Photocatalytic hydrogen production using visible-light-responsive Ta3N5 photocatalyst supported on monodisperse spherical SiO2 particulates

Abstract Fine nanoparticles of Ta 3 N 5 (10–20 nm) were synthesized on the surfaces of SiO 2 spheres with a diameter of ∼550 nm. A sol–gel method was used to modify the surface of SiO 2 with Ta 2 O 5 from TaCl 5 dissolved in ethanol in the presence of citric acid and polyethylene glycol. The resulting oxide composites were treated in an NH 3 flow at 1123 K to form core–shell structured Ta 3 N 5 /SiO 2 sub-microspheres. The obtained samples were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDX), transmission electron microscopy (TEM), and photocatalytic activity measurements for H 2 evolution from an aqueous methanol solution. The XRD results demonstrate the expected sequential formation of Ta 2 O 5 layers, followed by Ta 3 N 5 after nitridation on the Ta 2 O 5 /SiO 2 composite. SEM and TEM observations indicate that the obtained Ta 3 N 5 /SiO 2 sub-microspheres have a uniform size distribution with high crystallinity and an obvious core–shell structure. The presence of support maintained the intrinsic photocatalytic activity of Ta 3 N 5 nanoparticles, but it did drastically improve the dispersion of the photocatalysts in the solution. This study proposes the use of an inert support in photocatalytic reactors to improve ease of handling the powder photocatalyst for gas-phase photocatalysis and the suspension of the solution, controlling nature of light harvesting and degree of scattering of the photoreactor.