Construction of metal/WO2.72/rGO ternary nanocomposites with optimized adsorption, photocatalytic and photoelectrochemical properties

In this work, metal/WO2.72/rGO ternary nanocomposites were constructed by a two-step in situ loading process. The binary WO2.72/rGO nanocomposite was first prepared by in situ growth of ultrathin WO2.72 nanowires on rGO nanosheets via a solvothermal reaction, and the plasmonic metal (Ag and Au) nanoparticles were subsequently loaded on the WO2.72/rGO nanocomposite by an in situ redox. For comparison, a series of nanomaterials including the WO2.72 nanowires, WO2.72/rGO, Ag/WD2.72, Au/WO2.72, Ag/WO2.32/rGO, and Au/WO02.72/rGO, were prepared and characterized in detail. These WO2.72-containing materials showed very high adsorption capacities to the cationic dye of methylene blue (MB) because of the negatively charged surface of WO2.72 nanowires. For the photocatalytic degradation of MB, each of the three components specifically contributes to the performance of the ternary nanocomposite photocatalysts. The WO2.72 nanowires provide high adsorption of the target molecules. The metal nanoparticles extend the visible light response range due to their SPR effect and increase the lifetime of the photo generated electron-hole pairs as well. The rGO nanosheets further increase the adsorption and offer a rapid transferring path for the photogenerated electrons, achieving an efficient charge separation. The ternary nanocomposites showed the highest photocatalytic activity towards degradation of MB and the highest photocurrent when served as photoelectrode materials. The electrochemical impedance spectra (EIS) Nyquist plots also confirmed the highest charge transfer efficiency of the metal/WO2,72/rGO ternary nanocomposites. Therefore, the integration of the three components could achieve collective effect to greatly increase the efficiency of visible-light conversion. (C) 2016 Elsevier B.V. All rights reserved.