Nanoelectrics at Electrified Solid/Liquid Interfaces

In Operando Surface Potential Sensing of Photo-electrochemical Anodes

Get the latest solar water splitting research from the Boettcher group at University of Oregon, as well as Bruker’s recent Nanoelectrode probe and Data Cube developments.

Overview

We start with Mike covering interfacial charge transfer at the semiconductor-catalyst interface – an issue that is central for solar water splitting yet has been poorly understood. New insights require unique experimental approaches- such as using a nanoelectrode AFM-SECM probe, scanning the surface of at water splitting photoanode, and making local surface potential measurements, in operando. In this presentation, we will discuss fundamental aspects and capabilities of the probes used. 

We then show how the technique allows for measurement of the surface potential and thickness-dependent electronic properties of cobalt (oxy)hydroxide phosphate (CoPi). We show that when CoPi is deposited on illuminated photoanodes like hematite (a-Fe2O3), it acts as both a hole collector and an oxygen evolution catalyst. The versatility of the technique is highlighted by comparing surface potentials of CoPi-decorated hematite and bismuth vanadate photoelectrodes.

Following Mike’s presentation, Teddy provides an overview of Bruker’s new capabilities for nanoelectrical characterization in liquid. Nanoscale electrical measurements with AFM are common – in air, and extremely challenging in liquid. At Bruker we recently developed insulated nanoelectrode AFM-SECM tips, which enable first and only nanoscale electrical characterization in liquid by a commercial solution. In addition, we have also introduced an extensive set of new electrical Data Cube modes that provide an entire force and electrical spectrum at every pixel.

We show how the combination of these two innovations enables a whole range of new electrical measurements in liquid, including in situ piezoelectric response, conductivity, Kelvin Probe mapping, and benefits for research in solar water splitting. We show data addressing applications ranging from Li-ion batteries, electrocatalysis, to semiconductors and bioelectricity.

Dr. Teddy Huang 2

Dr. Teddy Huang is a Staff Applications Scientist at Bruker. He obtained his PhD degree in physical chemistry from Emory University in 2012. After graduation, he worked for Prof. Nathan Lewis at Caltech as a postdoctoral scholar, where he investigated the semiconductor/metal interfacial structure using AFM nanoelectric measurements. He joined in Bruker in 2014 and now leads the team for development of AFM-based electrical and electrochemical applications. As of today, he has published 43 peer-reviewed articles with more than 2300 citations and an H-index of 22.


About the Presenters

Michael Nellist PhD

Michael Nellist is a PhD student in Prof. Shannon Boettcher’s lab at the University of Oregon. His graduate work has been focused on better understanding the charge transfer processes that take place at the semiconductor-catalyst interface at photoanodes for water splitting. Michael earned his B.S. in Chemistry from SUNY Geneseo.