Atomic force microscopic study on thermal and UV-irradiative formation and control of Au nano-particles on TiO2(110) from Au(PPh3)(NO3)

Abstract

Formation of Au nano-particles on TiO₂(110) from a gold–phosphine complex Au(PPh₃)(NO₃) was studied by environment-controlled atomic force microscopy (AFM). The Au complex began to agglomerate as particles larger than 4.2 nm in height on calcination in dry air at a temperature as low as 363 K. The size of the agglomerates reduced to 3.0 nm as a result of decomposition and combustion of the ligands by further calcination at 493 K for 4 h. UV irradiation of the Au-complex-deposited sample or of the TiO₂(110) substrate before deposition of the Au complex greatly reduced the size of the Au particles formed by the same calcination process to less than 1 nm, which falls in the range that has been claimed to show high catalytic activities for low-temperature CO oxidation. This may be a new preparation method that regulates the size of Au particles on flat oxide substrates.