Lawrence Adijanto

Exceptional thermal stability of Pd@CeO2 core-shell catalyst nanostructures grafted onto an oxide surface.

Monolayer films of highly catalytically active Pd@CeO2 core-shell nanocomposites were grafted onto a planar YSZ(100) (yttria-stabilized zirconia, YSZ) single crystal support that was functionalized with a CVD-deposited layer of triethoxy(octyl)silane (TEOOS). The resulting monolayer films were found to exhibit exceptionally high thermal stability compared to bare Pd nanoparticles with the Pd@CeO2 nanostructures remaining intact and highly dispersed upon calcining in air at temperatures in excess of 1000 K. The CeO2 shells were also shown to be more easily reduced than bulk CeO2, which may partially explain their unique activity as oxidation catalysts. The use of both TEOOS and tetradecylphosphonic acid (TDPA) as coupling agents for dispersing Pd@CeO2 core-shell nanocomposites onto a high surface area γ-Al2O3 support is also demonstrated.

Transition metal-doped rare earth vanadates: a regenerable catalytic material for SOFC anodes

The physical and electrochemical properties of cerium vandates in which a portion of the cerium cations have been substituted with transition metals (Ce1−xTMxVO4−0.5x, TM = Ni, Co, Cu) were investigated and their suitability for use in solid oxide fuel cell (SOFC) anodes was assessed. Similar to other transition metal doped perovskites, the metals were found to move out of and into the oxide lattice in response to exposure to reducing and oxidizing conditions at elevated temperatures. This process produces nanoparticle metal catalysts that decorate the surface of the conductive cerium vanadate. Solid oxide fuel cells (SOFC) with Ce1−xTMxVO3–YSZ composite anodes exhibited high electrochemical activity. It was also demonstrated that doping with the alkaline earth ions, Ca2+ and Sr2+ enhances the electronic conductivity of the vanadate and Ce0.7Sr0.1Ni0.2VO3–YSZ composite SOFC anodes were found to have both high electrochemical activity and unusually high redox stability.