Carbon-coated vanadium dioxide nanoparticles and preparation method thereof

Abstract

The invention relates to carbon-coated vanadium dioxide nanoparticles and a preparation method thereof. The particles consist of rutile-phase nano vanadium dioxide kernels and carbon shells covering the rutile-phase nano vanadium dioxide kernels, wherein the rutile-phase nano vanadium dioxide kernels are approximately square nanoparticles with a length-diameter ratio of being less than 3 and a three-dimensional size of being less than 100 nm; the thickness of the carbon shells are 1-10 nm; the carbon shells account for less than 20 percent by weight of the mass fraction of the particles. The preparation method comprises the following steps: synthesizing the rutile-phase vanadium dioxide nanopowder by using hydrothermal reaction; adding a carbon source into hydrothermal reaction liquid; then performing hydrothermal reaction to perform in-situ carbon coating. The carbon-coated vanadium dioxide nanopowder has superior thermochromic performance, good stability, low cost and high yield and is suitable for large-scale production. The nanopowder can be widely applied to energy-saving coatings, flexible energy-saving films or energy-saving glass of buildings and automobiles.

Description

technical field [0001] The invention belongs to the field of functional nanocomposite materials, in particular to a carbon-coated vanadium dioxide nanoparticle and a preparation method thereof, which can be used for building and automobile energy saving. Background technique [0002] Energy saving and emission reduction has become the top priority at home and abroad. It is estimated that more than 1 / 3 of the total energy consumption of the society is energy consumption of buildings. Since most of the air-conditioning energy in building energy consumption is lost by windows, the development of new energy-saving windows, especially intelligent energy-saving windows that can adjust the transflective characteristics according to seasons and human needs, can achieve maximum comfort while saving energy and environmental protection Living Environment. [0003] Among all kinds of energy-saving windows, the thermochromic smart energy-saving glass developed by using the huge optical...

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Problems solved by technology

Although the particles are nanoscale in the short axis direction, the long axis direction is far beyond the nanoscale to the micron range, which will bring two problems: ① Due to the strong absorption of vanadium dioxide for visible light, the larger the particle size , the greater the absorption

Calculations show that when VO 2 When the thickness of the material is greater than 100nm, the transmittance of visible light will only be about 20%, which is difficult to meet the basic requirements of smart energy-saving glass (Xu G., Jin P., Tazawa M.Yoshimura K.; Appl.Surf.Sci.244 (2005) pp.449-452), and the long-diameter dimension of the tape-shaped material obtained by this method is on the order of microns; Broken or broken, the fracture is easily oxidized without the protection of the coating material, which reduces the stability of the material

③The dispersion performance of strip-shaped materials is far inferior to that of equirectangular materials, which brings a lot of inconvenience to the processing and preparation process;

[0016] 2) This method uses pre-synthesized band-shaped precursor vanadium compound and dried it to coat the carbon material, and then convert it into M-phase VO with the same shape by subsequent means such as calcination. 2 Particles, the process is complex and difficult to control, it is difficult to avoid particle size increase and particle size distribution caused by particle growth and sintering during the calcination process, which affects the final performance of the material, and the complicated process is obviously not conducive to saving costs

Moreover, the actual carbon content in the material prepared by this method is high, resulting in low transmittance, which is not suitable for the field of energy-saving windows.

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