Graphene is a new type of carbon material, and is currently the thinnest and hardest nanomaterial in the world. It has excellent characteristics in terms of thermal conductivity, electrical conductivity, light transmission properties, and gas barrier properties. Therefore, graphene is also called "dream material." From the current macroscopic morphology and number of graphene products, graphene products can be divided into oligo-graphene powders and large-area single-layer graphenes.
The former mainly use chemical redox or mechanical stripping method for preparation, potential applications for composite materials, conductive inks, sensors and battery electrodes. The latter is mainly obtained by chemical vapor deposition, and the potential application field is a transparent touch screen. At present, both types of products have undergone intense competition for industrial research, and competition in the field of oligo-layered graphene powders has been particularly intense. However, the current high price severely limits the application of graphene, and the development of low-cost and high-quality graphene is currently the focus of research.
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, has made a series of progress in the preparation and application of graphene. In 2012, the "Graphene Preparation Technology" of Liu Zhaoping's team successfully transferred. The method is based on graphite as a raw material, prepared by chemical methods. The successful development of this technology has a certain role in promoting the preparation and application of graphene.
In recent years, "bio-based synthetic materials" have rapidly developed into an emerging and promising field in the world. The Zhujin team of the Ningbo Institute of Materials has earlier conducted research on "bio-based polymer materials" in the country and developed soybean-based aldehyde-free products. Rubber and heat-resistant polylactic acid products, and successfully achieved industrialization and marketization. Based on this, the team found that using low-cost biomass carbon sources such as lignin and cellulose as raw materials successfully produced high-purity and high-quality bio-based graphene, and the cost was significantly reduced compared with the traditional graphite stripping method. Has applied for two Chinese patents (CN 201310721586.6 and CN 201410071766.9), and more new patents are being applied. The macroscopic state of the bio-based graphene is a fluffy black powder (as shown in FIGS. 1a and 1b). In Fig. 1c, the bio-based graphene shows the translucency unique to the oligo-graphene under the transmission electron microscope TEM observation.
According to the statistics of many samples, the typical two-dimensional plane size is between 0.5-2μm. In addition, the product has a specific surface area in the range of 400-1000 m2/g as measured by gas adsorption BET method. In the Raman spectrum of FIG. 1d, the bio-based graphene shows a lower ID/IG peak ratio, indicating that the product has a higher degree of graphitization and fewer defects. In addition, sharp 2D peaks were found near 2700 cm-1, indicating that the average number of graphene fines is small. The above experimental evidence shows that the quality of bio-based graphene is very good. Utilizing the unique dispersion technology of the Yu Haibin team of Ningbo Institute of Materials, bio-based graphene has significantly improved the anti-corrosion performance of the coating (as shown in Figure 2).
The emergence of bio-based graphene breaks the current state that graphene products must use graphite or petrochemical resources as a carbon source, and realizes the sustainable development of graphene product raw materials. And this innovation in raw materials has also brought a lot of preparation technology innovation, process innovation, so that the price of graphene from a few thousand dollars a kilogram, down to several hundred dollars a kilogram. In general, the emergence of low-cost bio-based graphene products has opened up new production methods for the graphene industry and opened up broad application prospects.
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