Gold (1 wt.%) was loaded on several carbon materials, namely, polymer based carbon xerogel, activated carbon, microdiamonds, nanodiamonds, graphite and silicon carbide by double impregnation and sol immobilisation. The obtained catalysts were characterised by N₂ adsorption at -196 ºC, high-resolution transmission electron microscopy, high-angle annular dark-field imaging (Z-contrast), temperature programmed desorption, atomic absorption spectroscopy and X-ray photoelectron spectroscopy. The obtained materials were tested on the microwave-assisted solvent-free oxidation of 1-phenylethanol by tert-butyl hydroperoxide (TBHP) to produce acetophenone. The results showed that the catalytic activity was influenced by several factors, namely, the nature of the support, reaction time and temperature, amount of catalyst, presence of additives, among others. The best values for acetophenone yield (99.9%) were obtained with Au deposited on microdiamonds by the colloidal method. Catalyst recyclability was tested up to six consecutive cycles at the optimized conditions for each catalyst, and it was found that Au on microdiamonds, prepared by the colloidal method, also maintained higher activity after several reaction cycles as compared to the other carbon supports.

The C-scorpionate iron(II) complex [FeCl₂(Tpm)] [Tpm=κ³-HC(C₃H₃N₂)₃] (1) was immobilized on five different nanostructured carbon materials (nanodiamonds, graphene nanoplatelets, graphene oxide, reduced graphene oxide, and nanohorns) to produce active, selective, and recyclable catalysts for alkane and alcohol oxidations. The heterogenized systems (including the first ever reported complexes supported on carbon nanohorns) exhibited good activity concomitant with rather high selectivity to the formation of ketone alcohol (KA) oil (cyclohexanol and cyclohexanone mixture, yields up to 29%) from microwave-assisted oxidation of cyclohexane, and allowed their easy recovery and reuse, at least for five consecutive cycles maintaining 90.3% of the initial activity. Moreover, the functionalized nanodiamond supports (used for the first time as supports for iron complexes) were also able to effectively (yields up to 97%) catalyze the microwave-induced oxidation of 1- and 2-phenylethanol to acetophenone and 2-phenylacetaldehyde, respectively, and could be reused for seven consecutive cycles without losing catalytic activity.