Publications by authors named "Qijun Sun"

37 Publications

Fiber-Shaped Triboiontronic Electrochemical Transistor.

Research (Wash D C) 2021 26;2021:9840918. Epub 2021 Apr 26.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, China.

Contact electrification-activated triboelectric potential offers an efficient route to tuning the transport properties in semiconductor devices through electrolyte dielectrics, i.e., triboiontronics. Organic electrochemical transistors (OECTs) make more effective use of ion injection in the electrolyte dielectrics by changing the doping state of the semiconductor channel. However, the mainstream flexible/wearable electronics and OECT-based devices are usually modulated by electrical signals and constructed in conventional geometry, which lack direct and efficient interaction between the external environment and functional electronic devices. Here, we demonstrate a fiber-shaped triboiontronic electrochemical transistor with good electrical performances, including a current on/off ratio as high as ≈1286 with off-current at ~nA level, the average threshold displacements ( ) of 0.3 mm, the subthreshold swing corresponding to displacement (SS) at 1.6 mm/dec, and excellent flexibility and durability. The proposed triboiontronic electrochemical transistor has great potential to be used in flexible, functional, and smart self-powered electronic textile.
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http://dx.doi.org/10.34133/2021/9840918DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8098052PMC
April 2021

Hierarchical Architectures Based on Ru Nanoparticles/Oxygen-Rich-Carbon Nanotubes for Efficient Hydrogen Evolution.

Chemistry 2021 Aug 10;27(43):11150-11157. Epub 2021 Jun 10.

School of Chemical Engineering, College of Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 440-746, Republic of Korea.

Highly active and durable electrocatalysts are essential for producing hydrogen fuel through the hydrogen evolution reaction (HER). Here, a uniform deposition of Ru nanoparticles strongly interacting with oxygen-rich carbon nanotube architectures (Ru-OCNT) through ozonation and hydrothermal approaches has been designed. The hierarchical structure of Ru-OCNT is made by self-assembly of oxygen functionalities of OCNT. Ru nanoparticles interact strongly with OCNT at the Ru/OCNT interface to give excellent catalytic activity and stability of the Ru-OCNT, as further confirmed by density functional theory. Owing to the hierarchical structure and adjusted surface chemistry, Ru-OCNT has an overpotential of 34 mV at 10 mA cm with a Tafel slope of 27.8 mV dec in 1 M KOH, and an overpotential of 55 mV with Tafel slope of 33 mV dec in 0.5 M H SO . The smaller Tafel slope of Ru-OCNT than Ru-CNT and commercial Pt/C in both alkaline and acidic electrolytes indicates high catalytic activity and fast charge transfer kinetics. The as-proposed chemistry provides the rational design of hierarchically structured CNT/nanoparticle electrocatalysts for HER to produce hydrogen fuel.
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http://dx.doi.org/10.1002/chem.202101108DOI Listing
August 2021

Bioinspired mechano-photonic artificial synapse based on graphene/MoS heterostructure.

Sci Adv 2021 Mar 17;7(12). Epub 2021 Mar 17.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P. R. China.

Developing multifunctional and diversified artificial neural systems to integrate multimodal plasticity, memory, and supervised learning functions is an important task toward the emulation of neuromorphic computation. Here, we present a bioinspired mechano-photonic artificial synapse with synergistic mechanical and optical plasticity. The artificial synapse is composed of an optoelectronic transistor based on graphene/MoS heterostructure and an integrated triboelectric nanogenerator. By controlling the charge transfer/exchange in the heterostructure with triboelectric potential, the optoelectronic synaptic behaviors can be readily modulated, including postsynaptic photocurrents, persistent photoconductivity, and photosensitivity. The photonic synaptic plasticity is elaborately investigated under the synergistic effect of mechanical displacement and the light pulses embodying different spatiotemporal information. Furthermore, artificial neural networks are simulated to demonstrate the improved image recognition accuracy up to 92% assisted with mechanical plasticization. The mechano-photonic artificial synapse is highly promising for implementing mixed-modal interaction, emulating complex biological nervous system, and promoting the development of interactive artificial intelligence.
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http://dx.doi.org/10.1126/sciadv.abd9117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7968845PMC
March 2021

Contact-electrification-activated artificial afferents at femtojoule energy.

Nat Commun 2021 03 11;12(1):1581. Epub 2021 Mar 11.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, China.

Low power electronics endowed with artificial intelligence and biological afferent characters are beneficial to neuromorphic sensory network. Highly distributed synaptic sensory neurons are more readily driven by portable, distributed, and ubiquitous power sources. Here, we report a contact-electrification-activated artificial afferent at femtojoule energy. Upon the contact-electrification effect, the induced triboelectric signals activate the ion-gel-gated MoS postsynaptic transistor, endowing the artificial afferent with the adaptive capacity to carry out spatiotemporal recognition/sensation on external stimuli (e.g., displacements, pressures and touch patterns). The decay time of the synaptic device is in the range of sensory memory stage. The energy dissipation of the artificial afferents is significantly reduced to 11.9 fJ per spike. Furthermore, the artificial afferents are demonstrated to be capable of recognizing the spatiotemporal information of touch patterns. This work is of great significance for the construction of next-generation neuromorphic sensory network, self-powered biomimetic electronics and intelligent interactive equipment.
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http://dx.doi.org/10.1038/s41467-021-21890-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7952391PMC
March 2021

Paper-based triboelectric nanogenerators and their applications: a review.

Beilstein J Nanotechnol 2021 1;12:151-171. Epub 2021 Feb 1.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, P. R. China.

