Catalysis Today, Vol.341, 49-58, 2020
An alternative method for the synthesis of functional Au/WO3 materials and their use in the photocatalytic production of hydrogen
Deposition-precipitation has demonstrated to efficiently support tiny and well dispersed Au nanoparticles on the surface of various semiconductors, although its efficiency is low when the isoelectric point (IEP) of the support falls below 3.0. This work proposes an alternative method for the deposition of Au metallic nanoparticles on WO3 (IEP similar to 0.5), which is based on the cationic adsorption process. WO3 and [Au(en)(2)]Cl-3 complex were synthesized by known methods, and the adsorption efficiency of the complex on the WO3 surface was tested using different pH values (1, 4, 7 and 10) and reaction times (2, 12 and 16 h). Complete deposition of Au on WO3 was achieved upon 16 h and pH = 10. Using the optimal reaction conditions, several Au loadings were successfully deposited on WO3, namely 0.1, 0.5, 1.0 and 3.0 wt.%, giving as a result highly dispersed 3-4 nm Au nanoparticles on the WO3 surface. The functionality of the synthesized materials was evaluated via the photocatalytic production of hydrogen. The highest performance was obtained using the (0.5 wt.%) Au/WO3 material. Electrochemical characterization showed how Au nanoparticles modified the Fermi level toward more negative values, increasing the photocatalytic reduction of water molecules at the optimal Au loading.