SusChEM: Insights into the Surface Chemistry of Water Oxidation on Pure and Modified Hematite Surfaces

Princeton University, Princeton NJ

Investigators

Abstract

SusChEM: Insights into the Surface Chemistry of Water Oxidation on Pure and Modified Hematite Surfaces Solutions for supplying sustainable energy, in particular our demand for fuels, will likely require developments in photoelectrocatalysis that enable us to go beyond only electricity generation. Hematite (iron oxide)-based materials are promising for water oxidation using sunlight, a reaction that currently limits performance in photoelectrocatalytic devices for generating hydrogen from water splitting or hydrocarbon fuel from carbon dioxide reduction. Iron oxide is an attractive photoelectrode material because it absorbs 40% of the solar spectrum, and is cheap, abundant, nontoxic, and stable against corrosion. Iron oxide is also very inefficient for energy conversion. This can be addressed by modifying the surface with other materials to improve performance. This project aims to develop a fundamental understanding of the surface chemistry of water oxidation on pure and modified hematite surfaces, which aid the development of new materials and future solar-driven photocatalytic devices. The work involves graduate and undergraduate students and postdoctoral research associates learning and collaborating on cutting-edge approaches in chemistry, surface science, and nanotechnology for discovering new catalysts and advancing sustainable energy production. The research results are integrated into undergraduate and graduate courses and undergraduate and K-12 educational outreach programs. With this award, the Chemical Catalysis Program of the Chemistry Division funds Dr. Bruce Koel of Princeton University to study the fundamental surface chemistry and processes associated with water oxidation on hematite (alpha-Fe2O3)-based photoanodes. The efficiency of this reaction must be increased to enable several transformative solar fuel production technologies to be utilized for future sustainable energy production. Iron oxide is attractive because of its solar absorption spectrum and abundance, but it is very inefficient. One strategy is to improve reaction kinetics and overpotentials by surface modifications with co-catalysts or by doping. Dr. Koel and his group establish composition-activity relationships on well-defined pure and modified single crystal alpha-Fe2O3 electrodes, with heteroatoms localized at the surface and subsurface. They also experimentally identify and characterize surface-bound species in order to investigate key aspects of the water oxidation mechanism. Measurements include using in operando techniques in which the electrode surface is probed during oxidation rate measurements. Insights provided by this work benefit the rational design of nanostructured catalysts and their applications in energy conversion. This is a Sustainable Chemistry, Engineering & Materials (SusChEM) proposal.