Growth and synthesis of graphene-based superlattices in space-limited growth and its magnetocaloric effect Recently, professor Xie Yi of the University of Science and Technology of China has made new progress in the synthesis and application of graphene-based superlattice materials. Using space-bound growth strategies, the researchers for the first time synthesized vanadium-oxygen framework-graphene superlattice materials in solution and demonstrated a significant increase in magnetocaloric effects. The results were published online at Nature Communications. It is well-known that superlattice materials have attracted considerable interest in recent years because of their unusual physical properties due to their special interface electronic structure. However, conventional superlattice materials are usually obtained by expensive pulsed laser deposition or molecular beam epitaxy. This also means that the subsequent practical application requires a complicated process to transfer the obtained superlattice from the growth substrate. At the same time, the latest research results show that graphene has unique bipolar electronic properties. When compounded with other materials, it can be used as an electron donor or electron acceptor to effectively regulate the electrical properties of materials. Therefore, graphene-based supercrystals Due to the special interfacial properties of the superlattice and the unique electronic structure of graphene, the lattice material may bring about a series of new materials that do not exist in traditional materials. In response to the above challenges, the research group first proposed a new method for the growth of graphene-based superlattice materials by a space-limited growth strategy, and obtained a perfectly stacked monolayer graphene-monolayer vanadium oxide-monolayer graphene. The superlattice structure overcomes the disadvantages of the conventional grown superlattice materials. In this graphene-based superlattice material, graphene can not only be used as a unique space-restricted reactor to make the vanadium-oxygen layer grow two-dimensionally along the graphene surface, but also as an electron donor, resulting in a vanadium-oxygen layer structure. The structural reorganization reduces the generation energy of the highly symmetric vanadium oxygen skeleton. The research group cooperated with Prof. Wei Shiqiang of the National Synchrotron Radiation Laboratory and used the synchrotron X-ray absorption fine structure spectrum to characterize the fine structure of the superlattice in detail. The results show that the symmetry of the vanadium-oxygen layer in the superlattice is significantly greater than that of the VO2 (B) obtained in free space and leads to the appearance of a first-order reversible phase transition and the resulting magnetocaloric effect. This phase transition is similar to The symmetry of VO2(M)-VO2(R) transitions from high to low. Due to the two-dimensional monodomain structure in the superlattice and the stress effect of the graphene layer, the magnetic entropy change value in this transition process is increased compared to the magnetic entropy change value of the VO2(M)-VO2(R) phase transition. Times. It is important that this flexible superlattice nanosheet material is prepared by a low-cost solution method, which avoids the complicated transfer process in the preparation of a conventional superlattice material, and is therefore suitable for the assembly of various functional devices and is expected to accelerate super The practical application of lattice materials. Shenzhen Zhuohao Intelligent Electronic Development Co., Ltd. , https://www.szactop-smart.com
China University of Science and Technology proposes a new strategy for the preparation of graphene-based superlattice materials