The Electronic and Magnetic Properties of Multi-Atom Doped Black Phosphorene

Characteristics and performance of layered two-dimensional materials under doping engineering

In recent years, doping engineering, which is widely studied in theoretical and experimental research, is an effective means to regulate the crystal structure and physical properties of two-dimensional materials and expand their application potential. Based on different types of element dopings, different 2D materials show different properties and applications. In this paper, the characteristics and performance of rich layered 2D materials under different types of doped elements are comprehensively reviewed. Firstly, 2D materials are classified according to their crystal structures. Secondly, conventional experimental methods of charge doping and heterogeneous atom substitution doping are summarized. Finally, on the basis of various theoretical research results, the properties of several typical 2D material representatives under charge doping and different kinds of atom substitution doping as well as the inspiration and expansion of doping systems for the development of related fields are discussed. Through this review, researchers can fully understand and grasp the regulation rules of different doping engineering on the properties of layered 2D materials with different crystal structures. It provides theoretical guidance for further improving and optimizing the physical properties of 2D materials, improving and enriching the relevant experimental research and device application development.

Effect of non-magnetic doping on magnetic state and Li/Na adsorption and diffusion of black phosphorene

Black phosphorene (BP) have aroused great concern because of its great potential for the application in nanoelectronic devices and high-performance anode materials for alkali metal ion batteries (AIBs). However, the absence of magnetism for an ideal BP limits its wide application in spintronic devices which is one of the important nanoelectronic devices, and its application as a high-performance anode material for AIBs is still to be explored. In this paper, we adopt first-principles calculations to explore the effects of B, C, N, O, F, Al, Si and S atom doping on the magnetic state of monolayer BP and Li or Na atom adsorption and diffusion on the BP. Additionally, the thermal stability of the doped BP systems at room temperature is revealed by theab initiomolecular-dynamics calculations. Our calculated results indicate that O and S doping can make the doped BP become a magnetic semiconductor, C and Si doping makes the doped BP be metallic, and B, N, F and Al doping preserves semiconductor property. Moreover, little structural changes and significant decreases of diffusion barriers in armchair direction and slight increases of diffusion barriers in zigzag direction make B-doped BP beneficial as an anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). It reveals that S-doping is suitable for improving the performance of SIBs rather than LIBs. Interestingly, it is found that magnetic states of O- and S-doped BP disappear when Li or Na atoms adsorb on them, whereas Li or Na adsorption on B- and Al-doped BP induces magnetic states of these systems. The analyses indicate that the distinct electron transfer between the dopant atom, adatom and neighboring P atoms, and specific electron configuration of dopant atoms cause the magnetism of the systems. Our results suggest that selecting appropriate composition to dope can effectively manipulate magnetic state and improve Li/Na adsorption and diffusion on the BP. These results may inspire further theoretical and experimental exploration on doped two-dimensional (2D) materials in spintronics and doped 2D promising anode materials for high-performance metal ion batteries.

Photo-exfoliation of MoS2quantum dots from nanosheets: anin situtransmission electron microscopy study

Fabrication of transition metal dichalcogenide quantum dots (QDs) is complex and requires submerging powders in binary solvents and constant tuning of wavelength and pulsed frequency of light to achieve a desired reaction. Instead of liquid state photoexfoliation, we utilize infrared laser irradiation of free-standing MoS₂flakes in transmission electron microscope (TEM) to achieve solid-state multi-level photoexfoliation of QDs. By investigating the steps involved in photochemical reaction between the surface of MoS₂and the laser beam, we gain insight into each step of the photoexfoliation mechanism and observe high yield production of QDs, led by an inhomogeneous crystalline size distribution. Additionally, by using a laser with a lower energy than the indirect optical transition of bulk MoS₂, we conclude that the underlying phenomena behind the photoexfoliation is from multi-photon absorption achieved at high optical outputs from the laser source. These findings provide an environmentally friendly synthesis method to fabricate QDs for potential applications in biomedicine, optoelectronics, and fluorescence sensing.