PHOTOELECTROCHEMISTRY OF QUANTIZED WO3 COLLOIDS - ELECTRON STORAGE, ELECTROCHROMIC, AND PHOTOELECTROCHROMIC EFFECTS

Electro storage effects in quantized WO3 colloids have been investigat ed by spectroelectrochemical and photochemical methods. Electrons trap ped within the colloidal particles exhibit blue coloration with absorp tion in the red-IR region. From picosecond laser flash photolysis expe riments, we estimate the rate constant for electron trapping to be 10( 10) s-1. These trapped electrons are stable in an inert atmosphere and can be utilized to reduce substrates such as thiazine and oxazine dye s which have reduction potentials less negative than the conduction ba nd Of WO3. The rate constants for the heterogeneous electron transfer at the semiconductor/electrolyte interface are in the range (0.7-2.4) X 10(9) M-1 s-1.