The Simulation And Design Of Highly Activie And Stabile Anode Catalysts Of Solid Oxide Fuel Cells

Solid oxide fuel cells?SOFCs?are electrochemical devices that convert chemical energy into electrical energy.SOFC is expected to be a crucial technology in future power generation with many desirable advantages,such as high efficiency,fuel adaptability,all-solid state components,modular assembly,and low pollution.Many fuels,e.g.,hydrogen,natural gas,ethanol or hydrocarbon mixtures can be used in SOFC,which highlights the capability of SOFC as candidates for applications in stationary power generation.The dissociation of oxygen is an important step in several heterogeneous oxidation reactions due to its importance for CO oxidation and methanol oxidation reactions.The Ni/YSZ?yttrium-stabilized zirconia?cermet is the most popular anode material in SOFCs.In the Ni/YSZ cermet,the electronic conductivity is provided by Ni while YSZ provides the oxygen-ion conduction.The stability of the Ni/YSZ,the adsorption and dissociation of O₂ on the supported small nickel clusters and the catalytic reactivity of single noble metals?NMs?are systematically investigated using ab initio density functional theory calculations with the particular focus on the influence of the surface oxygen vacancy?Ov?.Our main works and results are summerized as below:1.The adsorption and dissociation of O₂ on the bare and Ni clusters adsorbed YSZ?111?surfaces with various number of Ni atoms are investigated.The dissociation of O₂ on the YSZ?111?surface is largely enhanced by the supported Ni dimer,which is predicted to be the smallest Ni cluster needed for efficient O₂dissociation.Hence,Ni₂/YSZ?111?system is the promising candidate for the low-temperature dissociation of O₂ with low cost and high activity.2.The adsorption of Au dimer on the MgO?100?,CaO?100?,Ba O?100?,TiO₂?110?and YSZ?111?surfaces is comparatively studied.It is found that Au dimer prefers upright adsorption mode on the MgO?100?,CaO?100?,BaO?100?surfaces and parallel adsorption mode on the TiO₂?110?and YSZ?111?surfaces.Based on the analysis of the adhesion energy and cohesive energy,we concluded that the Au adatoms are more likely to grow into 2D cluster on the BaO?100?and TiO₂?110?surfaces,but 3D cluster on the MgO?100?,CaO?100?and YSZ?111?surfaces.3.The structural stability and catalytic reactivity of single noble metal?NM??NM=Pd,Pt,Rh and Ir?atom supported on YSZ are systematically investigated.The Ir/YSZ?111?and Pt/YSZ-Ov?111?are testified as the most stable ones among the NM/YSZ?111?and NM/YSZ-Ov?111?systems,respectively.To further explore their activity and the role of the surface oxygen vacancy,the adsorption and dissociation of O₂ on Ir/YSZ?111?and Pt/YSZ-Ov?111?are studied and compared.Our results showed that the Pt/YSZ-Ov?111?exhibits high stability and reactivity for activating O₂ molecule,which may be a good ORR catalyst.