Cerium Modified Copper Oxide Films for the Catalysis of the Oxygen Evolution Reaction

Abstract

Development of efficient and sustainable energy storage technologies is one of the most critical areas of contemporary research. Two energy storage technologies, solar water splitting and metal-air batteries, could disrupt the energy ecosystem in a sustainable way. One of the limiting factors of these technologies is the oxygen evolution reaction (OER) which is characterized by high overpotential and a complex reaction mechanism. In this study, electrodeposition methods for Cerium modified CuOx film synthesis are explored as a method for cheaper and scalable method for producing copper oxide based catalysts for OER. These films were deposited at potentials ranging from -2.5V to -4.0V from solutions with Cu to Ce molar ratios ranging from 100:0 to 40:60. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD) were employed to characterize the catalysts. OER performances were determined for these catalysts and analyzed to understand the impacts of film composition on OER catalysis. Electrodeposition was shown to favor CuO deposition and Ce incorporation at higher voltages and from solutions with higher Ce concentrations. While small quantities of Ce were effective in reducing onset potentials and maintaining high peak current densities of the catalyst, excessive incorporation of Ce into the catalyst resulted in significant CeO2 formation instead of the favored incorporation of trivalent Ce. Operando Raman was attempted to identify reaction mechanisms but the catalysts proved to be poor candidates for Operando Raman spectroscopy.