the removal of loosely bound oxygen on the swnt surface that provides p type doping of the semiconducting swnts in air in contrast the swnt pt 0 8 u03bcmol film exhibits a substantial 44 current increase which likely results from doping induced by platinum catalyzed atomic hydrogen the relative resistance drop for the swnt pt nanocomposites increases with platinum content fig5 b the electrocatalytic activity of the swnt pt nanocomposites are tested by cyclic voltammetry fig7 for potentials exceeding 0 4 v the peaks involving hydroxyl reactions show similar performance for both the swnt and swnt pt nanocomposite films while the double layer current rises for the swnt pt nanocomposite presumably due to the increase of film thickness in contrast the peak near u2212 0 1 v that describes hydrogen adsorption rises with the addition of platinum the active surface area of the platinum can be calculated by comparing the charge involved during hydrogen reaction shaded area in fig7 to the known charge per unit area for platinum 210 u03bcc cm 2 from this calculation the electrochemically active surface area for the swnt pt 0 8 u03bcmols nanocomposite is 23 6 m 2 g which is much larger than the value for bulk platinum 2 8 m 2 g and comparable to previous reports for carbon supported platinum 10 taking into account the average platinum nanoparticle diameter and the total platinum surface area 8 75 cm 2 42 of the platinum nanoparticle surface area is catalytically active use of platinum cnt nanocomposites as a cathode in dye sensitized solar cells in another embodiment of the present invention the film of nanocomposites of cnts and pt nanoparticles made by the method described in example 1 or a method similar to it 39 was tested.