Functional Materials

Photocatalytic Titanium Dioxide, ST/STS Series

Titanium Dioxide essentially exhibits strong photo activated oxidization when irradiated by UV ray.
The pigmented titanium dioxide for paints and plastics usually suppress the photo activity with the surface treatment. Photocatalytic titanium dioxide maximizes the essential photo activity.
Photo catalyst decomposes the organic pollutants and malodors into carbon dioxide and water by the photo activated oxidation. And it presents antiviral or antibacterial activity. It also induce the high water affinity by photo activated super-hydrophilicity, which generates anti-fogging, anti-stain, self-cleaning performance. Furthermore, the photo activated reaction is sustained as a regenerative action.
ISK's photocatalytic titanium dioxide ST, STS products was developed with our unique technology to strengthen the photo activity.

Visible Light Photocatalyst:MPT-623, STS-427

ISK has intended to use the photocatalyst indoors, and developed a photocatalytic powder, which can be activated by visible light like fluorescence light. (Developmental product: MPT-623). It is expected to perform the decomposition of malodors, antiviral and antibacterial activity indoors.

☆Antiviral activity test (BacteriophargeQβ)

【Test method】

Antiviral activity test (Photo catalyst)
Bacteriopharge(JIS R 1756)
Fluorescent lamp 500 lx, 4 hours
Sharp Cut Filter TypeB
Cut under 380nm

Photocatalyst: 0.15 g/m2

☆Antibacterial activity test (Staphylococcus aureus )

【Test method】

Antibacterial activity test (Photo cataylst)
Staphylococcus (JIS R 1752)
Fluorescent lamp 500 lx, 4 hours
Sharp Cut Filter TypeB
Cut under 380nm

Photocatalyst: 3.6 g/m2

※Aqueous dispersion STS-427 is also available.

UV Light Photocatalyst

UV Light Photocatalyst exhibits high photo activity, when it is used exterior under substantial UV light of Sunlight. It can be applied for the filter of air cleaner in combination with UV lamp.

Figure: Application areas of TiO2 photocatalysis

● Photocatalytic Powder ST Series

1. Characteristics of ST series

Various grades with different particle size and adsorption properties are available.

grades X-ray diameter(nm) SSA(m²/g) photoactivity characteristics
ST-01 7 300 highest photoactivity
ST-21 20 50 high photoactivity and dispersibility
ST-31 7 250 excellent gas absorption
ST-41 200 10 excellent dispersibility

2. Photocatalytic properties of ST series

・Gas phase (acetaldehyde)

Graph 1

amount of TiO2: 0.1g
light source intensity: black light 0.5mW/cm²
irradiation area: 24cm²
reaction volume: 2.8L

・Liquid phase (2-propanol)

Graph 2

amount of TiO2: 4g/L
light source intensity: black light 2mW/cm²
irradiation area: 24cm²
reaction volume: 80mL

● Photocatalytic Hydrosol STS Series

Acidic and neutral sols are available.

grade TiO2content (wt%) X-ray particle size (nm) pH characteristics
STS-01 30 7 1.5 acidic with nitric acid, excellent dispersibility
STS-02 30 7 1.5 acidic with hydrochloric acid, excellent dispersibility
STS-21 40 20 8.5 slightly basic and easy to handle

Photo-induced super-hydrophilicity

The surface coated with photocatalytic TiO2 shows super-hydrophilicity by UV irradiation. On the super-hydrophilic surface, adsorbed water does not form water drops but become thin layer. Thus, the surface exhibits anti-fogging effect and prevent the stain on the surface. Furthermore, the surface becomes easy to wash away a stain by water even if it adhered.
This phenomenon is called “photo-induced super-hydrophilicity” and draws an attention as new feature of a photocatalyst. It is used for various applications as below.

Figure: Mechanism of Superhydrophilicity

Figure: Applications ~Superhydrophilicity~