Tuning reactivity of Bi2MoO6 nanosheets sensors toward NH3 via Ag doping and nanoparticle modification.

Glucose-assisted combustion synthesis of oxygen vacancy enriched α-MoO3 for ethanol sensing

Mesoporous WS2/MoO3 hybrids were synthesized by a facile two-step and additive-free hydrothermal approach and employed for high-performance trace ammonia gas (NH3) detection. Compared with single WS2 and MoO3 counterparts, WS2/MoO3 sensors exhibited an improvement in NH3-sensing performance at room temperature (22 ± 3 °C). Typically, the optimal WS2/MoO3 sensor showed a higher and quicker response of 31.58% within 57 s toward 3 ppm of NH3, which was 17.7- and 57.4-fold larger than that of pure MoO3 (1.78% within 251 s) and WS2 (0.55% within 153 s) ones. Meanwhile, good reversibility, sensitivity, and selectivity, reliable long-term stability, and the lowest detection limit of 9.0 ppb were achieved. These superior properties were probably ascribed to numerous heterojunctions favorable for additional carrier-concentration modulation via the synergetic effect between WS2 and MoO3 components and the large specific surface area beneficial for richer sorption sites and faster molecular transfer at room temperature. Such achievements also imply that the designed WS2/MoO3 heterostructure nanomaterials have the potential in achieving trace NH3 recognition catering for the requirements of high sensitivity and low power consumption in future gas sensors.

Mesoporous WS2/MoO3 Hybrids for High-Performance Trace Ammonia Detection.

High-response n-butanol gas sensor based on ZnO/In2O3 heterostructure

Ammonia is harmful to human health, however, the detection limit of the sensor based on traditional semiconductor gas sensors is high and the speed is slow. Constructing heterostructure is an effective method to improve the performance of sensors. In this article, 1-D MoO3 nanorods and SnO2 nanoparticles are successfully combined to obtain MoO3/SnO2 nanocomposite. The 1-D structure can increase the speed of electron transport, while the nanoparticles on the surface increase the specific surface area, more importantly, the structure maximizes the interface area between the two materials which can transfer electronic more efficiently. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and Barrett–Joyner–Halenda (BJH) are used to analyze the microstructure and elemental composition of MoO3/SnO2. The diameter of MoO3/SnO2 nanocomposite is approximately 200 nm and the distribution is uniform. The response of MoO3/SnO2 nanocomposite to 100-ppm NH3 is 12.7 at 280 °C, and the response/recovery time is 13/2 s. The detection limit for NH3 can reach 10 ppb (response 1.3), which enables rapid detection of NH3 at low concentration. Electron transport requires more energy to overcome the contact barrier between pure SnO2 nanoparticles, which can also lead to electron emission and noise increase. However, the sensitive electrons of MoO3/SnO2 nanocomposite can transmit electrons along the 1-D rod-like structure of MoO3, which undoubtedly accelerates the efficiency of electron transmission. Moreover, n-n heterojunction formed between MoO3 and SnO2 to bend the SnO2 band and show better sensitivity to NH3. Therefore, MoO3/SnO2 nanocomposite shows a low detection limit and a rapid response/recovery speed. Nevertheless, the nanoparticles on the surface of MoO3/SnO2 nanocomposite begin to agglomerate with the increase of SnO2 content, which leads to the decrease of gas-sensitive response. The formation process of MoO3/SnO2 composites is also discussed in this article. The excellent gas sensing results show that MoO3/SnO2 composites are a promising gas sensing material.

MoO 3 /SnO 2 Nanocomposite-Based Gas Sensor for Rapid Detection of Ammonia

MoO3 is favored by scholars for its satisfactory gas-sensitive performance, and has made outstanding achievements in the detection of NH3. In this paper, MoO3 nanorods are loaded with Au to obtain Au@MoO3, in order to further improve the gas sensitivity. By means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and X-ray photoelectron spectra (XPS), it is confirmed that Au nanoparticles are successfully modified on MoO3 nanorods. The Au nanoparticles with the diameter of about 20–40 nm are uniformly dispersed on the surface of the nanorods with the diameter of about 100–200 nm. Gas sensitivity test results show that Au@MoO3 has excellent sensitivity to NH3, and strong anti-interference to other gases, with outstanding selectivity. The response of Au@MoO3 to 100 ppm NH3 at the optimum operating temperature of 370 °C is as high as 882.5, moreover, it can detect NH3 as low as 1 ppm (response 8.6). Compared with pure MoO3 nanorods, the sensitivity is improved and the operating temperature is reduced. The sensitive mechanism of Au@MoO3 is also discussed.

Highly Sensitive and Selective NH 3 Sensor Based on Au Nanoparticle Loaded MoO 3 Nanorods

Leakage of organic gas in an industrial environment can easily cause fire and explosion accidents. Rapid detection of gases type and concentration is the premise for emergency treatment of these situations. Typically, the single semiconductor sensor cannot detect multicomponent gas. Here, a new multicomponent gas detection method was proposed based on the temperature-response relationship of the sensor. This method has low power consumption, low cost, and long-term monitoring, which can guide the future exploration of deployable sensors. First, the parameters were optimized according to cosine distance to reflect the maximum difference in the temperature-response relationship. Then coordinate system transformation was carried out to further magnify the difference between gases. Finally, the multicomponent gas was recognized by using rational Taylor function fitting. As a proof of concept, we measured the type and concentration of toluene and butanone multicomponent gas with a mean error of 6.34% and 4.32%, respectively. We analyzed the gas-sensing response mechanism, the theoretical support of the optimized parameters, and the causes of local errors. As a universal method, binary component gas detection was explored containing toluene, butanone, acetic anhydride, acetone, and diethyl ether.

Multicomponent Gas Detection Method via Dynamic Temperature Modulation Measurements Based on Semiconductor Gas Sensor

Electronic structure analysis of NiO quantum dot-modified jackfruit-shaped ZnO sensors and sensing properties investigation of their highly sensitive and selective for butyl acetate.

Yang Liu

Papers

Highly Sensitive and Selective NH 3 Sensor Based on Au Nanoparticle Loaded MoO 3 Nanorods

Multicomponent Gas Detection Method via Dynamic Temperature Modulation Measurements Based on Semiconductor Gas Sensor

MoO 3 /SnO 2 Nanocomposite-Based Gas Sensor for Rapid Detection of Ammonia

Electronic structure analysis of NiO quantum dot-modified jackfruit-shaped ZnO sensors and sensing properties investigation of their highly sensitive and selective for butyl acetate.

Interference suppression strategies for trace minor component of semiconductor gas sensor based on temperature modulation mode