Stearic acid

The photocatalytic activity of the deposited films was evaluated through the degradation of stearic acid under visible light irradiation. 52 A LOT-Oriel solar simulator with a 420 nm cut-off filter was used with a light intensity of 509 mW cm -2 [Caution: solar simulators are intense UV sources that can cause skin and eye damage]. In each experiment, a thin layer of stearic acid (98%, Fisher Scientific) was dip-coated onto the tantalum oxynitride film from a 0.05 M solution of stearic acid in dichloromethane (99.8%, Fisher Scientific). The amount of stearic acid deposited was quantified using FTIR, recorded using a Perkin Elmer 100 spectrometer over the range 2800 cm -1 to 3000 cm -1 , using the previously established relationship that 1 cm -1 of integrated peak intensity is equivalent to 9.7 × 10 15 molecules of stearic acid. 53 Once the stearic acid layer had been applied and quantified the sample was placed under the filtered solar simulator for exposure to visible light. The sample was then removed every 30 mins to monitor the photocatalytic degradation of the stearic acid layer, up to a total of 210 mins of exposure.