Flux-assisted synthesis of SnNb2O6 for tuning photocatalytic properties†
A flux-assisted method was used to synthesize SnNb2O6 as a visible-light-responsive metal oxide photocatalyst. The role of flux was investigated in detail using different flux to reactant molar ratios (1 : 1, 3 : 1, 6 : 1, 10 : 1, and 14 : 1) and different reaction temperatures (300, 500, and 600 °C). The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), the Brunauer–Emmett–Teller method (BET), and high resolution scanning transmission electron microscopy (HRTEM). Flux-assisted synthesis led to tin niobate particles of platelet morphology with smooth surfaces. The synthesized crystal showed a 2D anisotropic growth along the (600) plane as the flux ratio increased. The particles synthesized with a high reactant to flux ratio (1 : 10 or higher) exhibited slightly improved photocatalytic activity for hydrogen evolution from an aqueous methanol solution under visible radiation (λ > 420 nm). The photo-deposition of platinum and PbO2 was examined to gain a better understanding of electrons and hole migration pathways in these layered materials. The HR-STEM observation revealed that no preferential deposition of these nanoparticles was observed depending on the surface facets of SnNb2O6.