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

Formation of Au nano-particles on TiO2(110) from a gold-phosphine complex A u(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 s ize 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 irrad iation of the Au-complex-deposited sample or of the TiO2(110) substrate bef ore deposition of the An complex greatly reduced the size of the Au particl es 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 regulat es the size of Au particles on flat oxide substrates.