INFLUENCE OF THE CONCENTRATION OF CTAB AND PHOTOCATALYST ON THE SIZE OF AU NANOTRIANGLES SYNTHESIZED BY A PHOTOCATALYTIC METHOD

Shape-controlled synthesis of Au nanoparticles has received considerable attention, mainly due to the interesting optical properties of anisotropic Au nanostrutures, namely a strong plasmon band in the NIR region. In particular, several methods for the preparation of Au nanoplates have been reported, including the use of plant extracts,1 seed mediated synthesis,2 use of polymers as capping agents,3 and thermal reduction.4 Nevertheless, the control over the size of the nanoplates is still a major challenge, with most of the methods yielding nanoplates with widhts from a few hundred nanometers to a few micrometers, and large size dispersion. We report a method for the preparation of Au nanoplates based on a photocatalytic approach5 to reduce the Au(III) precursor, in aqueous solution, in the presence of CTAB and a weak reducing agent. Changing the concentration of the photocatalyst it was possible to prepare samples with average side length 50 nm; 80 nm; 140 nm; and 250 nm (Fig. 1). Further control of the size of the nanotriangles can be achieved by changing the concentration of CTAB for each of the photocatalsyt concentrations used. For instance, it was possible to prepare nanotriangles with average size length of 90 nm, 65 nm, and 35 nm, by increasing the concentration of CTAB (Fig. 2). In order to further understand the mechanism of formation o