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The invention discloses a method for preparing a single-layer tungsten diselenide nanoband based on a space confinement strategy. By changing the flow and the growth time of hydrogen, effective control on the width and the thickness of a nanoband can be realized. The method comprises the following steps: uniformly spraying tungsten trioxide powder to one substrate, then covering the substrate by the other substrate, and forming micro reaction space which is of a 'sandwich'-like structure. Growth of a tungsten diselenide nanoband is carried out by utilizing a constant-pressure chemical vapor deposition method; physicochemical characteristics of a one-dimensional transition metal chalcogenide strongly depend on suspension key types on the edge of the one-dimensional transition metal chalcogenide, metallic properties are displayed by an ultranarrow band, and conversion from the metallic properties to semiconductor properties can be displayed from the edge to the center of a wider band; the tungsten diselenide nanoband is widely applied to micro-nano photoelectric devices due to the special property; industrial production of the tungsten diselenide nanoband can be realized through an experimental method of the invention.

The invention discloses a novel synthetic method for 5-phenyl tetrazole, which includes the following steps: firstly performing acid neutralization to hydrazine hydrate; then adding mixing solution formed by cyanobenzene, water and ethyl alcohol to generate phenyl aminoguanidine salt; adopting sodium nitrite for diazotization to obtain nitrine amidine under the acidic condition; obtaining 5-phenyl tetrazole crude product through closed loop under the alkaline condition; obtaining 5-phenyl tetrazole acceptable product through adopting ethyl alcohol for refining. The method has the advantages of simple technology, simplicity in operation and high product yield.