Effect of thermal treatments on the morphology, chemical state and lattice structure of gold nanoparticles deposited onto carbon structured monoliths

Gold nanoparticles (GNPs) were deposited onto carbon monoliths through direct chemical reduction of cationic gold sources. Colloidal gold particles were also deposited onto the same type of support to prepare a reference material. The Au/C structured materials were subjected to thermal treatment (annealing) up to 600 °C. Transformations in size, shape, chemical state and possible modifications in the lattice structure of GNPs due to thermal effects were evaluated by field emission gun (FEG), scanning electron microscopy (SEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). Evolution in size and shape of GNPs is compared with some of the models described in the bibliography for the melting of nanoparticles. No modification to either the lattice parameter or atomic structure in gold crystals was detected following annealing. The sintering process among gold nanoparticles could be observed in situ through HRTEM showing the aggregation mechanism for these particles.The financial support from Spanish Ministry of Science and Innovation (ref: ENE2011-23412) and European Regional Developments Funds. C. Gomez-Giménez thanks CSIC and European Regional Developments Funds for JAE grant.Peer reviewe