Ga-Doped 3D Ordered Porous SnO₂ for Enhanced Formaldehyde Sensing Performance

Abstract

Pure and Ga-doped 3D ordered porous SnO2 (3DOPS) nanomaterials were synthesized by a simple template method, and SnO2 nanoparticles (NPs) were prepared by an annealing process. The presence of Ga in 3DOPS and the structure of 3DOPS were determined by X-ray powder diffraction (XRD), energy-dispersive spectroscopy (EDS), X-ray photoelectric spectroscopy (XPS), and scanning electron microscopy (SEM). The surface areas of the porous structure were measured by the BET method using a middle-high pressure physical gas adsorption instrument. Due to the porous structure and dopant effects on the SnO2 nanomaterials, 3 at % Ga-doped 3DOPS has the largest specific surface area (61.58 m2/g) compared with pure particle tin dioxide (38.60 m2/g). The 3 at % Ga-doped 3DOPS-based sensor exhibits a lower detection limit (2/0.1 ppm) and improved sensitivity (55/50 ppm) to formaldehyde (HCHO) at a low temperature (210 °C), and the response is 6.5 times higher than that of the pure SnO2 NP-based sensor (8.5/50 ppm). However, the response of pure 3DOPS (18/50 ppm) is only twice as high as that of the pure SnO2 NP-based sensor. In addition, the 3.0 at % Ga-doped level of the SnO2 sensor showed a fast response time (2 s) and excellent selectivity. The high sensitivity of SnO2 can be explained by the increase in the specific surface area and porosity brought by the 3D ordered porous structure, and the modified suface structure by precious metals.

Pt Nanoparticle-Modified Sn2O3 Nanoflowers with Fast Response for the Detection of Formaldehyde

“…At 0 s, formaldehyde gas was injected, and the tests were carried out. For pure Sn 2 O 3 , spectra were recorded every 60 s and formaldehyde injection was quitted at 120 s. For Pt-Sn 2 O 3 , spectra were recorded every 30 s and formaldehyde injection was quitted at 60 s. The peaks were observed in the range of 1540–1600 cm –1 ascribed to formaldehyde, ,, indicating that gas molecules were first adsorbed onto the sensor surface upon formaldehyde injection (Figure a,b). Then, formaldehyde reacted with the surface oxygen species to generate formic acid, as confirmed by the peak at 1685–1700 cm –1 . , Finally, formic acid further reacted with oxygen species and was oxidized to CO 2 (2356–2360 cm –1 ) and H 2 O (3630–3735 cm –1 ). , By comparison of the in situ FTIR spectra of pure Sn 2 O 3 and Pt-Sn 2 O 3 , it can be seen from the graph that the peaks of formaldehyde and formic acid on the surface of Pt-loaded Sn 2 O 3 were much smaller than those on pure Sn 2 O 3 after formaldehyde introduction.…”

“…At 0 s, formaldehyde gas was injected, and the tests were carried out. For pure Sn 2 O 3 , spectra were recorded every 60 s and formaldehyde injection was quitted at 120 s. For Pt-Sn 2 O 3 , spectra were recorded every 30 s and formaldehyde injection was quitted at 60 s. The peaks were observed in the range of 1540−1600 cm −1 ascribed to formaldehyde, 28,61,62 indicating that gas molecules were first adsorbed onto the sensor surface upon formaldehyde injection (Figure 8a,b). Then, formaldehyde reacted with the surface oxygen species to generate formic acid, as confirmed by the peak at 1685−1700 cm −1 .…”

“…Additionally, SnO 2 nanomaterials also demonstrate excellent application prospects in the detection of formaldehyde gas. Sun et al utilized a template method to synthesize Ga-doped 3D ordered mesoporous SnO 2 nanomaterials, significantly enhancing the response and selectivity for formaldehyde gas detection, and Meng et al synthesized NiO–SnO 2 heterojunction nanoflowers using a one-step hydrothermal method, which significantly reduced the operating temperature for formaldehyde detection . Among them, other valence oxides of tin have also been gradually applied in the study of gas sensing, such as Sn 3 O 4 and Sn 2 O 3 .…”

Insight into Copper Doping Ratio on Optoelectronics Performance of Two-Dimensional Cu-Doped SnO2 Nanosheets: an Experiment and DFT Study

“…Medhi et al 38 successfully synthesized Sb,Zn-doped SnO 2 nanoparticles, which effectively regulated the band gap of SnO 2 nanoparticles and expanded its appropriate application in the field of optoelectronics. Sun et al 39 synthesized 3D Ga-doped SnO 2 nanomaterials. The increased surface area and porosity, as well as gallium doping, greatly improve the sensitivity of SnO 2 to formaldehyde detection.…”

Insights into the solvothermal reaction for synthesizing tin(iv) oxide porous spheres

“…10,11 In addition, two and three dimensional reticulate porous SnO 2 and hollow SnO 2 spheres have been synthesized via hard template methods using polystyrene or carbon spheres as sacricial templates. [13][14][15][16] Although this technology provides materials with a high degree of porosity and very uniform structures based on using monodisperse particles as templates, removal of the sacricial templates is labor-intensive and also results in a substantial waste stream. Solution methods are advantageous when preparing SnO 2 composites, because precursor mixtures of Sn source materials and different metal sources can be readily used as solutions to prepare SnO 2 composites.…”