A robust carbon tolerant anode for solid oxide fuel cells

Abstract

Solid oxide fuel cells (SOFCs) have been attracting remarkable attention as one of the most promising green energy conversion devices in the recent years. However, a high susceptibility of commonly used Ni-based anodes to carbon coking is a major challenge to the successful commercialization of SOFCs. In this study, a robust anode with Ni/TiO2−δ nano-network interfaces is reported, for low-cost SOFCs working at intermediate temperatures. This anode demonstrates an acceptable power density, and good stability with humidified (3% H2O) methane. X-ray diffraction (XRD) Rietveld refinement, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and high resolution transmission electron microscopy (HRTEM) images reveal that the Ni/TiO2−δ network-composite anode forms from the in-situ reductive decomposition of NiTiO3. Numerous Ni/TiO2−δ interfaces that facilitate the water adsorption and the water-mediated carbon-removing reactions form during this decomposition process. Density functional theory calculations predict that at the Ni/TiO2−δ interfaces, the dissociated OH from H2O (adsorbed on TiO2−δ) reacts with C (locating on Ni) to produce CO and H species, which are then electrochemically oxidized (combined with O2−) to CO2 and H2O at the triple-phase boundaries of the anode.