Exploration of New 2D Materials and Their New Properties

Hui-Ming Cheng* 

Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China

Faculty of Materials Science and Energy Engineering, Shenzhen University of Advanced Technology, Shenzhen, China

Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China

*E-mail: hm.cheng@siat.ac.cn

Abstract: Identification of two-dimensional (2D) materials in the monolayer limit has led to discoveries of new phenomena and unusual properties. In this lecture, I’ll first report the growth of large-area high-quality 2D ultrathin Mo₂C crystals by CVD [1], which show 2D characteristics of superconducting transitions that are consistent with Berezinskii–Kosterlitz–Thouless behaviour and show strong dependence of the superconductivity on the crystal thickness. Furthermore, when we introduce elemental silicon during CVD growth of nonlayered molybdenum nitride, we have grown centimeter-scale monolayer films of MoSi₂N₄ which does not exist in nature and exhibits semiconducting behavior, high strength, and excellent ambient stability [2]. On the other hand, we have found some interesting properties from well-known 2D materials such as h-BN. For example, a class of membranes assembled with 2D transition-metal phosphorus trichalcogenide nanosheets give exceptionally high ion conductivity and superhigh lithium ion conductivity [3]. We even demonstrate an anomalously large magneto-birefringence effect in transparent suspension of magnetic 2D crystals [4], with orders of magnitude larger than that in previously known transparent materials. Moreover, based on this phenomenon, we develop a stable and birefringence-tunable deep-ultraviolet modulator from 2D hexagonal boron nitride which gives rise to a ultra-high specific magneto-optical Cotton–Mouton coefficient, about five orders of magnitude higher than other potential deep-ultraviolet-transparent media [5]. Very recently, we have found that strong bulk van der Waals materials can be densified from their nanosheets at near room temperatures with mediation of water [6]. These findings indicate a great promise of 2D materials.

[1] C. Xu et al., “Large-area high-quality 2D ultrathin Mo2C superconducting crystals”, Nature Materials 14, p. 1135 (2015).

[2] Y. L. Hong et al, “Chemical vapor deposition of layered two-dimensional MoSi2N4 materials”, Science 369, p. 670 (2020).

[3] X. T. Qian et al, “CdPS3 nanosheets-based membrane with high proton conductivity enabled by Cd vacancies”, Science 370, p. 596 (2020).

[4] B. F. Ding et al, “Giant magneto-birefringence effect and tuneable colouration of 2D crystal suspensions”, Nature Communications 11 (1), p. 3725 (2020).

[5] H. Xu et al, “Magnetically tunable and stable deep-ultraviolet birefringent optics using two-dimensional hexagonal boron nitride”, Nature Nanotechnology 17, p.1091 (2022).

[6] J. Y. Zhu et al, “Near-room-temperature water-mediated densification of bulk van der Waals materials from their nanosheets”, Nature Materials doi.org/10.1038/s41563-024-01840-0 (2024).

Bio: 

Hui-Ming Cheng

Chair Professor and honorary dean of Faculty of Materials Science and Energy Engineering, Shenzhen Institute of Advanced Technology

Director of Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, CAS
E-mail: hm.cheng@siat.ac.cn

His research activities mainly focus on energy materials and devices, carbon nanotubes, graphene and other 2D materials. He has published over 950 papers with an h-index of 166, and is a Highly Cited Researcher in three fields of materials science, chemistry, and environment and ecology. He has given over 230 plenary/keynote/invited lectures at various conferences, and won 4 State Natural Science Award of China (2nd class), Charles E. Pettinos Award from American Carbon Society, Felcht Award from SGL, Germany, and ACS Nano Lecture Award from ACS. He is the founding Editor-in-Chief of Energy Storage Materials since 2015.