Li Tao

Southeast University | SEU · School of Materials Science and Engineering

Size and shape are fundamental properties of micro/nanoparticles that are critically important for nanomedicine applications. Extensive studies have revealed the effect of particle size on spherical particles with respect to circulation, extravasation and distribution in vivo. In contrast, the importance of particle shape has only recently begun to...

We report new findings on the chemical vapor deposition (CVD) of monolayer graphene with negligible defects (≥95% negligible defect-peak over 200 μm × 200 μm areas) on evaporated copper films. Compared to copper foils used in the CVD of graphene, several new unexpected results have been observed including high-quality monolayer synthesis at tempera...

Free-standing silicene, a silicon analogue of graphene, has a buckled honeycomb lattice and, because of its Dirac bandstructure combined with its sensitive surface, offers the potential for a widely tunable two-dimensional monolayer, where external fields and interface interactions can be exploited to influence fundamental properties such as bandga...

Silicene, the ultimate scaling of a silicon atomic sheet in a buckled honeycomb lattice, represents a monoelemental class of two-dimensional (2D) materials similar to graphene but with unique potential for a host of exotic electronic properties. Nonetheless, there is a lack of experimental studies largely due to the interplay between material degra...

Two‐dimensional (2D) transition metal dichalcogenides (TMDs) are widely used in interfacial reactions and electronic devices due to their tunable bandgap and high efficiency of carrier transport. However, the lack of fully exposed active sites in bulk samples or stacked nanosheets leads to limited performances. In this work, a general method is dev...

Different types of devices with modulable resistance are attractive for the significant potential applications such as sensors, information storage, computation, etc. Although extensive research has been reported on resistance effects, there is still a need for exploring new mechanisms that offer advantages of low power consumption, high sensitivit...

Anti-ambipolar transistors (AATs) are a promising candidate for multivalued logic devices, which are vital for improving the device density and data-handling capabilities of nanoelectronics. Compared with most AATs with Λ-shaped transport characteristics, the emerging four-logic-state bi-AATs have a stronger capability for exponentially increasing...

Photo‐assisted ion batteries utilize light to boost capacity but face cycling instability due to complex charge/ion transfer under illumination. This study identified photo‐induced proton transfer (photo‐induced PT) as a significant process in photo‐(dis)charging of widely‐used V2O5‐based zinc‐ion batteries, contributing to enhanced capacity under...

Photo‐assisted ion batteries utilize light to boost capacity but face cycling instability due to complex charge/ion transfer under illumination. This study identified photo‐induced proton transfer (photo‐induced PT) as a significant process in photo‐(dis)charging of widely‐used V2O5‐based zinc‐ion batteries, contributing to enhanced capacity under...

To ensure optimal performance, ZrNiSn is required to possess a low thermal conductivity and exhibit minimal bipolar effects under high-temperature conditions. This study demonstrates the integration of silicon (Si) at different doping levels into ZrNiSn. The composites consist of secondary phases of in situ ZrNiSi and Si. At a temperature of 873 K,...

The topological insulator 2D Bi2Se3 is promising for electronic devices due to its unique electronic properties; however, it is challenging to prepare antioxidative nanosheets since Bi2Se3 is prone to oxidation. Surface passivation using ligand agents after Bi2Se3 exfoliation works well to protect the surface, but the process is time-consuming and...

Developing composite materials with optimized mechanics, degradation, and bioactivity for bone regeneration has long been a crucial mission. Herein, a multifunctional Mg/Poly‐l‐lactic acid (Mg/PLLA) composite membrane based on the “materials plain” concept through the accumulative rolling (AR) method is proposed. Results show that at a rolling rati...

The application of 2D materials-based flexible electronics in wearable scenarios is limited due to performance degradation under strain fields. In contrast to its negative role in existing transistors or sensors, herein, we discover a positive effect of strain to the ammonia detection in 2D PtSe2. Linear modulation of sensitivity is achieved in fle...

Temperature sensing is of high value in the wearable healthcare, robotics/prosthesis, and noncontact physiological monitoring. However, the common mechanic deformation, including pressing, bending, and stretching, usually causes undesirable feature size changes to the inner conductive network distribution of temperature sensors, which seriously inf...

It has been highly demanded to optimize the charge carrier concentration in 2D Bi2Te3 to achieve enhanced thermoelectric performance. This work reveals that, constructing 2D Bi2Te3/Si heterostructure with tuned interfacial electronic band structure can meet the above needs. When the work function in Si substrate is decreased from 4.6 to 4.06 eV, th...

