Hydrogen energy is considered as the most promising renewable sources of energy to substitute fossil fuels. It has the advantages of zero-greenhouse emission, abundant resources, and high energy density. The electrocatalytic hydrogen evolution reaction (HER) using water splitting has received intense interest as an environmental-friendly technology consisting of HER and water oxidation reaction (WOR). Although the HER is a clean technology, it requires a high electric energy consumption and a high energetic efficiency. Thus, increasing the photocatalytic efficiency of HER is significantly necessary.

Ammonia (NH3) is a colorless and toxic gas, which has a pungent odor. which has a pungent odor. This compound has been widely used in agriculture, fertilizer, factories, food processing, power plants, refrigeration systems, medical treatments, and living environments. Inhalation of ammonia may cause various acute respiratory diseases. It is proved that exposure to ammonia above 50 ppm can irritate the eyes, nose, throat and skin, and extended exposure to ammonia above 200 ppm may even cause chemical burns of skin and permanent lung damage. Thus, the development of ammonia sensors is very significant in the applications of environmental monitoring, industrial process control, and food industry and medical diagnostics. The sensing materials of resistant-type ammonia sensors mainly include semiconducting metal oxides, carbon nanomaterials and conducting polymers.

A lot strategies had been applied to improve the enactment of lithium-ion batteries (LIBs) for next-generation electric vehicles (EVs). However, improving the energy density of LIBs is key extend the driving range of current EVs. Graphite has been broadly employed as the industrial standard LIBs anode material. However, graphite suffers from low theoretical capacity. Tungsten disulfide (WS2) is a transmission metal oxide which reveals trigonal prismatic structure and are indirect gap semiconductors in the bulk form with a bandgap of 1∼1.3 eV in the single-layer. This feature is used in a variety of fields, including energy storage, catalysis, solar cell, sensing, and electronic devices.

Air quality monitoring and toxic gas emissions had risen to be a global concern in the past decades. Researchers have been trying various and massive strategies to find an effective gas sensor and its synthesis methods in this field. A practical gas sensor should detect a particular gas among a mixture of gases and continuously monitor an atmosphere. There are many types of gas sensors depend on different classification methods.

W–Cu composite combine high electrical and thermal conductivity of Cu and high arc corrosion resistance, hardness, and low thermal expansion coefficient of tungsten, and show excellent properties. Due to the distinct performance, W–Cu composites have found potential applications in electronic packaging, electric contact, aerospace, and some other high-tech areas. However, in some severe working environments, such as aerospace, micro electric manufacturing, etc, may face the issues of low relatively density and inhomogeneous microstructure.

The mechanical properties of carbon nanotube composites are mainly studied by experiment, theoretical analysis and numerical method. The common methods for the mechanical properties of carbon nanotubes include amplitude calculation, cantilever/simply supported beam model, and direct methods. The mechanical parameters of carbon nanotubes are derived by classical mechanics.Solid acid catalysts play a significant part in chemical and petroleum industries in hydrocarbon conversion reactions required in octane enhancement processes, such as cracking, isomerization and alkylation, which can form highly branched isoparaffins. Such reactions need strong or moderate acid catalysts.

WC-Co cemented carbide has widely used in machining, drilling, automotive, military, and aerospace owing to its excellent mechanical performances. Most research on cemented tungsten carbides with a cobalt binder (WC-Co cemented carbides) has focused on improving their strength, fracture toughness, and hardness.

As the demands for solar energy, pure air and water, and disposing of poisonous and hazardous pollutant are increasing, the use of semiconductor photocatalysts for environmental purification has attracted considerable attention due to their applicability for the removal of a wide variety of pollutants. Especially TiO2 has been studied widely in virtue of the high photocatalytic activity for organic pollutants such as RhB, tetracycline, phenol, and methylene blue under UV irradiation. Although TiO2 has various merits, the practical application of TiO2 is limited by its low photon utilization efficiency and the need for an ultraviolet excitation source which accounts for only a small fraction of solar light (approximately 5%).

Currently, due to the environmental situation worsening, in various countries and especially in the large cities, more and more funds have been allocated for the development of the green energy industry and environmentally friendly technologies. Hydrogen energy is an energy source that has increased its popularity in recent years. It is a clean energy source that can be used instead of fossil fuels. Hydrogen it can be used instead of fossil fuels due to its higher energy content and less environmental impact. The density of hydrogen is lower than the density of air. The gravimetric density of hydrogen energy is generally about seven times higher than the density of fossil fuels.