Broadband photocatalysis using a Z-scheme heterojunction of Au/NaYF4:Yb,Er/WO3•0.33H2O-W18O49 via a synergetic strateg of upconversion function and plasmonic effect

Employing upconversion hosts (which convert lower-energy light into higher-energy light) and plasmonic Au nanoparticles, this work deals with the synthesis of a novel Au/NaYF4:Yb,Er/WO3 center dot 0.33H(2)O-W18O49 {denoted as A/NYYE/WW} heterojunction via a hydrothermal method followed by a photo-reduction method. Also, A/NYYE/WW exhibited the optimum photocatalytic activity and stronger photocatalytic stability for the degradation of nitrobenzene aqueous solution in comparison with a single WO3 center dot 0.33H(2)O or NYYE/WW component. Based on the results of X-ray diffraction patterns, field emission electron microscopy, X-ray photoelectron spectra, UV-Vis diffuse reflectance spectra, upconversion luminescence spectra, luminescence decay and photoelectrochemical measurements, it could be considered that a Z-scheme heterojunction was generated over A/NYYE/WW, in which a highly efficient Forster resonant energy transfer from NYYE to WO3 center dot 0.33H(2)O-W18O49 was observed and the localized surface plasmon resonance (LSPR) effects of Au NPs and W18O49 could induce the utilization of near infrared light to achieve broadband light absorption. On the other hand, Au NPs also played the role of an electron sink for enhanced charge carrier separation and utilization. Thus, the heterojunction showed the synergetic effects of both upconversion and LSPR features, which could broaden the absorption spectrum to the near infrared region and give rise to a higher yield. It provides a pathway to develop broadband absorption materials in photocatalytic systems.