It is a challenge to obtain high thermoelectric efficiency owing to the conflicting parameters of the materials that are required. In this work, the composition-adjustable 2D bismuth antimonide (Bi100-xSbx) is synthesized using an e-beam evaporation system with homemade targets. Engineering multiscale defects is done to optimize the thermoelectric...

2-D semiconductors are promising Si alternatives for channels in next-generation electronic devices. Considering the 2-D SiP2 with unique dispersion at the band edge and intrinsic P–P chains with 1-D confined electrons, we provide a comprehensive investigation on the electronic and ballistic transport properties of SiP2. Based on firstprinciple and...

Scalable solar-driven H2O2 evolution from water holds great promise for industrial applications. Efficient H2O2 generation relies on excellent spatial charge separation but simultaneously suffers from severe surface H2O2 backreaction, which becomes a bottleneck for scalable H2O2 evolution. Herein, a hydroxyl-induced carbon nitride (CN) homojunction...

Most conventional thermoelectric materials, such as semiconductors, are rigid and brittle, making it difficult for them to endure harsh working conditions, and causing high interfacial heat loss. Cupronickel (Cu-Ni)-based alloys are good candidates for thermoelectric application with outstanding mechanical properties. However, the low Seebeck coeff...

Atomically thin two-dimensional materials synthesized from single atomic species of Group 13–16 elements, known as Xenes, are at the forefront of postgraphene nanoelectronics era. Thanks to their unique physical and chemical properties, they hold promise not only to tackle the issues arising from an aggressive downscaling of silicon devices but als...

Two-dimensional (2D) bismuth has received considerable attention in the past few years due to its unique structure and superior electrical, optical, and topological properties. It is a promising candidate to be applied in innovate field-effect transistors, thermoelectrics, photodetectors, batteries and other electronics, in virtue of the good air s...

In this article, we demonstrate a flexible and wearable hybrid radio frequency (RF) and solar energy harvesting system for powering wearable electronic devices. The system consists of a flexible transparent antenna, a flexible transparent rectifying circuit and an amorphous silicon solar cell. By utilizing transparent stacked structure, the rectenn...

Reliable, wide range, and highly sensitive joint movement monitoring is essential for training activities, human behavior analysis, and human-machine interfaces. Yet, most current motion sensors work on the nano/microcracks induced by the tensile deformation on the convex surface of joints during joint movements, which cannot satisfy requirements o...

Atomic sheets of bismuth (Bi) have been expected to yield exotic optoelectronic properties, holding great promise for photodetector devices. However, existing Bi thin film photodetectors have limited performance in terms of photoresponsivity or response time, hindering its practical application. Herein, we report an experimental research progress o...

ZnO has a large thermal conductivity that hinders its satisfactory thermoelectric performance. In this work, we add multiple dopants including S, C, Fe and Ni to ZnO simultaneously. A low thermal conductivity ∼3 W m⁻¹ K⁻¹ is obtained, with an initial composition ZnO-1%S-0.15%C-4%Fe2O3-3%NiO (sample #7), and comparable to the lowest reported values...

Emerging Xenes, mostly group IVA and VA elemental two‐dimensional (2D) materials, have small and tunable band gaps between graphene and transition metal dichalcogenides, giving versatile electrical properties. While their microelectronic or optoelectronic properties are being extensively explored, there remains a lack of study on Xenes' uniquely ad...

Two-dimensional (2D) bismuth is expected to yield exotic electrical properties for various nanoelectronics, despite of the difficulty in large-area preparation and property tuning directly on a device substrate. This work reports an electron beam (e-beam) evaporation of large-area 2D bismuth directly on SiO2/Si with electrical conductivity of ~105...

This experimental study reveals intriguing thermoelectric effects and devices in epitaxial bismuthene, two-dimensional (2D) bismuth with thickness ⩽30 nm, on Si (111). Bismuthene exhibits interesting anisotropic Seebeck coefficients varying 2-5 times along different crystal orientations, implying the existence of a puckered atomic structure like bl...

Hypospadias is a common congenital malformation of the male urogenital system. As a recently arisen reconstruction method for hypospadias, polymer tissue engineering urethral scaffold often results in necrosis and other complications due to the lack of bioactivity. To improve the bioactivity of polymer, in this work, we prepared biodegradable Mg/po...

Here, two novel approaches for disassembling epitaxial silicene from the native substrate and transferring onto arbitrary target substrates are presented. From the processing perspective, the two methodologies open up a new route for handling silicene, and in general any epitaxial Xene, in view of establishing reliable process flows for the develop...

