One-step synthesis of metallic Bi deposited Bi2WO6 nanoclusters for enhanced photocatalytic performance: An experimental and DFT study

Non-noble metallic Bi/Bi2WO6 nanocomposites were synthesized by one-step semi-solvothermal method with water - N-N Dimethylformamide (DMF) under mild conditions. The DMF solvent not only prevents the formation of impurities [Bi6O6(OH)3(NO3)3·1.5H2O] from Bi(NO3)3·5H2O hydrolysis, but also in situ reduces Bi3+ ions to metallic Bi. The DMF percentage ranges from 0 to 100%, and the Bi/Bi2WO6 nanocomposites prepared in a 50% DMF precursor (50-BWO) solution were the most effective in the degradation of rhodamine B (RhB) under simulated sunlight irradiation. The RhB degradation efficiency was about 2.98 and 71.8 times higher than those of pristine Bi2WO6 and Bi microspheres, respectively. Then, the photocatalytic mechanisms of Bi/Bi2WO6 were proposed based on DFT calculations and experimental results. The enhanced photocatalytic activity of Bi/Bi2WO6 results mainly from two factors: the surface plasmonic resonance (SPR) of metallic Bi (which enhances light absorption) and the formation of Ohmic junction between Bi microspheres and Bi2WO6 nanosheets. The ohmic junction facilitates the effective separation of photogenerated carriers, enhancing efficiency. Additionally, the ·O2– and h+ radicals are the main active species in the degradation of RhB. Last, the durability and stability of Bi/Bi2WO6 were verified by cyclic experiments.