Volume 49 Number 3

Effects of calcination heating rate on the photocatalytic activity of Al-doped TiO₂ nanofibers

Watcharapon Nantaouppakan, Nattaya Comsup^*

 
ABSTRACT:     Al-dopedTiO2 nanofibersweresynthesizedusingtheone-stepelectrospinning method. Theas-synthesized nanofiber catalyst was investigated in terms of the effect of calcination heating rate (3 to 10?C/min) at a constant temperature of 500?C. X-ray diffraction analysis revealed that the anatase phase is the dominant phase, and a mixed phase of rutile and anatase was formed when heating rates exceeded 3?C/min. Increasing the heating rate had almost no effect on specific surface area, pore size, and pore volume, while the band gap energy showed a slight decrease from 3.16 to 3.12 eV with increasing heating rate. The calcination heating rate has a distinct effect on the amount of oxygen vacancies and chemisorbed oxygen species of Al-doped TiO2 nanofibers. The increase in heating rate decreased the oxygen vacancies in bulk Al-doped TiO2 nanofibers, while the amount of chemisorbed oxygen increased. The large amount of oxygen vacancies in the lattice of Al-doped TiO2 nanofibers acts as recombination centers for charge carriers, thereby decreasing the efficiency of photocatalysis. Conversely, the large amount of chemisorbed oxygen promotes the formation of active species, resulting in enhanced photocatalytic efficiency. Therefore, Al-doped TiO2 nanofiberscalcined with a heating rate of 10?C/minexhibitedthehighest methylenebluedegradationefficiency of 98% within 120 min under UV light irradiation. It can be concluded that the calcination heating rate is a crucial parameter influencing the formation of oxygen vacancies and active species, which is directly related to the photocatalytic efficiency of Al-doped TiO2 nanofibers.

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* Corresponding author, E-mail: nattaya@pit.ac.th

Received 17 Dec 2024, Accepted 0 0000