Low-temperature sol–gel synthesis of anatase nanoparticles modified by Au, Pd and Pt and activity of TiO2/Au, Pd, Pt photocatalysts in water splitting

Base catalyzed hydrolysis and condensation of Ti isopropoxide with water at ambient temperature and molar ratio H2O/Ti(i-PrOH)4 varied from 1 to 100 was studied. It was found that molar ratio H2O/Ti(i-PrOH)4 = 100 originated amorphous TiO2-precursor of summary composition TiO1.9(OH)0.2 with a specific surface area of 354 m2/g. Low-temperature crystallization of amorphous TiO2-precursor to nanostructured anatase at 80 °C in a slightly reducing environment of d-glucose was studied. It was found that the low-temperature nucleation and crystallization of anatase was initiated (activated) by combined effects of d-glucose and Au0, Pd0 and Pt0 nanoparticles, generated in situ by slow reduction of Au3+, Pd2+ and Pt4+ ions using d-glucose. Considerable photocatalytic activity of Ti-hydroxide-oxide/Au, Pd, Pt catalysts prepared at low-temperature was associated with high content of nanostructured anatase and low content of Au, Pd and Pt nanoparticles (0.02 wt.%) effectively deposited on the surface of titania particles. The maximum hydrogen evolution rates 3.4 μmol/min g at Ti-hydroxide-oxide/Au, 4.0 μmol/min g at Ti-hydroxide-oxide/Pd and 4.1 μmol/min g at Ti-hydroxide-oxide/Pt were found. The activity of all TiO2/Au, Pd and Pt catalysts increased by calcination at 600 °C from 50 to 100 %.