Evaluating H-2O Electrolysis on Ceria with Thin-Film Electrodes

摘要

Undoped ceria with its facile redox at high-temperatures has potential as an effective material for electrolysis. This study explores the electrochemical performance of thin-film ceria electrodes for H-2O electrolysis at 700 ℃. The electrochemical characterization is complemented by in situ XPS measurements, which show that the highly reduced ceria surface increases in degree of reduction with electrolysis voltage. Results also show that H-2O electrolysis is enhanced with increased H-2 partial pressure. Analysis of electrochemical impedance spectra and voltammetric measurements show that the electrolysis reactions depend strongly on H-2 pressure. These trends, which are not readily explained by simple surface kinetic models, do indicate that increased ceria surface reduction by the presence of H-2 product enhances activity for H-2O electrolysis. The results were used to create a microkinetic model to assess surface and subsurface processes in ceria for H-2O electrolysis.