UV-Enhanced Formaldehyde Sensor Using Hollow In₂O₃@TiO₂ Double-Layer Nanospheres at Room Temperature

Abstract

Hollow In 2 O 3 @TiO 2 double-layer nanospheres were prepared via a facile water bath method using the sacrifice template of carbon nanospheres. It is shown that the size of the In 2 O 3 /TiO 2 nanocomposites is 150−250 nm, the thickness of the In 2 O 3 shell is about 10 nm, and the thickness of the TiO 2 shell is about 15 nm. The sensing performances of the synthesized In 2 O 3 /TiO 2 nanocomposites-based chemiresistive-type sensor to formaldehyde (HCHO) gas under UV light activation at room temperature have been studied. Compared to the pure In 2 O 3 -and pure TiO 2based sensors, the In 2 O 3 /TiO 2 nanocomposite sensor exhibits much better sensing performances to formaldehyde. The response of the In 2 O 3 /TiO 2 nanocomposite-based sensor to 1 ppm formaldehyde is about 3.8, and the response time and recovery time are 28 and 50 s, respectively. The detectable formaldehyde concentration can reach as low as 0.06 ppm. The role of the formed In 2 O 3 /TiO 2 heterojunctions and the involved chemical reactions activated by UV light have been investigated by AC impedance spectroscopy and the in situ diffuse reflectance Fourier transform infrared spectroscopy. The improvement of the sensing properties of In 2 O 3 / TiO 2 nanocomposites could be attributed to the nanoheterojunctions between the two components and the "combined photocatalytic effects" of UV-light-emitting diode irradiation. Density functional theory calculations demonstrated that introducing heterojunctions could improve the adsorption energy and charge transfer between formaldehyde and sensing materials.

Cu–Pt/CrN Fuel Cell Gas Sensor Achieves ppb-Level H2S Detection at Room Temperature

“…This enhances orbital hybridization, further reinforces the bonding, and enhances the stability of the adsorbed species. 30 These findings highlight the crucial role played by covalent bonding and augmented orbital hybridization in promoting the chemisorption mechanism between H 2 S and Cu−Pt/CrN. H 2 S Gas-Sensing Mechanism.…”

Solvent-Free Synthesis of Cu/In Dual-Single-Atom-Doped TiO2 for Photocatalytic Reduction of Cr (VI) with High Efficiency

“…42 The typical binding energies of In 3d 3/2 and In 3d 5/2 are located at 452.3 eV and 444.7, respectively (Figure 4e). 43 The XPS patterns of Cu and In reveal that Cu and In atoms exist as Cu 2+ and In 3+ in the TiO 2 , and the binding energies of Ti 2p and O 1s change after Cu and In doping, illustrating that the Cu and In atoms are on the Ti vacancy sites to be fixed in the lattice of titanium dioxide, not loaded as metal nanoparticles or physical adsorption on the surface of TiO 2 .…”

An innovative Z-type Sb2S3/In2S3/TiO2 heterostructure: superior performance in the photocatalytic removal of levofloxacin and mechanistic insight

“…14,15 However, the catalytic performance of pure TiO 2 is affected by the wide band gap (3.2 eV) and high photogenerated carrier recombination rate. [16][17][18] In order to improve its photocatalytic activity and stability in practical applications, many methods have been proposed, such as optimising the structure of TiO 2 and constructing heterostructures. [19][20][21] Since the photocatalytic degradation of antibiotics occurs at the semiconductor-water interface, vertically aligned semiconductor nanoarrays (e.g., nanorods or nanosheets) provide a large number of active sites, reduce carrier diffusion distances and enable multiple light reections between arrays, which can enhance the photocatalytic degradation of LEVs by improving the photo-generated charge separation efficiency of photocatalyst.…”

“…14,15 However, the catalytic performance of pure TiO 2 is affected by the wide band gap (3.2 eV) and high photogenerated carrier recombination rate. 16–18 In order to improve its photocatalytic activity and stability in practical applications, many methods have been proposed, such as optimising the structure of TiO 2 and constructing heterostructures. 19–21…”