Enhanced optical limiting of solubilized carbon nanotubesdecorated with Pt/Pd nanoparticles

We report here the nonlinear optical response of Solubilized Multiwalled Carbon Nanotubes (MWNTs) and these decorated with Platinum and Palladium Nanoparticles. Pristine MWNTs were functionalized with COOH group through microwave assisted synthesis route which rendered them soluble in water and other solvents too. Metal salts of Platinum and Palladium were further reduced to metal nanoparticles in presence of MWNT-COOH under microwave irradiation. These hybrid metal decorated carbon nanostructures were morphologically and functionally well characterized using SEM, EDAX, FTIR, UV-Visible etc., Using Z-scan technique, we carried out nonlinear optical studies on aqueous dispersions (stable) of these metal decorated (Pt/Pd-MWNT-COOH) using a high power Nd:YAG Laser with 532 nm excitation with 10 nanosecond pulse width. These samples exhibited significant nonlinear absorption and scattering. The metal decorated MWNT-COOH (Pt-MWNT-COOH:2 Jcm^-2; Pd-MWNT-COOH: 1.7Jcm^-2) exhibited enhanced optical limiting which is more than plain MWNT-COOH samples and similar Metal-Graphene hybrid dispersions reported earlier in literature. These could be ideally suited for optical power limiting applications.