(60d) Connecting the in-Operando reduction Kinetics of Porous Nickel Oxide and Copper Oxide in Dilute H2 from the Molecular- to Micron-Scales for Clean Energy Generation

The kinetics of porous nickel and copper oxide reduction has applications that range from chemical looping combustion to solid oxide fuel cells. While previous studies reported the structural changes in materials independently of the microstructural evolution, we can simultaneously probe the microstructural and structural changes from the molecular- to micron-scales using multi-scale X-ray scattering (Ultra Small Angle/ Small Angle/ Wide Angle X-ray Scattering (USAXS/SAXS/WAXS)). By combining multi-scale X-ray scattering with X-ray Absorption Spectroscopy (XAS), it is now possible to connect the chemically-specific short-range changes in materials with the structural and microstructural changes across longer spatial scales. This in-operando experimental methodology is applied to contrast the reduction kinetics of nickel and copper oxides in dilute H₂ (~3%) at temperatures as high as 500^oC. The dynamic changes in the microstructure (i.e., porosity and particle size) of nickel and copper oxides as the materials are reduced are related to their corresponding structural changes.