Photo-electrochemical hydrogen generation from water using solar energy. Materials-related aspects

Nanocomposites, a high performance material exhibit unusual property combinations and unique design possibilities. With an estimated annual growth rate of about 25% and fastest demand to be in engineering plastics and elastomers, their potential is so striking that they are useful in several areas ranging from packaging to biomedical applications. In this unified overview the three types of matrix nanocomposites are presented underlining the need for these materials, their processing methods and some recent results on structure, properties and potential applications, perspectives including need for such materials in future space mission and other interesting applications together with market and safety aspects. Possible uses of natural materials such as clay based minerals, chrysotile and lignocellulosic fibers are highlighted. Being environmentally friendly, applications of nanocomposites offer new technology and business opportunities for several sectors of the aerospace, automotive, electronics and biotechnology industries.

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Nanocomposites: synthesis, structure, properties and new application opportunities

Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatology and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and laboratory applications are reviewed and presented in this article. The survey frequently concentrates on the RH sensors based upon their organic and inorganic functional materials, e.g., porous ceramics (semiconductors), polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and production technologies. Furthermore, performance characteristics of the different humidity sensors such as electrical and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the preparation of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types.

/pdf/humidity-sensors-principle-mechanism-and-fabrication-q8mq7scozc.pdf

Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review

In this work, a microwave approach is developed to rapidly synthesize ultralong zinc pyrovanadate (Zn3 V2 O7 (OH)2 ·2H2 O, ZVO) nanowires with a porous crystal framework. It is shown that our synthesis strategy can easily be extended to fabricate other metal pyrovanadate compounds. The zinc pyrovanadate nanowires show significantly improved electrochemical performance when used as intercalation cathode for aqueous zinc-ion battery. Specifically, the ZVO cathode delivers high capacities of 213 and 76 mA h g-1 at current densities of 50 and 3000 mA g-1 , respectively. Furthermore, the Zn//ZVO cells show good cycling stability up to 300 cycles. The estimated energy density of this Zn cell is ≈214Wh kg-1 , which is much higher than commercial lead-acid batteries. Significant insight into the Zn-storage mechanism in the pyrovanadate cathodes is presented using multiple analytical methods. In addition, it is shown that our prototype device can power a 1.5 V temperature sensor for at least 24 h.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.201907798

Rechargeable Aqueous Zinc-Ion Battery Based on Porous Framework Zinc Pyrovanadate Intercalation Cathode.

Titanium Dioxide Nanomaterials for Sensor Applications

Effect of preheating temperature on structural and optical properties of zno thin films by sol–gel process

Electrical and optical properties of Al-doped ZnO thin films by sol–gel process

Nanostructured TiO2–SnO2 thin films have been prepared using a sol–gel process and the humidity sensing properties of the films were investigated. The films possess nano-sized grains and nanoporous structure. The TiO2–20 wt.% SnO2 film exhibits the highest sensitivity for the humidity, which shows over three orders change in the resistance during the relative humidity (RH) variation from 20 to 90%. The high humidity sensitivity is due to the protonic and electrolytic conduction between hydroxyl ions and water molecules adsorbed on the film surfaces with capillary nanopores.

Fabrication and humidity sensing properties of nanostructured TiO2-SnO2 thin films

Growth of Al-doped ZnO thin films by pulsed DC magnetron sputtering

Nanocrystalline Al-doped ZnO(AZO) thin films prepared by sol–gel method were used for studying the variation of resistance with humidity. The particle size of the films exhibits nanometer order with zincite structure and the thickness of the films increases linearly with the number of coatings. The AZO film coated five times and annealed at 500 °C exhibits the highest sensitivity for the humidity, which shows three order change in the resistance during the relative humidity variation from 20 to 90%. It is considered that the high humidity sensitivity is due to proton hopping between water molecules adsorbed on the film surfaces with capillary nanopores.

Weon-Pil Tai

Papers

Effect of preheating temperature on structural and optical properties of zno thin films by sol–gel process

Electrical and optical properties of Al-doped ZnO thin films by sol–gel process

Fabrication and humidity sensing properties of nanostructured TiO2-SnO2 thin films

Growth of Al-doped ZnO thin films by pulsed DC magnetron sputtering

Humidity sensing behaviors of nanocrystalline Al-doped ZnO thin films prepared by sol–gel process