Abstract: The sol-gel preparation of nano-TiO₂ and the evaluation of its photocatalytic activity constitute a representative comprehensive experiment for undergraduate students majoring in chemistry, materials science, and related fields. In the conventional protocol, gel-derived TiO₂ precursors are thermally treated in a high-temperature furnace at multiple temperatures over extended durations. This approach suffers from slow heating rates, prolonged equipment occupancy, high energy consumption, and logistical challenges in organizing large laboratory classes. Moreover, under the current risk-based management framework for university laboratories, the prolonged operation of high-temperature equipment intensifies the burden of onsite supervision, routine inspection, and process risk control. To address these issues, microwave hybrid heating was introduced into the thermal treatment stage of TiO₂ precursors, employing graphite powder as a microwave susceptor to achieve rapid crystallization in a domestic microwave oven. The resulting samples were compared with those calcined using a conventional high-temperature furnace. The results showed that microwave hybrid heating produced anatase-phase TiO₂ within a very short time, with crystallographic characteristics comparable to those of samples prepared using a conventional high-temperature furnace. After 10 min of microwave treatment, distinct rutile-phase features emerged, indicating a phase-transition trend similar to that observed for samples treated at higher temperatures in a conventional furnace. In the photocatalytic degradation of methyl orange, the sample obtained by short-duration microwave treatment exhibited a degradation efficiency comparable to that of the conventionally heat-treated sample. The improved experiment markedly shortens the thermal treatment time, alleviates the management burden and energy consumption associated with prolonged high-temperature operation, and integrates the relationship among energy input mode, crystallization behavior, and photocatalytic performance into the teaching process. This experiment features safety, greenness, a short cycle, low cost, and strong inquiry orientation, offering a valuable reference for the enhancement of undergraduate experiments involving nanomaterial preparation.

Key words: Improvement of teaching experiments, Educational value, Microwave-assisted hybrid heating, Green and safe chemistry, Titania (TiO₂), Laboratory safety management