Influence of calcination temperature and solvent of titanium precursor on the photocatalytic activity of N-doped ${\text{TiO}}_2$ nanoparticles in ${\text{H}}_2$ 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 ${\text{TiO}}_2$ nanoparticles used in ${\text{H}}_2$ 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 ${\text{TiO}}_2/\text{N}$ were calcined at temperatures of 450, 550, and 650 ${}^{\circ }C$. 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 ${\text{H}}_2$ 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 ${\text{TiO}}_2/\text{N}$ nanoparticles was increased when the acetic acid was used as solvent of titanium precursor. The more crystallinity of prepared ${\text{TiO}}_2/\text{N}$ nanoparticles in acetic acid solvent was proposed for this result. Also, the photocatalytic activity of nanoparticles of ${\text{TiO}}_2/\text{N}$ 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.