Due to global industrial growth and increased emissions of particular gases (such as NO2, H2S or VOC), indoor and outdoor air quality monitoring has become a major issue today. These gases in sufficiently high concentrations bring a negative effect to the environment and human healthy.

As a member of the antibiotic family, nitrofurazone (NFZ) is commonly used to treat burned skin, scratches, and wounds. However, it may cause physical or functional defects in the human embryo or fetus. If it is ingested by humans through the food chain, it can also cause cancer. Therefore, it is prohibited from being used in humans and animals worldwide. As people pay more and more attention to environmental pollution and human health, it is necessary to develop a suitable and sensitive platform to detect NFZ in the environment and water bodies.

Recently, researchers have prepared WO3/CuMnO2 nanocomposite for photoelectrochemical detection of nitrofurazone has been applied for photoelectrochemical detection of nitrofurazone (NFZ). The preparation process is as below:

WO3 nanotiles were synthesized by using CTAB assisted hydrothermal method. In this synthesis, about 2 g of Na2WO4 and a certain amount of CTAB were dissolved in 70 ml of DI water and stirred for an hour to homogenize. To this solution, concentrated HNO3 was added carefully by dropwise to adjust the pH to 3. Finally, the solution was transferred into a 100 ml Teflon-Autoclave hydrothermal pot, and the reaction was initiated at 80 °C for 12 h. The obtained product was washed several times with ethanol and water repeatedly. The received light yellowish powder sample was dried at 80 °C over 24 h and was kept into calcination for 4 h at 450 °C.

The CuMnO2 nanoparticles were prepared by a simple and facile ultrasound-assisted hydrothermal method. For the synthesis, about 360 mg of Cu(NO3)2·3H2O and 380 mg of Mn(NO3)2·3H2O were added in 80 ml of DI water and sonicated for an hour. Then the solution was transferred into 100 ml Teflon autoclave and sealed tightly. Then the hydrothermal reaction was carried out at 120 °C for 24 h. The obtained reddish-brown precipitate was washed with alcohol and DI water several times and oven-dried at 80 °C for 12 h.

The CuMnO2 decorated WO3 nanotiles were prepared by following a simple impregnation method. For the synthesis, 100 mg of WO3 was dispersed in 15 ml of ethyl alcohol by sonication for 30 min. Then aliquot of CuMnO2 particles was added next to the dispersion and again subjected to sonication for 30 min. The resulting dispersion was heated on a hot plate at 120 °C until the complete evaporation of the alcohol medium. The final product was oven-dried at 75 °C for further applications. During the preparation, X weight percentages of CuMnO2 (X = 5, 10, 15, 20, 25) were added to the WO3 dispersion and the obtained composites were named accordingly as WO3/CuMnO2-5, WO3/CuMnO2-10, WO3/CuMnO2-15, WO3/CuMnO2-20, and WO3/CuMnO2-25 respectively.

In conclusion, WO3/CuMnO2 nanocomposite for photoelectrochemical detection of nitrofurazone has been successfully prepared and has been applied for photoelectrochemical detection of nitrofurazone (NFZ). The photoelectrochemical NFZ sensing performance of WO3/CuMnO2 nanocomposite was 1.9 times higher than that of as-synthesized pure WO3 nanotiles. The resulting higher photoelectrochemical performance of the nanocomposite is due to more visible light absorption ability and synergy from p-n heterojunction formation. The designed WO3/CuMnO2 nanocomposite sensor gives satisfactory photocurrent signals for the detection of NFZ in the range of 0.015–32 μM with the detection limit (LOD) of 1.19 nM. The practical applicability of the nanocomposite sensor was monitored in pork liver and tap water samples.

As a new material, ultra-fine particles are used more and more widely. Ultra-fine tungsten powder or tungsten carbide powder as the raw material for the production of ultra-fine grained cemented carbide has also received great attention from metallurgists. A lot of research has been done on the production of ultrafine tungsten powder or tungsten carbide powder at home and abroad. 

Tungsten alloys have three kinds of types, tungsten-molybdenum alloys, niobium-tungsten alloys and hard alloys according to different added elements. Tungsten-Molybdenum Alloy is an alloy containing molybdenum and tungsten, which includes two series of molybdenum-tungsten alloy with molybdenum as the main additive element and tungsten-molybdenum alloy with tungsten as the main additive element. The two alloys can be formed in any ratio and are completely solid solution alloys at many temperatures.

The nominal compositions of commonly used Molybdenum-Tungsten Alloy are Mo-30W, Mo-50W and Mo-85W.The Mo-W alloy can be regarded as a transition alloy between Mo and W. Therefore, the alloy can be applied in a wide temperature range between molybdenum and tungsten.

Tungsten trioxide (WO3) powder has been used to produce filaments and tungsten carbide. As more characteristics are discovered, WO3 powder has been widely used in electrochromic displays, semiconductor gas sensors, photocatalysts and other devices due to its excellent electrochromic, gastrochromic, thermochromic and photochromic properties. WO3 powders with nanostructures are believed to have the enhanced properties because of their larger surface area and unique physical properties.

Tungsten trioxide (WO3) is an N-type semiconductor material that has been widely studied for use in sensors, electrochromism, photocatalysts, and energy storage devices. A simple and low-cost microwave-assisted method have been adopted to prepare the composite.

Gas sensing at room temperature has attracted a lot of research interest, especially the combination of MOX, CNT and graphene, but it usually has the problems of slow response time, poor baseline stability, and high humidity dependence.

High-performance gas sensors are receiving more and more attention due to their wide application in pollutant detection, medical diagnosis, chemical monitoring, food processing and other fields. Tungsten oxide (WOx) has received considerable attention as a promising sensing material due to its high sensitivity and stability, specifically towards hydrogen sulfide (H2S) gas. Various WO3 nanostructures such as nanoparticles, nanowhisker, nanorods, and nanowires have shown enhanced sensing properties towards different gases.

Cemented carbide or tungsten carbide (W2C) is widely used in cutting tools, drilling tools and wear-resistant tools due to its excellent tensile strength, fracture toughness, thermal shock resistance and hardness. By reducing the grain size of WC or adding appropriate reinforcing materials, the mechanical properties of cemented carbide can be greatly improved. The grain size of WC can be suppressed by adding a grain inhibitor or using low-temperature rapid sintering.