The photocatalytic destruction of methyl orange in aqueous solution has been studied over single crystal ZnO surfaces under UV irradiation. Differences in the apparent reaction rates between the polar surfaces (first order) and the nonpolar ZnO(10-10) surface (zero order) were observed. Reaction rates for different crystallographic orientations showed the highest activity for ZnO(10-10) followed by ZnO(0001)-Zn and the lowest activity for ZnO(000-1)-O surfaces. In addition, the etching of surfaces by photolysis has been studied. For this process, strongly face-dependent behavior was also observed. Possible reasons for the face dependencies are discussed.

No abstract

Enhancement of magnetocaloric effect (MCE) in nanostructured materials is important for refrigeration applications such as spot cooling in microelectromechanical system devices. Here we report the first investigation of MCE properties in ball-milled ZnFe2O4 particles. The MCE was obtained by measuring a family of M-H curves at set temperature intervals and calculating the entropy change (ΔS) for this system using the Maxwell relation. The surface structure of zinc ferrite particles is sensitive to ball milling conditions and we observed that these surface effects greatly impact the MCE and our observations could provide a route for its potential enhancement by controlled surface modification.