Size control of titanium oxide sheets by regulating catalysis in a catalytic sol-gel process and their UV absorption properties

Catalysis in a sol-gel process of titanium alkoxide was switched off to con trol the size of sheetlike particles of a resulting titanium oxide. The oxi de growth was suspended by adding acetic acid, which regulated the catalyti c activity of ammonium acetate. An ultraviolet-visible absorption band depe nded on the size of sheetlike particles. A lower energy region appeared for the larger size (> 1 mu m) of sheetlike particles but not for the smaller one. It is probably due to a bridging bidentate of acetate on the flat surf ace of titanium oxide particles.