Photodeposition of gold on titanium dioxide for photocatalytic phenol oxidation

The influence of experimental conditions during the photodeposition in the preparation of supported Au on TiO2 has been studied. Besides preparation pH, light intensity and deposition time showed to have a high influence on the final properties of gold deposits.Photodeposition using illumination with a high light intensity UV–vis lamp (140 W/m2 UVA range) resulted to be an ineffective method for obtaining nanoparticles of gold on the titania, producing very large and poorly distributed gold deposits. Thus obtained materials did not show any important improvement of their photocatalytic activity tested for phenol oxidation.By contrast, photodeposition using a low light intensity of illumination (0.15 W/m2 UVA range), produced materials with notably improved photocatalytic activity. The illumination with such a low light intensity allowed the control of the amount, aggregation and oxidation state of gold by changing deposition time, enabling a feasible method of tailoring Au–TiO2 with the appropriate properties for a high photocatalytic activity.Best photocatalytic behaviour for phenol photodegradation was obtained for Au–TiO2 samples prepared by photodeposition at low light intensity with 120 min photodeposition time for catalysts with a 0.5% and 1% nominal content of gold and with 60 min photodeposition time for catalyst with a 2% nominal content of gold.

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► Influence of photodeposition parameters on phenol photooxidation.
► Light intensity and deposition time high influence on gold deposits on TiO2.
► Low light intensity allowed a feasible method for Au–TiO2 with high photoactivity.