Microstructured Au/TiO2 model catalyst systems.
The preparation of microstructured Au/TiO2 model catalysts as a first step toward micrometer-scale parallel studies on model catalysts and toward studies of mesoscopic effects in catalytic reactions was investigated by atomic force microscopy and X-ray photoelectron spectroscopy. The model systems, which consist of micrometer-size active areas covered with Au nanoparticles that are separated by similarly sized inactive areas free of Au particles, are fabricated by combining optical lithography methods for microstructuring and ultrahigh vacuum evaporation for Au nanoparticle deposition and by applying suitable cleaning steps. It is demonstrated that practically perfect microstructures with Au nanoparticles of catalytically relevant sizes (2-3-nm diameter) on a clean TiO2 substrate can be produced this way and that the processing steps do not affect the deposited Au nanoparticles, neither in size nor in lateral distribution.