TiO2 photocatalysts were prepared and coated on surfaces. Ultrathin TiO2 coatings were obtained by wash-coating and screen-printing techniques. The latter provides films of excellent adhesion that could tolerate washing under water jet. The scratch-proof coatings were characterized, and X-ray diffraction (XRD), atomic force microscopy (AFM) and N-2 physisorption indicated that the addition of polyethylene glycol (PEG) not only improved the coating properties of TiO2 but also served as poragen to produce high surface area, mesoporous TiO2. The coated TiO2 displayed better activity than the commercial P25 TiO2 for photocatalytic oxidation of ethylene, ethanol, acetaldehyde, isopropanol and acetone. The catalyst also exhibited excellent bactericidal, fungicidal and virucidal activities against a wide variety of Gram-positive and Gram-negative bacteria, fungal spores and T2 bacterial phage. A simple photoreactor with tangential air flow was designed and tested in a chamber, before incorporating in a prototype air purifier. The study showed that there is good agreement between laboratory catalyst reaction data (i.e., 110 mmol h(-1) for acetone) and the prototype test results (69 mmol h(-1)). (C) 2011 Published by Elsevier B.V.