Highly sensitive triethylamine gas sensor by Pt-loaded p-n heterojunction Co3O4/WO3.

Triethylamine (TEA) exists widely in production and life and is extremely volatile, which seriously endangers human health. It is required to develop high-performance TEA sensors to protect human health. We fabricated Pt-Co3O4/WO3based on our previous work, and the performance was tested against volatile organic compounds. Compared with the previous work, its operating temperature was greatly reduced from 240 °C to 180 °C. The response value of Pt-Co3O4/WO3was increased from 1101 to 1532 for 10 ppm TEA with good selectivity. These results show a significant step toward practical use of the Pt-Co3O4/WO3sensor.

Ultrasensitive Formaldehyde Sensor Based on SnO2 with Rich Adsorbed Oxygen Derived from a Metal Organic Framework.

SnO2 has been a commonly researched gas-sensing material due to its low cost, good performance, and good stability. However, gas sensors based on pure SnO2 usually show a low response or high working temperature. In this work, laminar SnO2 was obtained by using a Sn-based metal organic framework(Sn-MOF)@SnO2 as a precursor. Sn-MOF@SnO2 is prepared at low temperatures using water and dimethylformamide as a solvent, which is simple, low cost, and easily reproducible. After sintering, Sn-MOF@SnO2 is derived to SnO2 with rich adsorbed oxygen, large specific surface area, and unique nanoparticle piled pores, thus showing excellent gas-sensing properties. The prepared SnO2 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 SnO2 can effectively increase the coadsorption capacity of O2 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.

Silver nanoparticles embedded 2D g-C3N4nanosheets toward excellent photocatalytic hydrogen evolution under visible light.

Photocatalytic water splitting is considered to be a feasible method to replace traditional energy. However, most of the catalysts have unsatisfactory performance. In this work, we used a hydrothermal process to grow Ag nanoparticlesin situon g-C3N4nanosheets, and then a high performance catalyst (Ag-g-C3N4) under visible light was obtained. The Ag nanoparticles obtained by this process are amorphous and exhibit excellent catalytic activity. At the same time, the local plasmon resonance effect of Ag can effectively enhance the absorption intensity of visible light by the catalyst. The hydrogen production rate promote to 1035µmol g-1h-1after loaded 0.6 wt% of Ag under the visible light, which was 313 times higher than that of pure g-C3N4(3.3µmol g-1h-1). This hydrogen production rate is higher than most previously reported catalysts which loaded with Ag or Pt. The excellent activity of Ag-g-C3N4is benefited from the Ag nanoparticles and special interaction in each other. Through various analysis and characterization methods, it is shown that the synergy between Ag and g-C3N4can effectively promote the separation of carriers and the transfer of electrons. Our work proves that Ag-g-C3N4is a promising catalyst to make full use of solar energy.

Pt Single Atom-Induced Activation Energy and Adsorption Enhancement for an Ultrasensitive ppb-Level Methanol Gas Sensor.

As an important organic chemical raw material, methanol is used in various industries but is harmful to human health. Developing an effective and accurate detection device for methanol is an urgent need. Herein, we demonstrate a novel gas-sensing material with a Pt single atom supported on a porous Ag-LaFeO3@ZnO core-shell sphere (Ag-LaFeO3@ZnO-Pt) with a high specific surface area (192.08 m2·g-1). Based on this, the surface activity of the Ag-LaFeO3@ZnO-Pt gas sensor is enhanced obviously, which improved the working temperature and detection limit for methanol gas. Consequently, this sensor possesses an ultrahigh sensitivity of 453.02 for 5 ppm methanol gas at a working temperature of 86 °C and maintains a high sensitivity of 21.25 even at a concentration as low as 62 ppb. The sensitivity of Ag-LaFeO3@ZnO-Pt to methanol gas is increased by 6.69 times compared with the Ag-LaFeO3@ZnO core-shell sphere (Ag-LaFeO3@ZnO). Additionally, the minimum detection limit is found to be 3.27 ppb. Detailed theoretical calculations revealed that the unoccupied 5d state of Pt single atoms increases the adsorption and activation energy of methanol and oxygen, which facilities methanol gas-sensing performance. This work will provide a novel strategy to design high-performance gas-sensing materials.

Ultrasensitive ppb-level trimethylamine gas sensor based on p-n heterojunction of Co3O4/WO3.

Trace poisonous and harmful gases in the air have been harming and affecting people's health for a long time. At present, effective and accurate detection of ppb-level harmful gas is still a bottleneck to be overcome. Herein, we report a ppb-level triethylamine (TEA) gas sensor based on p-n heterojunction of Co3O4/WO3, which is prepared with ZIF-67 as the precursor and provides Co3O4deposited tungsten oxide flower-like structure. Due to the introduction of Co3O4and the 3D flower-like structure of WO3, the Co3O4/WO3-2 gas sensor shows excellent gas sensing performance (1101 for 10 ppm at 240 °C), superb selectivity, good long-term stability and linear response for TEA concentration. Moreover, the experimental results indicate that the Co3O4/WO3-2 gas sensor also possesses a good response to 50 ppb TEA, in fact, the theoretical limit of detection is 0.6 ppb. Co3O4not only improves the efficiency of electron separation/transport, but also accelerates the oxidation rate of TEA. This method of synthesizing p-n heterojunction with ZIF as the precursor provides a new idea and method for the preparation of low detection limit gas sensors.

Platinum-Supported Cerium-Doped Indium Oxide for Highly Sensitive Triethylamine Gas Sensing with Good Antihumidity.

Triethylamine is extremely harmful to human health, and chronic inhalation can lead to respiratory and hematological diseases and eye lesions. Hence, it is essential to develop a triethylamine gas-sensing technology with high response, selectivity, and stability for use in healthcare and environmental monitoring. In this work, a simple and low-cost sensor based on the Pt- and Ce-modified In2O3 hollow structure to selectively detect triethylamine is developed. The experimental results reveal that the sensor based on 1% Pt/Ce12In exhibits excellent triethylamine-sensing performance, including its insusceptibility to water, reduced operating temperature, enhanced response, and superior long-term stability. This work suggests that the enhancement of sensing performance toward triethylamine can be attributed to the high relative contents of OV and OC, large specific surface area, catalytic effect, the electronic sensitization of Pt, and the reversible redox cycle properties of Ce. This sensor represents a unique and highly sensitive means to detect triethylamine, which shows great promise for potential applications in food safety inspection and environmental monitoring.