Graphene Oxide (GO)/α-Bi2O3 Versatile Multifunctional Composites for Enhanced Visible Light Photocatalysis, Chemical Catalysis and Solar Energy Conversion

The growing challenges of environmental purification by solar photocatalysis, precious metal free catalysis and photocurrent generation in photovoltaic cells are receiving the utmost global attention. Here we demonstrate the one-pot green chemical synthesis of a new stable heterostructured, eco-friendly, multifunctional micro-composite consisting of α-Bi2O3 micro-needles intercalated with anchored graphene oxide (GO) micro-sheets (1.0 wt%) for the above mentioned applications in a large economical scale. The bare α-Bi2O3 micro-needles display twice as better photocatalytic activities than commercial TiO2 (Degussa-P25) while the GO hybridized composite exhibit ~4-6 times enhanced photocatalytic activities than neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes (crystal violet and rhodamine 6G) under visible light irradiation (300 W tungsten lamp). The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability and efficient electron-hole pair separation in Bi2O3 by individual adjoining GO sheets. Introduction of Ag nanoparticles (2.0 wt%) further enhances the photocatalytic performance of the composite over 8 folds due to a plasmon-induced electron-transfer process from Ag nanoparticles via GO sheets into the conduction band of Bi2O3. The new composites are also catalytically active. They catalyze the reduction of 4-nitrophenol to 4-aminophenol in presence of borohydride ions. Photoanodes assembled from GO/αBi2O3 and Ag/GO/α-Bi2O3 composites display an improved photocurrent response (power conversion efficiency ~ 20% higher) over those prepared without GO in dye-sensitized solar cells (DSSCs).