Catalytic performance of Au/ZnO nanocatalysts for CO oxidation

ZnO prepared by chemical vapour deposition with gold loaded by ultrasonication was very active for CO oxidation. The unique catalyst–substrate interaction (epitaxy related) might be related with the results observed. Au was loaded (1% wt.) on three different ZnO supports, by three different methods: photodeposition, double impregnation and ultrasonication. Two commercial ZnO supports were used, along with a ZnO sample consisting of nanosized single crystals prepared by chemical vapour deposition. The samples were extensively characterised by various techniques. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with ZnO prepared by chemical vapour deposition with Au loaded by ultrasonication that showed an activity of 2 mol CO g Au - 1 h - 1 at room temperature. High-resolution electron microscopy images of the sample showed a number of gold nanocrystals epitaxially oriented on the ZnO rod. The unique catalyst–substrate interaction can be related to the increased catalytic activity of this sample, which was not observed for any of the others.