A scientific research team at Tianjin University guided by Professor Feng Wei has develped the first light-sensitive molecules and Nano template assembly in the world. It is used for the production of new hybrid material, which makes single or dual azobenzene molecules covalently bound to reduced graphene oxide. This result overcomes the problem of solar-heat storage and tuneable heat release in molecules, which paves the way for the development of significant materials in energy-dense and thermal stable solar-heat storage and conversion in the future. The related research results were published in online Journal of Materials Chemistry, a leading publication in the field of material chemistry.

As a new technology, the direct solar-heat conversion and storage can change the traditional energy utilization method and provide clean and stable energy for us. The key difficulty for the scientists regarding this technology lies in the designing of materials that can store the solar and heat energy in chemical molecules. However, Professor Feng’s research team have taken the lead in producing the azobenzene and grapheme hybrid material, a new chemical heat storage material at the molecular level that can directly process “solar storage--heat release”. The experimental results show that the energy density of the azobenzene and grapheme hybrid material is twice or three times as high as those of existing materials. It has reached 138Wh/kg, the maximum among all other international reports.

This material combines the performances of cycled solar-heat storage and tuneable heat release with an ability of about 50 cycled solar-heat storage times, meaning a continuous use time of four and a half years.

Then how can the heat release be tuneable? Professor Feng explains that the azobenzene molecules are grafted in grapheme as an “optical switch” and “eyes”. As a result, the grapheme can see and be tuneable by light with the help of its eyes to absorb and store the solar energy and release the heat.