Sunlight driven decomposition of toxic organic compound, coumarin, p-nitrophenol, and photo reduction of Cr(VI) ions, using a bridge structure of Au@CNT@TiO2 nanocomposite

Abstract Au@CNT@TiO2 nanocomposite performed as an effective catalyst for the degradation of toxic organic dyes, reduction of p-nitrophenol to p-aminophenol, coumarin molecule to 7-hydroxycoumarin and for the removal of toxic ions Cr(VI). The local volumetric rate of photon absorption and total rate of photon absorption was calculated for quantitative confirmation of the photocatalytic activities. The total rate of photon absorption for Au@CNT@TiO2 and Au@TiO2 nanocomposite was almost equal while TiO2 nanorods had it slightly lower. The calculated optical thickness values were within the range of optimal value (1.8–4.4) for planar reactors for all the catalysts. The higher catalytic activity is attributed to effective photogenerated charge generation, charge separation, and broad-spectrum absorption of solar light. The Au@CNT@TiO2 nanocomposite exhibits more than two times higher photocatalytic activity as compare to TiO2 nanorods for the degradation of organic dye. Au@CNT@TiO2 nanocomposite shows seven times higher photocurrent density as compare to TiO2 nanorods.