Abstract
The triple phase boundary (TPB), where the gas phase, Ni particles and the yttria-stabilised zirconia (YSZ) surface meet, plays a significant role in the performance of solid oxide fuel cells (SOFC). Indeed, the key reactions take place at the TPB, where molecules such as H2O, CO2 and CO interact and react. We have systematically studied the interaction of H2O, CO2 and CO with the dominant surfaces of four materials that are relevant to SOFC, i.e. ZrO2(111), Ni/ZrO2(111), YSZ(111) and Ni/YSZ(111) of cubic ZrO2 stabilized with 9% of yttria (Y2O3). The study employed spin polarized density functional theory (DFT), taking into account the long-range dispersion forces. We have investigated up to five initial adsorption sites for the three molecules and have identified the geometries and electronic structures of the most stable adsorption configurations. We have also analysed the vibrational modes of the three molecules in the gas phase and compared them with the adsorbed molecules. A decrease of the wavenumbers of the vibrational modes for the three adsorbed molecules was observed, confirming the influence of the surface on the molecules' intra-molecular bonds. These results are in line with the important role of Ni in this system, in particular for the CO adsorption and activation.
Highlights
The solid oxide fuel cell (SOFC) is an electrochemical device that converts electricity by oxidizing fuel, e.g. hydrogen, through an environmentally sustainable process [1]
A common anode used for this device is yttria-stabilized zirconia (YSZ) with supported Ni particles
The dissociative water adsorption on ZrO2 was observed in a previous investigation by Korhonen et al [39], where they showed experimentally and theoretically that water, at low coverage, dissociates on the monoclinic zirconia surface
Summary
The solid oxide fuel cell (SOFC) is an electrochemical device that converts electricity by oxidizing fuel, e.g. hydrogen, through an environmentally sustainable process [1]. Several experimental and theoretical studies of the Ni/YSZ cermet have endeavoured to gain understanding of the microstructure of this material, since the material's atomic level structure and processes lie at the core of the performance of the SOFC anode [5]. In the CO oxidation on Ni/YSZ, CO adsorbs associatively on Ni and diffuses towards the triple phase boundary (TPB), where the gas phase, Ni particles and YSZ surface meet. It is oxidized by O2– coming from the electrolyte i.e. the solid oxide (reaction (R.2)) [9]. We have elucidated the geometries and electronic structures of the most stable adsorption sites and compared these results with other reported computational models, where available, and supported our findings by experimental and computational infrared spectra (IR)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
