Solid-State Chemistry of Photoelectrodes for Water Photoelectrolysis. Annual Report August 1983-September 1984

摘要

The author previously reported that donor-doped TiO2 and SrTiO3 have different defect structures that seem to be related to their differences in photoresponse. SrTiO3 exhibited bandgap reduction while TiO2 did not. A perovskite analogue, SrZrO3, without variable valent cations was studied to elucidate the different mechanisms of donor-dopant compensation and photoresponse. The solubility limit of lanthanum was established and the defect structures of both pure and donor-doped SrZrO3 were determined. Electrical conductivity, thermogravimetric, chemical and interdiffusion, and Raman spectroscopic measurements were used to determine the electronic and ionic defect compensation mechanisms. Both the composition and the crystal structure of heterogeneous catalysts are important in determining their activity, efficiency and specificity. The anatase polymorph of TiO2 is critical for efficient photolysis of water and the irreversible transformation to rutile occurs at relatively modest temperatures. They have used Raman spectroscopy to determine that rutile can be stabilized at temperatures below 450 C. The phase transformation from anatase to rutile was shown to be a function of both impurity type and concentration as well as ambient oxygen activity.