Identification of Three Coexistent Defect Types in Hematite Photoanodes through Structure–Property Analysis

Abstract

Structural defects present in hematite photoanodes are analyzed by correlating parameters derived from Raman spectra, band structure measurements and photoelectrochemical (PEC) oxygen evolution reaction performance. A series of photoanodes with varying quality of hematite are prepared by sintering akaganeite films with a systematically varied protocol. Data acquired through Raman microscopy, linear sweep voltammetry, and electrochemical impedance spectroscopy is parametrized and systematically compared to detect relationships amongst the data. Correlations between the structural information contained within the Raman spectra and PEC parameters enable the identification of three types of structural defects within the material. Each defect type is found to exert unique influence on PEC behavior and each became dominant under specific fabrication conditions. A straightforward approach to detecting defects in photoelectrodes and identifying their influence on photoelectrode properties and behavior is provided.