Influence of calcination temperature and solvent of titanium precursor on the photocatalytic activity of N-doped $$\hbox {TiO}_2$$TiO2 nanoparticles in $$\hbox {H}_2$$H2 evolution under visible radiation

In this research, the effect of calcination temperature and solvent of titanium precursor were studied on the photocatalytic activity of N-doped $$\hbox {TiO}_2$$TiO2 nanoparticles used in $$\hbox {H}_2$$H2 evolution under the normal sunlight. A modified sol–gel method was used to improve the surface properties of prepared nanoparticles by using acetic acid and/or ethanol as solvent of titanium precursor. The nanoparticles of $$\hbox {TiO}_2 /\hbox {N}$$TiO2/N were calcined at temperatures of 450, 550, and 650 $$\,^{\circ }\mathrm {C}$$∘C. The techniques of XRD, FT-IR, UV-DRS, TGA, SEM, and EDAX were applied to characterization of the synthesized nanoparticles. A 10% solution of methanol was used for production of $$\hbox {H}_2$$H2 gas in the presence of prepared nanoparticles as photocatalyst, and gas chromatography device was used for measurement of evolved gas. The obtained results showed that the surface reactivity of $$\hbox {TiO}_2 /\hbox {N}$$TiO2/N nanoparticles was increased when the acetic acid was used as solvent of titanium precursor. The more crystallinity of prepared $$\hbox {TiO}_2 /\hbox {N}$$TiO2/N nanoparticles in acetic acid solvent was proposed for this result. Also, the photocatalytic activity of nanoparticles of $$\hbox {TiO}_2 /\hbox {N}$$TiO2/N was decreased with increase in temperature of calcination process. This result was related to the agglomeration of nanoparticles and thus decrease in their surface area with increase in calcination temperature.