Prof. Yang Shubin’s research group in the School of Materials Science and Engineering of Beihang University, published an article entitled “Conversion of non-van der Waals solids to 2D transition-metal chalcogenides” online in Nature recently, reporting the latest progress on 2D materials. PhD candidate Du Zhiguo and Prof. Yang Shubin of Beihang Univeristy are the first and corresponding authors respectively.
In this article, a brand-new strategy to synthesize 2D materials was put forward — topological transformation, which converts non-van der Waals (non-vdW) solids such as MAX phases to 2D vdW transition-metal chalcogenide layers with identified 2H (trigonal prismatic)/1T (octahedral) phases. It is anticipated that these 2D transition-metal chalcogenides will be widely applied to electronics, catalysis and energy storage.
Prof. Yang Shubin’s latest research published in Nature
The effective strategy proposed by prof. Yang’s group overcomes the long-standing problem in producing air-stable 2D materials. The schematic illustration of the conversion of non-vdW solids to 2D vdW transition-metal chalcogenides is depicted in Fig.1. Because the M–A bonds are more chemically active than the M–X bonds, as depicted in Fig.1a, under chalcogen-containing vapours (HyZ, where Z represents sulfur, selenium or tellurium andy is 0 or 2) at high temperatures (873-1372K), non-vdW MAX phases and transition-metal borides, silicides and carbides have high activities. In particular, the active M–A bonds in MAX phases react easily with chalcogen-containing gases, resulting in products of AZ and MZ compositions. The topological transformation, achieved by exposing non-vdW solids to chalcogen vapours, can be controlled by enthalpies and vapour pressures of the reaction products. Regulating the compositions of MAX phases (ternary or quaternary MAX phases) and introducing a third reactant (P vapour) enable such an approach to engineering phase-selected 2D transition-metal chalcogenide structures with good stability at high temperatures (up to 1,373 kelvin) and achieving high-throughput production of monolayers.
Fig. 1 Schematic illustration of the conversion of non-vdW solids to 2D vdW transition-metal chalcogenides. a, Non-vdW solids such as MAX phases are progressively transformed to 2D transition-metal chalcogenides via a topological conversion reaction (MAX + HyZ (gas)→MZ + AZ). b, Temperature–vapour pressure relationships for various AZ substances
Prof. Wei Sun Leong of National University of Singapore published a comment on the work of Prof. Yang in Nature. He pointed out that this method can directly transform non-van der Waals (non-vdW) solids into TMC monolayers. With advantages of low-cost, ease of operation, etc., this method for producing air-stable 2D materials on an industrial scale is a key step in bringing them to market. He commented that “From a scientific standpoint, 2D materials need to be stable and usable in our immediate surroundings. Du and colleagues’ findings are promising for the field because they show that the presence of a low quantity (less than 1%) of impurity atoms can stabilize TMC monolayers.”
Prof. Wei Sun Leong’s comment published in Nature
The research, which adopted various advanced testing and characterization methods, was collaborated by 11 participators from four institutions: Prof. Yang Shubin’s team of Beihang University, Prof. Pulickel M. Ajayan of Rice University, Prof. Zou Xiaolong’s team of Tsinghua University, and Prof. Song Li of University of Science and Technology of China.
This work was supported by the National Natural Science Foundation of China, the Youth 1000-Talent Program of China and the 111 Project, etc.
More information of the research:
Reported by Shi Yue
Reviewed by Li Jianwei
Edited by Jia Aiping
Translated by Ren Chenjie