Anion doping with fluorine to a durable ceria-based electrolyte

Pure/undoped ceria materials have attracted lots of interests for semiconductor membrane fuel cells (SMFCs) operated at reduced temperature, among of them, commercialized CeO2 in nano-scales exhibits an impressive transient electrical property with obvious high performance price ratio. Nevertheless, its excessive voltage attenuation rate and short circuit issues hinder the potential electrolyte application in low-temperature ceramic fuel cell. In this work, an innovative anion doping process is demonstrated to tune the commercialized CeO2 to a durable fluorine-doped ceria electrolyte, which is beyond the cation structural doping strategy usually utilized in ceria-based materials. Assembled with symmetrical NCAL electrode, the CeO2-y-δFy electrolyte succeed in a superior fuel cell properties with high open circuit voltage (OCV) and improved power density of 427.8 mW cm−2 at 550 °C. More importantly, compared to pure CeO2 electrolyte counterpart, the optimized fuel cell on fluorine-doped CeO2 (CeO2-y-δFy) electrolyte material exhibits a two-order reduction of attenuation rate of operative voltage at current density of 156 mA cm−2. The effects of fluorine doping on the morphology and structure of CeO2 and the electrochemical properties of semiconductor were proved by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. Fluorine doping modification is believed as a universal strategy for ceria-based and other nano metal oxide semiconductor MOS electrolyte materials.