Two-dimensional (2D) bismuth, bismuthene, is an emerging pnictogen family member that has received increasing research attention in the past few years, which could yield exotic electrical, thermal, and optical properties due to unique band structure. This review provides a holistic view of recent research advances on 2D bismuth material synthesis a...

The recent progress in sensing technology, energy devices, and wireless information technology continues to advance the new era of Internet of things (IoT). As it is associated with a variety of “things,” such as health monitors, smartphones, sensors, and power units, there are many research directions for IoT. By the end of this book, this chapter...

Two-dimensional (2D) layered materials hold great promise for various future electronic and optoelectronic devices that traditional semiconductors cannot afford. 2D pnictogen, group-VA atomic sheet (including phosphorene, arsenene, antimonene, and bismuthene) is believed to be a competitive candidate for next-generation logic devices. This is due t...

The fully-biodegradable composite rod with Mg-2Zn wires reinforced polylactic acid (PLA) for potential application in orthopedic internal fixation was prepared by hot-press method in this work. We performed different surface modifications on Mg-2Zn wires including micro-arc oxidation (MAO) and chemical conversion using dopamine (DA), hydrogen fluor...

Biodegradable composite rods with polylactic acid as matrix and Mg-2Zn wires as the reinforcement body were prepared by hot press and hot drawn method in this article. The main purpose is to improve the mechanical properties based on the strengthen and toughness effect of the directionally distributed Mg-2Zn wires in PLA matrix and the improved int...

Transparent and solution-processable nanoscale polyimide (NPI) films less than 100 nm thick and their applications as flexible gate dielectrics for 2D-materials-based transistor devices are reported. Stable electrical performances of NPI dielectric under high tensile strains up to 10% are demonstrated by in situ bending experiments. A welcome benef...

Besides theoretical studies, experimental investigations on silicene began with the synthesis of silicene on ceramic or metallic catalyst substrates such as ZrB2, Ir and Ag. Among various reported methods, the epitaxial growth of silicene sheet atop Ag(111) has received increasing attention and a derivative approach of using evaporated Ag(111) film...

Recently, two-dimensional (2D) atomic sheets have inspired new ideas in nanoscience including topologically-protected charge transport, spatially-separated excitons, and strongly anisotropic heat transport. Here, we report the intriguing observation of stable non-volatile resistance switching (NVRS) in single-layer atomic sheets sandwiched between...

Here, we report the intriguing observation of stable non-volatile resistance switching (NVRS) in single-layer atomic sheets sandwiched between metal electrodes. NVRS is observed in the prototypical semiconducting (MX2, M=Mo, W; and X=S, Se) transitional metal dichalcogenides (TMDs), and insulating hexagonal boron nitride (h-BN), which alludes to th...

We performed multiple-pass cold drawing for Mg-2wt%Zn alloy until 91% accumulative true strain, indicating an excellent drawing deformability of Mg alloy at room temperature. Based on texture analysis, the strong basal texture, which was formed during hot extrusion, was further strengthened at the initial stage of drawing. Subsequently, under the e...

Objectives As promising alternative to current metallic biomaterials, the porous Mg scaffold with a 3‐D open‐pore framework has drawn much attention in recent years due to its suitable biodegradation, biocompatibility, and mechanical properties for human bones. This experiment's aim is to study the mechanical properties, biosafety, and osteogenesis...

Tattoo-like epidermal sensors are an emerging class of truly wearable electronics owing to their thinness and softness. While most of them are based on thin metal films, silicon membrane, or nanoparticle-based printable inks, we report a sub-micron thick, multimodal electronic tattoo sensors that are made of graphene. The graphene electronic tattoo...

The structural and electronic properties of nanoscale Si epitaxially grown on Ag(111) can be tuned from a multilayer silicene phase, where the constitutive layers incorporate a mixed sp²/sp³ bonding, to other ordinary Si phases, such as amorphous and diamond-like Si. Based on comparative scanning tunneling microscopy and Raman spectroscopy investig...

Poly(methyl methacrylate) (PMMA) is commonly used as a temporary support layer for CVD graphene transfer; it is then removed by a chemical or thermal treatment. Regardless of the method used for PMMA removal, polymer residues are left on the graphene surface, which alter its intrinsic properties. A method based on isotope labeling of PMMA and time-...

We report the first direct dry transfer of a single-crystalline thin film grown by molecular beam epitaxy. A double cantilever beam fracture technique was used to transfer epitaxial bismuth thin films grown on silicon (111) to silicon strips coated with epoxy. The transferred bismuth films retained electrical, optical and structural properties comp...

Modern internet of things (IoTs) and ubiquitous sensor networks could potentially take advantage of chemically sensitive nanomaterials and nanostructures. However, their heterogeneous integration with other electronic modules on a networked sensor node, such as silicon-based modulators and memories, is inherently challenging because of compatibilit...

