Award Sessions: Monday, April 18

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Monday, April 18 1:00 pm EST

SEAC – Charles N Reilley Award
Awardee: Paul Bohn, University of Notre Dame
Introduction: Carol Korzeniewski

Multifunctional Nanostructures for Electrochemistry of Single Atoms and Molecules
Electrochemical phenomena in nanostructures exhibit a range of unique characteristics not observed in larger structures. These range from unusual electron transport properties in atomic-scale metal junctions (quantum point contacts), to novel ionic screening, permselectivity, and concentration polarization effects on molecular transport, to coupling of nanophotonics with electrochemistry to enable single molecule spectroelectrochemical investigations. Atomic-scale junctions constructed from metallic nanowires, containing one or a few atoms in the transverse dimension, exhibit ballistic electron transport. They are fabricated by self-limiting electrochemical processes, and their conductance is extremely sensitive to surface adsorbates, with the power spectral density revealing dynamics associated with molecular surface dynamics, molecule-adatom complex formation and surface redox processes. Novel electrokinetic transport phenomena arise in nanoarchitectures with sizes commensurate with the Debye length. Nanostructures of this type, e.g. zero-dimensional nanopores, support enhanced electrochemical currents in the absence of supporting electrolyte; strong current amplification from nano-confined electrode pairs; and enhanced voltammetric sensitivity and selectivity. New possibilities for the study of single electron transfer events are opened by the use of bimodal nanoelectrochemical-nanophotonic structures, such as the electrochemical zero-mode waveguide. High density recessed dual-ring electrode nanopores can couple single electron-transfer events in fluorogenic redox species to changes in fluorescence emission which can then be used to follow the redox behavior of single ions and molecules.

SEAC – Royce W. Murray Award
Awardee: Justin Sambur, Colorado State University
Introduction: Carol Korzeniewski

Nanoscale Imaging of Electrochemical Energy Conversion and Storage Systems
Energy needs and environmental trends demand a large-scale transition to clean, renewable energy. Nanostructured materials are poised to play an important role in this transition. However, nanomaterials are chemically and structurally heterogeneous in size, shape, and surface structural features. My research group focuses on understanding the correlation between nanoparticle chemistry/structure and functional properties. The first part of my talk will focus on elucidating charge storage mechanisms in nanoscale materials, which underlies the performance of electrochemical technologies such as batteries and smart windows. I will discuss our high-throughput electro-optical imaging method that measures the battery-like and capacitive-like (i.e., pseudocapacitive) charge storage contributions in single metal oxide nanoparticles. I will present our recent single particle-level measurements that show (1) individual particles exhibit different charge storage mechanisms at the same applied potential and (2) particle size-dependent pseudocapacitive charge storage properties. The second part of my talk will focus on solar energy conversion using monolayer-thick (ML) two-dimensional (2D) materials such as MoS2 and WS2. ML semiconductors represent the ultimate miniaturization limit for lightweight and flexible power generation applications. However, the underlying solar energy conversion processes in 2D materials is not entirely understood. We developed a correlated laser reflection and scanning photocurrent microscopy approach to study how layer thickness and surface structural features (edges versus basal planes) influence solar energy conversion efficiency. I will highlight our photocurrent microscopy study that revealed how layer stacking order in heterojunction photoelectrodes influences charge separation, transport, and recombination pathways.

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