Anatase TiO₂ has evolved to be one of the most attractive materials for gas sensing due to its strong oxidation activity and excellent sensing properties. In this study, we prepared a Pt and bamboo charcoal co-modified nano-TiO₂ using one-pot hydrothermal process and applied it for detection of formaldehyde. The successful incorporation of precious metal Pt and bamboo charcoal onto TiO₂ was confirmed by SEM, TEM, EDS, XRD, and XPS. These modifiers significantly improved the response of TiO₂ to formaldehyde, e.g., the response signal increased by 4 times, while the response time decreased from 91.05 to 67.76 s. The sample with 0.5@Pt and 0.5@C bamboo charcoal performed the best. Our work showed the potential of using biomass-derived carbon to improve the detection of formaldehyde.

For electrical and sensing characterizations, a small amount of Pt and bamboo charcoal co-modified TiO₂ obtained by grinding was mixed with distilled water and stirred into a sticky shape, then apply to the interdigitated electrode and place in an indoor environment to dry naturally. After drying, the electrode was placed in a tube furnace and sintered under N₂ protection at 250 °C for 1 h. After that, the Pt/TiO₂/C sensor electrode was obtained by waiting for the electrode to cool to room temperature. The prepared electrode was placed in formaldehyde gas environment for gas-sensitive performance test, and the sensing performance of the material was reflected by response strength A: A = (I_a - I₀)/I₀

Where I₀ is the current of the material in the air environment, and Ia is the current of the material in the formaldehyde environment.

A controlled experimental study was conducted to investigate the impact of Pt and bamboo charcoal addition on the sensing performance of Pt/TiO₂/C. Three types of materials were prepared using the hydrothermal method with the same concentration ratio of TiO₂, Pt/TiO₂, and bamboo charcoal-modified TiO₂ (TiO₂/C). The materials were then fabricated into electrodes, and their sensing performance was compared with that of Pt/TiO₂/C.

To determine the optimal composite ratio, the quantity of Pt added to the Pt/TiO₂/C with a 10% Pt modified (the molar ratio of Pt and TiO₂ is 0.1:1) was adjusted. Subsequently, the sensing performance of electrodes fabricated from materials with different Pt modified, including 2.5% Pt (0.25@Pt, 0.25 times the original amount), 5.0% Pt (0.5@Pt), 20% Pt (2.0@Pt), and the original 10% Pt modified (1.0@Pt), was compared to determine the optimal composite ratio. After selecting the better material, the composite ratio of 0.1 g bamboo charcoal in Pt/TiO₂/C was varied. The sensing performance of electrodes fabricated from materials with different bamboo charcoal added, including 0.01 g bamboo charcoal (0.1@C, 0.1 times the original amount), 0.05 g bamboo charcoal (0.5@C), 0.2 g bamboo charcoal (2.0@C), and the original 0.1 g bamboo charcoal (1.0@C), was then compared to determine the optimal composite ratio.