Layered cobalt oxides (Ca0.85-xYxOH)1.16CoO2 (x=0,0.05,0.1) were prepared by hydrothermal process and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The electrical conductivity and Seebeck coefficient were measured from 323 to 573 K.The XRD and SEM analysis showed that all samples were single phase with plate-like morphology.The substitution of trivalent Y for divalent Ca had a remarkable effect on the enhancement of electrical properties.The maximum PF value,9.17×10-5 W/(m·K2),was obtained for (Ca0.75Y0.1OH)1.16CoO2 at 573 K,indicating that they are promising thermoelectric materials for middle-temperature usage.
This review focused on rare-earth elements containing inorganic semiconductor photocatalysts for efficient solar energy conversion. We also summarized the recent progress in the modification of the transition metal oxides and mixed oxides with rare earth ions. In the first section, we surveyed a variety of rare-earth elements modified Ti O2 photocatalysts. Attributed to the modification with rare-earth elements, phase transformation of Ti O2 from anatase to rutile was inhibited. Furthermore, the light-absorbing property of the Ti O2 modified with rare-earth elements was also enhanced. In the second section, we summarized the effects of rare-earth elements on the modification of transition metal mixed oxides. It was believed that the corner-shared octahedral units in the form of networks, chains and slabs within the mixed oxide lattice were essential for the enhancement of the photocatalytic activity. In the last section, the strategy for the design of NIR or IR response upconversion composite photocatalysts was also discussed.
