Mesoporous Pt/TiO2-xNx nanoparticles with less than 10 nm and high specific surface area as visible light hydrogen evolution photocatalysts

Mesoporous TiO2-xNx nanoparticles were synthesized by selective dissolving of Si in N-doped Ti-Si binary oxides, which were nitridized at 900 A degrees C in a flow of ammonia gas, and the mesoporous TiO2-xNx photocatalysts were then modified by depositing Pt through a microwave polyol method. The samples were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), N-2 adsorption-desorption, UV-vis spectroscopy and X-ray photoemission spectroscopy (XPS). The results indicated that the addition of SiO2 remarkably changed the phase composition, BET-specific surface area and the photocatalytic H-2 production activity of TiO2-xNx nanoparticles. The incorporation of Si in Ti-Si binary oxides can suppress phase transformation of TiO2 from anatase to rutile and inhibit the TiO2 crystallite growth up to 900 A degrees C. The BET surface area of the mesoporous TiO2-xNx nanoparticle was > 138 m(2) g(-1) while with a crystallite size < 10 nm, and the sample had a good visible light response. Photocatalytic hydrogen production results showed the N-doped Pt/TiO2 derived from Si: Ti = 1:1 of Ti-Si binary oxides exhibited the highest H-2 evolution rate as high as 15.2 mu mol g(-1) h(-1) under visible light irradiation, which is almost 10 times larger than commercial TiO2 nanoparticles P25. In addition, the co-catalyst optimized amount of Pt required for optimal photocatalytic H-2 production activity was 2.0 wt% [GRAPHICS] Mesoporous TiO2-xNx nanoparticles were synthesized by selective dissolving of Si in N-doped Ti-Si binary oxides. The grain size of the mesoporous TiO2-xNx with high BET surface area is < 10 nm after calcined at 900 A degrees C. Mesoporous Pt/TiO2-xNx exhibited H-2 evolution rate as high as 15.2 mu mol g(-1) h(-1), which is almost 10 times larger than P25. The co-catalyst optimized amount of Pt required for optimal photocatalytic H-2 production activity was 2.0 wt%.