Here we present a very fast, selective mechanical approach for transferring graphene with low levels of copper contamination from seed wafers on which it was grown to target wafers for very large scale integration (VLSI) electronics. We found that graphene/copper or copper/silicon oxide delamination paths could be selected by slow and faster separa...

We report on employing molecular doping to enhance the sensitivity of graphenesensors synthesized via chemical vapor deposition to NH3 molecules at room temperature. We experimentally show that doping an as-fabricated graphenesensor with NO2 gas improves sensitivity of its electrical resistance to adsorption of NH3 molecules by about an order of ma...

We explored a support-free method for transferring large area chemical vapor deposition (CVD)-grown graphene films to various fluoric self-assembled monolayer (F-SAM) modified substrates including SiO2/Si wafers, polyethylene terephthalate (PET) films, and glass. This method yields clean, ultra-smooth and high-quality graphene films for promising a...

We report on our progress and development of high speed flexible graphene field effect transistors (GFETs) with high electron and hole mobilities (~3000 cm2/V·s), and intrinsic transit frequency in the microwave GHz regime. We also describe the design and fabrication of flexible graphene based radio frequency system. This RF communication system co...

Since its successful exfoliation and epitaxial growth in 2004 [1], [2], graphene, a honeycomb sp2 carbon lattice, has attracted interest because of its intrinsic high flexibility, electrical conductivity, and mobility. Among the various approaches to producing graphene, chemical vapor deposition (CVD) [3] is one of the most practical methods to sca...

Many of the attractive properties of graphene will only be realized when it can be mass produced. One bottleneck is the efficient transfer of graphene between various substrates in nanomanufacturing processes such as roll-to-roll and transfer printing. In such processes, it is important to understand how the ratio of shear-to-tension at the interfa...

[Invited] Nanoelectronics Based on Silicene In the past decade, two-dimensional (2D) materials have evolved into a big family with emerging new members beyond graphene, such as hexagonal boron nitride (hBN), transition metal dichalcogenides (TMDs), and elemental monolayers (e.g. silicene, phosphorene). Silicene, the group IV elemental cousin of gra...

High-mobility two-dimensional (2D) semiconductors are desirable for high-performance mechanically flexible nanoelectronics. In this work, we report the first flexible black phosphorus (BP) field-effect transistors (FETs) with electron and hole mobilities superior to what has been previously achieved with other more studied flexible layered semicond...

A very fast, dry transfer process based on mechanical delamination successfully effected the transfer of large-area, CVD grown graphene on copper foil to silicon. This has been achieved by bonding silicon backing layers to both sides of the graphene-coated copper foil with epoxy and applying a suitably high separation rate to the backing layers. At...

Thin metal films can be used to catalyze the growth of nanomaterials in place of the bulk metal, while greatly reducing the amount of material used. A big drawback of copper thin films (0.5-1.5 µm thick) is that under high temperature/vacuum synthesis, the mass loss of films severely reduces the process time due to discontinuities in the metal film...

In this work, hydrogen production from water is demonstrated via a p-type silicon photocathode with a thin epitaxial strontium titanate, SrTiO3 (STO), as capping layer by molecular beam epitaxy. The advantages of using STO are the ideal conduction band alignment and perfect lattice match between single crystalline SrTiO3 and Si, so the photogenerat...

Few-layer black phosphorus (BP), also known as phosphorene, is poised to be the most attractive graphene analogue owing to its high mobility approaching that of graphene, and its thickness- tunable band gap that can be as large as that of molybdenum disulfide. In essence, phosphorene represents the much sought after high-mobility, large direct band...

The largest applications of high-performance graphene will likely be realized when combined with ubiquitous Si very large scale integrated (VLSI) technology, affording a new portfolio of 'back end of the line' (BEOL) devices including graphene radio-frequency transistors, heat and transparent conductors, interconnects, mechanical actuators, sensors...

We report the enhancement of electrostatic transfer characteristics of fabricated graphene field-effect transistor (FET) by hexamethyldisilazane (HMDS) surface treatment. Charge carrier mobility increases by over 50% on average for both electron and hole. Impurity concentration also reduces by over 50% on average and charge neutrality point usually...

We report the improvement of the electrical characteristics of graphene field-effect transistors (FETs) by hexamethyldisilazane (HMDS) treatment. Both electron and hole field-effect mobilities are increased by 1.5 × –2×, accompanied by effective residual carrier concentration reduction. Dirac point also moves closer to zero Volt. Time evolution of...