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Defect‐Engineered Atomically Thin MoS2 Homogeneous Electronics for Logic Inverters

2019-11-19T20:32:53+00:00November 19th, 2019|Categories: Publications|Tags: , |

Accurate and facile solution‐processable defect engineering is proposed for constructing atomic‐thin MoS2 homogeneous electronics. By utilizing the energy‐matched relationship between the formation energy of monosulfur vacancies (Vmonos) and the electron induction energy of H2O2 aqueous solution, numerous pure and lattice‐stable Vmonos are introduced for modulating electronic structure to construct homogeneous electronics including logic inverter via shallow trapping effect. Abstract Ultrathin molybdenum disulfide (MoS2) presents ideal properties for building next‐generation atomically thin circuitry. However, it is difficult to construct logic units of MoS2 monolayer using traditional silicon‐based doping schemes, such as atomic substitution and ion implantation, as they cause lattice disruption and doping instability. An accurate and feasible electronic structure modulation strategy from defect engineering is proposed to construct homogeneous electronics for MoS2 monolayer logic inverters. By utilizing the energy‐matched electron induction of the solution process, numerous pure and lattice‐stable monosulfur vacancies (Vmonos) are introduced to modulate the electronic structure of monolayer MoS2 via a shallow trapping effect. The resulting modulation effectively reduces the electronic concentration of MoS2 and improves the work function by 100 meV. Under modulation of Vmonos, an atomically thin homogenous monolayer MoS2 logic inverter with a voltage gain of 4 is successfully constructed. A brand‐new and practical design route of defect modulation for 2D‐based circuit development is provided.

Published in: "Advanced Materials".

Atomistic mechanisms of seeding promoter-controlled growth of molybdenum disulphide

2019-11-19T12:32:42+00:00November 19th, 2019|Categories: Publications|Tags: |

Seeding promoters facilitate the nucleation and growth of transition metal dichalcogenides in chemical vapor deposition (CVD). However, sophisticated roles of seeding promoter remain unclear. Here, adopting triangular-shaped crystal violet (CV) consisting of nonpolar and polar parts as the seeding promoter, we study the role of seeding promoter for the growth of molybdenum disulfide (MoS 2 ). We systematically control the geometrical configuration of CV on SiO 2 /Si substrate by changing the solvent polarity and find that it strongly affects the growth of monolayer or multilayer MoS 2 domains via CVD. Monolayer MoS 2 domains were predominantly grown on randomly lying-down CV configurations on SiO 2 /Si substrate, whereas multilayer MoS 2 domains are synthesized at concentrated polar parts in CV micelle on the substrate. Density functional theory calculations reveal that the initial nucleation step for the MoS 2 g…

Published in: "2DMaterials".

Low-voltage 2D materials-based printed field-effect transistors for integrated digital and analog electronics on paper. (arXiv:1911.06233v1 [physics.app-ph])

2019-11-15T04:30:16+00:00November 15th, 2019|Categories: Publications|Tags: |

Paper is the ideal substrate for the development of flexible and environmentally sustainable ubiquitous electronic systems, enabling new applications in the context of the Internet of Things (IoTs). Two-dimensional materials have outstanding electronic and optical properties, and they are compatible with flexible substrates. Besides, combining different 2D materials enables to design a large variety of devices, which could be exploited in many IoTs applications, ranging from wearable electronics to smart packaging. In this work, we demonstrate high-performance MoS2 field-effect transistors on paper substrates fabricated with a new channel-array approach, which combines the advantages of chemical vapor deposition (CVD) and inkjet-printing as fabrication techniques. This method is based on the preparation of a channel array, i.e., the pre-deposition on paper of a pattern of CVD-grown MoS2 to be used as channels. Inkjet printing is then used to complete transistors and circuits fabrication, through the deposition of dielectric layers, contacts, and connections. We show that the channel-array approach allows the fabrication of 2D materials-based transistors on paper with excellent current modulation (ION to IOFF ratio up to 100000) and mobility (up to 15 cm2 V-1 s-1). Fully functional integrated circuits of digital and analog building blocks, such as high-gain inverters, logic gates, and current mirrors are demonstrated, confirming the potential of this approach for ubiquitous electronics on paper.

Published : "arXiv Mesoscale and Nanoscale Physics".

A Universal Seeding Strategy to Synthesis Single Atom Catalysts on 2D Materials for Electrocatalytic Applications

2019-11-15T02:33:18+00:00November 15th, 2019|Categories: Publications|Tags: , , , |

A facile, controllable, and scalable method is developed for the fabrication of single‐atom catalysts (SACs) on various 2D materials supports with high loading and activities via a new seeding approach, significantly accelerating the practical application of SACs for the areas of electrocatalysis and catalysis. Abstract Single‐atom catalysts (SACs) are attracting significant attention due to their exceptional catalytic performance and stability. However, the controllable, scalable, and efficient synthesis of SACs remains a significant challenge. Herein, a new and versatile seeding approach is reported to synthesize SACs supported on different 2D materials such as graphene, boron nitride (BN), and molybdenum disulfide (MoS2). This method is demonstrated on the synthesis of Ni, Co, Fe, Cu, Ag, Pd single atoms as well as binary atoms of Ni and Cu codoped on 2D support materials with the mass loading of single atoms in the range of 2.8–7.9 wt%. In particular, the applicability of the new seeding strategy in electrocatalysis is demonstrate on nickel SACs supported on graphene oxide (SANi‐GO), exhibiting excellent catalytic performance for electrochemical CO2 reduction reaction with a turnover frequency of 325.9 h−1 at a low overpotential of 0.63 V and high selectivity of 96.5% for CO production. The facile, controllable, and scalable nature of this approach in the synthesis of SACs is expected to open new research avenues for the practical applications of SACs.

Published in: "Advanced Functional Materials".