Electrochromism refers to the phenomenon that the optical properties of materials change reversibly under the action of external electric field. Electrochromism only needs a small voltage (about 2V) to work. In the open circuit state, it can keep the original color or fading state unchanged, so it consumes less energy.

Tungsten trioxide electrode and its preparation method, and its application in photo catalytic decomposition of water use semiconductor photo catalytic technology to convert solar energy into hydrogen energy through water decomposition, and store and use hydrogen in the form of chemical energy, is one of the most promising ways to solve the current energy crisis.

Generally, violet tungsten oxide is obtained by calcining ammonium paratungstate in a rotary furnace. The prepared violet tungsten oxide is ultrafine and of good quality. During the preparation process, furnace temperature, furnace tube speed and feeding speed are the three factors that affect the properties of violet tungsten oxide.

Violet tungsten oxide is powder with unique structure of needle. It is composed of many different components. The components and their quantities are determined by the specific preparation method. Violet tungsten oxide has some alternate names -γ-tungsten oxide, for example.

Violet tungsten oxide with low apparent density has high application value in the field of powder metallurgy. It is an extremely important material for the preparation of ultrafine tungsten powder and tungsten carbide. Low apparent density of violet tungsten oxide is determined by its unique needle structure.

PEC technology is based on solar energy and water, both of which are renewable. PEC technology has no by-products and will not bring pollution to the environment. Moreover, PEC technology can be applied in small scale and developed in large scale. Therefore, this technology is the most attractive way to produce hydrogen directly by solar energy.

Silver nickel electrical contact has been widely used in various low-voltage electrical appliances because of its good thermal conductivity, low and stable contact resistance, excellent processing performance and other advantages. However, due to its poor anti fusion welding performance, the application range of silver nickel electrical contact is affected.

Cathode materials have been the bottleneck to improve the performance and reduce the cost of lithium-ion batteries. Lithium iron phosphate is the first choice of cathode materials for modern commercial lithium-ion batteries because of its low price, high energy density, long life and good safety. However, the low electronic conductivity of lithium iron phosphate seriously hinders its application in the field of power and energy storage batteries.

Tungsten disulfide (WS₂) is a kind of layered solid lubricant with structure similar to graphite. It has excellent high temperature resistance, extreme pressure resistance, good adsorption capacity on metal surface and low thermal conductivity. WS₂ was first applied to the lubrication of the key parts of the American mariner spacecraft, and it was used to prepare high temperature extreme pressure grease and energy-saving engine lubricating oil, with good application results.

At present, China's major cities are booming in the construction of rail transit projects. Because of its unparalleled advantages, shield method has been widely used in the construction of rail transit tunnels.