Heat-transfer ('iron-on') photocatalytic films

The simple preparation of nanoparticulate CdS and TiO2 photocatalytic (PC) films embedded in a thin (2.5 μm) layer of polystyrene (PS), i.e. PC-PS films, is described. These CdS-PS, or TiO2-PS, films are then readily and easily transferred onto a range of different common flexible materials, such as many different plastics and fabrics, using the heat from an iron. In all cases the heat-transferred PC-PS films appear physically robust, as demonstrated by the 3 M Scotch Tape test, and, for the same PC, exhibit a similar photocatalytic activity, regardless of the material it is ironed onto. The photocatalytic activities of these iron-on films are demonstrated using cotton as the material support. Thus, the CdS-PS-Cot film is used to photoreduce methyl orange, methyl viologen and water using visible light (415 nm) and a sacrificial electron donor (ascorbate or EDTA). The TiO2-PS-Cot film is used to effect the same reduction reactions, but with UVA light (365 nm). The TiO2-PS-Cot film is also able to photocatalyse the oxidation of methylene blue and NO by air. In most cases there is little or no loss of activity with repeated use. Encouragingly, the non-optimised TiO2-PS-Cot film appears more active than the commercial flexible polymeric photocatalytic film Purify Mesh 30 (Taiyo Europe GmbH).