No abstract

SnO 2 has been a commonly researched gas-sensing material due to its low cost, good performance, and good stability. However, gas sensors based on pure SnO 2 usually show a low response or high working temperature. In this work, laminar SnO 2 was obtained by using a Sn-based metal organic framework(Sn-MOF)@SnO 2 as a precursor. Sn-MOF@SnO 2 is prepared at low temperatures using water and dimethylformamide as a solvent, which is simple, low cost, and easily reproducible. After sintering, Sn-MOF@SnO 2 is derived to SnO 2 with rich adsorbed oxygen, large specific surface area, and unique nanoparticle piled pores, thus showing excellent gas-sensing properties. The prepared SnO 2 has an ultrahigh response value of 10,000 to 10 ppm formaldehyde at an optimal working temperature of 120 °C, a fast response/ recovery time of 33 s/142 s, and an actual detection limit of lower than 10 ppb as well as high selectivity and high stability. Density functional theory calculations show that the exposed (110) plane of oxygen-rich vacancies in laminar SnO 2 can effectively increase the coadsorption capacity of O 2 and formaldehyde molecules, thereby improving the formaldehyde gas-sensing performance of the material. The present original approach paves the way to design advanced materials with excellent gas-sensing properties as well as broad application prospects in formaldehyde monitoring.

Triethylamine (TEA) significantly harms the human body, so it is important to develop a TEA gas sensor with excellent performance for TEA detection. In this work, a Pd/PdO-In2O3 TEA gas...

Artificially inducing abundant oxygen vacancies in perovskite-structured materials is an effective method to improve sensing activity.

Triethylamine (TEA) is a serious threat to people's health, and it is still a challenge to detect TEA at ppb level near room temperature (RT). Herein, we developed a simple, low-cost, low-temperature, and ultra-sensitive TEA sensor based on Pd-SnO 2 /In 2 O 3 composites. First, SnO 2 nanoparticles were obtained by the pyrolysis of Sn-MOF@SnO 2 precursor (MOF: metal organic framework), and Pd-SnO 2 /In 2 O 3 composites were prepared by further compounding and doping. The results show that the Pd-SnO 2 /In 2 O 3 sensor is highly sensitive to TEA gas at near RT (at 60 °C, the sensor response to 10 ppm TEA is 12,000, the response/recovery (res/rec) time is 51 s/493 s, and at 30 °C, the response value also reaches 1380, the res/rec time is 66 s/610 s), along with good selectivity, stability, and moisture resistance. Even at 10 °C operating temperature and 75% relative humidity (RH) in a low-temperature and high-humidity environment, it still maintains a high sensitivity of over 1000 to 10 ppm TEA, which shows great application potential in TEA detection. The reason for the enhanced performance of the 0.5%Pd-SnO 2 /In 2 O 3 sensor can be attributed to a large number of adsorbed oxygens on the unique structure of the material, the good charge transfer ability of the n-n-type heterojunction between SnO 2 and In 2 O 3 , the chemical sensitization and electronic sensitization of Pd nanoparticles, and the catalytic spillover effect. This work will provide a new approach for preparing sensors with good comprehensive properties, making full use of the advantages of the material structure−activity relationship.

Using n-type and p-type semiconductor materials to construct p–n heterostructures has proven effective for improving gas-sensing properties. In this study, we synthesized the nanocomposites of SnO2 derived from a metal–organic framework (MOF) and LaFeO3 by loading atomic silver on its surface. The response value (R a/R g) of the nanocomposites to 10 ppm formaldehyde reached 498 at 140 °C, but they showed almost no response to 50 ppm interference volatile organic compounds (VOCs), and the response–recovery time was 105 and 27 s, respectively. The crystal structure, heterojunction structure, chemical elements, and sensitive mechanism were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), Brunauer–Emmett–Teller (BET) analysis, and energy-dispersive spectrometry (EDS) elemental mapping. The characterizations revealed that the improvement of gas sensitivity was mainly due to the MOF-driven strategy, p–n heterojunction, and electron sensitization effect of Ag. This work provides a method and idea for preparing composites and shows the potential application value of LaFeO3@SnO2/Ag nanomaterials in formaldehyde gas detection.

Herein, We proposed a strategy of etching the dopant to construct more unsaturated coordination Mo atoms and lattice distortion for enhancing the catalytic activity of Mo2C. It is more effective...

Sensitive and stable triethylamine (TEA) gas sensors are desirable for environmental and human safety. However, the high operating temperature of the metal-oxidebased gas sensors poses a limitation on their wide applications. Herein, we fabricate an exceptional TEA gas sensor based on the core−shell heterostructure comprising crystalline CuO and amorphous In 2 O 3 /ZnO (CuInZnO) via a facile electrodeposition method. Remarkably, the optimum gas sensor (CuInZnO-3) exhibits an outstanding gas response (∼25) toward a 10 ppm TEA at room temperature. Moreover, CuInZnO-3 shows excellent selectivity, linear response, and stability. The superior sensing performance can be mainly ascribed to the unique core−shell nanorod heterostructure with a high specific surface area, allowing the formation of p−n junctions. The amorphous nature of the In 2 O 3 /ZnO shell also enriches the active oxygen on the surface and enhances gas adsorption.