complementary insights into the oxidation states and coordination environment. Together, these techniques allow us to paint a clear picture of the catalysts active state.
Julian is currently a 4th year graduate chemistry student with Prof. Peidong Yang, focusing on electrocatalytic CO2 conversion. Specifically, he synthesizes novel nanomaterials and tries to understand their distinct performances with the help of X-ray spectroscopy and liquid-cell electron microscopy. He obtained his B.S. and M.S. in Chemistry from the University of Munich, Germany.