Colorimetric formaldehyde analysis can evaluate “true” photocatalytic activity induced by photoabsorption of a “photocatalyst” with high reliability compared with gas-chromatographic analyses.

The electron energy structures of TiO ₂ (B) and anatase were estimated by analyzing the energy-resolved distribution of electron traps.

An attempt to identify inorganic solids, such as metal oxides, using ERDT (energy-resolved distribution of electron traps)/CBB (conduction-band bottom) patterns, measured by reversed double-beam spectroscopy, as a “fingerprint” is introduced.

Facet-selective gold or platinum-nanoparticle deposition on decahedral-shaped anatase titania particles (DAPs) exposing {001} and {101} facets via photodeposition (PD) from metal-complex sources was reexamined using DAPs prepared with gas-phase reaction of titanium (IV) chloride and oxygen by quantitatively evaluating the area deposition density on {001} and {101} and comparing with the results of deposition from colloidal metal particles in the dark (CDD) or under photoirradiation (CDL). The observed facet selectivity, more or less {101} preferable, depended mainly on pH of the reaction suspensions and was almost non-selective at low pH regardless of the deposition method, PD or CDL, and the metal-source materials. Based on the results, the present authors propose that facet selectivity is attributable to surface charges (zeta potential) depending on the kind of facets, {001} and {101}, and pH of the reaction mixture and that this concept can explain the observed facet selectivity and possibly the reported facet selectivity without taking into account facet-selective reaction of photoexcited electrons and positive holes on {101} and {001} facets, respectively.