The Study On Mechanism Of Nanoscale Titanium Dioxied And Composites

In this article, the photocatalytic mechanism of titanium dioxide was studied, based on the applied experiments and the characterizations.The sample is composed of anatase and rutile; the ratio of rutile is 90%. Compared the structure of the sample is of core-shell which benefit to the evenly dispersion. The Raman spectrum shows that the titanium dioxide is short of oxygen. The absorption band of the sample is extended to visible light region, what' more, the absorption band in ultraviolet region is strong and wide. The shifts in absorption band is attributed to quantity-size effect, surface effect and small-sized effect.The study about antibacterial mechanism shows that nanoscale titanium dioxide use the strong oxide power of hole and the high activity of radicals in surface to kill the bacterial .The application of the titanium dioxide and its composites dedicated the antibacterial of titanium dioxide is indifferent to light source and can maintain long time and wide usage. The experiment also prove no matter in or on the surface, the titanium dioxide all can play antibacterial effect.The experiment of photodegradtion formaldehyde were carried out .the mechanism of photocatalytise was proved by the gas chromatogram and titration. The results showed that the sample can remarkable degrade formaldehyde, and the efficiency can reach to 94%. When the concentration of formaldehyde is low, the formaldehyde can be degraded to carbon dioxide and water. otherwise ,when the concentration is higher , formaldehyde can be degraded to firstly formic acid,then to carbon dioxide and water.The photocatalytic process includes the production of photo-induces electron-hole, the separation and combination, the production of active radicals, the attack to bacterial or organic. According to the energy-band structure and the surface states, the photocatalytic mechanism was analyzed. The rule of active radical was studied by electron spin resonance spectrum. Strong radical signs can be found under ultraviolet or visible light source. And even in dark we can also monitor the sign of active radical, which is the first report in the applied and research field of titanium dioxide.