The development of industry and of the Internet of Things (IoTs) have brought energy issues and huge challenges to the environment. The emergence of triboelectric nanogenerators (TENGs) has attracted wide attention due to their advantages, such as self-powering, lightweight, and facile fabrication. Similarly to paper and other fiber-based materials, which are biocompatible, biodegradable, environmentally friendly, and are everywhere in daily life, paper-based TENGs (P-TENGs) have shown great potential for various energy harvesting and interactive applications. Here, a detailed summary of P-TENGs with two-dimensional patterns and three-dimensional structures is reported. P-TENGs have the potential to be used in many practical applications, including self-powered sensing devices, human-machine interaction, electrochemistry, and highly efficient energy harvesting devices. This leads to a simple yet effective way for the next generation of energy devices and paper electronics.
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http://dx.doi.org/10.3762/bjnano.12.12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7871030PMC
February 2021

Multifunctional Coaxial Energy Fiber toward Energy Harvesting, Storage, and Utilization.

ACS Nano 2021 Jan 11;15(1):1597-1607. Epub 2021 Jan 11.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China.

Fibrous energy-autonomy electronics are highly desired for wearable soft electronics, human-machine interfaces, and the Internet of Things. How to effectively integrate various functional energy fibers into them and realize versatile applications is an urgent need to be fulfilled. Here, a multifunctional coaxial energy fiber has been developed toward energy harvesting, energy storage, and energy utilization. The energy fiber is composed of an all fiber-shaped triboelectric nanogenerator (TENG), supercapacitor (SC), and pressure sensor in a coaxial geometry. The inner core is a fibrous SC by a green activation strategy for energy storage; the outer sheath is a fibrous TENG in single-electrode mode for energy harvesting, and the outer friction layer and inner layer (covered with Ag) constitute a self-powered pressure sensor. The electrical performances of each energy component are systematically investigated. The fibrous SC shows a length specific capacitance density of 13.42 mF·cm, good charging/discharging rate capability, and excellent cycling stability (∼96.6% retention). The fibrous TENG shows a maximum power of 2.5 μW to power an electronic watch and temperature sensor. The pressure sensor has a good enough sensitivity of 1.003 V·kPa to readily monitor the real-time finger motions and work as a tactile interface. The demonstrated energy fibers have exhibited stable electrochemical and mechanical performances under mechanical deformation, which make them attractive for wearable electronics. The demonstrated soft and multifunctional coaxial energy fiber is also of great significance in a sustainable human-machine interactive system, intelligent robotic skin, security tactile switches,
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http://dx.doi.org/10.1021/acsnano.0c09146DOI Listing
January 2021

Atomic threshold-switching enabled MoS transistors towards ultralow-power electronics.

Nat Commun 2020 Dec 4;11(1):6207. Epub 2020 Dec 4.

Institute of Microelectronics, Beijing Innovation Center for Future Chips (ICFC), Tsinghua University, 100084, Beijing, China.

Power dissipation is a fundamental issue for future chip-based electronics. As promising channel materials, two-dimensional semiconductors show excellent capabilities of scaling dimensions and reducing off-state currents. However, field-effect transistors based on two-dimensional materials are still confronted with the fundamental thermionic limitation of the subthreshold swing of 60 mV decade at room temperature. Here, we present an atomic threshold-switching field-effect transistor constructed by integrating a metal filamentary threshold switch with a two-dimensional MoS channel, and obtain abrupt steepness in the turn-on characteristics and 4.5 mV decade subthreshold swing (over five decades). This is achieved by using the negative differential resistance effect from the threshold switch to induce an internal voltage amplification across the MoS channel. Notably, in such devices, the simultaneous achievement of efficient electrostatics, very small sub-thermionic subthreshold swings, and ultralow leakage currents, would be highly desirable for next-generation energy-efficient integrated circuits and ultralow-power applications.
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http://dx.doi.org/10.1038/s41467-020-20051-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7719160PMC
December 2020

Benign Integration of a Zn-Azolate Metal-Organic Framework onto Textile Fiber for Ammonia Capture.

ACS Appl Mater Interfaces 2020 Oct 8;12(42):47747-47753. Epub 2020 Oct 8.

Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.

Ammonia (NH) exposure has a serious impact on human health because of its toxic and corrosive nature. Therefore, efficient personal protective equipment (PPE) such as masks is necessary to eliminate and mitigate NH exposure risks. Because economically and environmentally viable conditions are of interest for large-scale manufacture of PPE, we herein report a benign procedure to synthesize a Zn-azolate metal-organic framework (MOF), MFU-4, for NH capture. The surface area and morphology of MFU-4 obtained in alcohol solvents at room temperature is consistent with that of traditionally synthesized MFU-4 in ,-dimethylformamide at 140 °C. In addition to its large NH uptake capacity at 1 bar (17.7 mmol/g), MFU-4 shows outstanding performance in capturing NH at low concentration (10.8 mmol/g at 0.05 bar). Furthermore, the mild synthetic conditions implemented make it facile to immobilize MFU-4 onto cotton textile fiber. Enhanced NH capture ability of the MFU-4/fiber composite was also attributed to the well-exposed MOF particles. The benign synthetic MFU-4 procedure, high NH uptake, and easy integration onto fiber pave the way toward implementation of similar materials in PPE.
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http://dx.doi.org/10.1021/acsami.0c14316DOI Listing
October 2020

Highly Stable Vanadium Redox-Flow Battery Assisted by Redox-Mediated Catalysis.

Small 2020 Sep 18;16(38):e2003321. Epub 2020 Aug 18.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China.

With good operation flexibility and scalability, vanadium redox-flow batteries (VRBs) stand out from various electrochemical energy storage (EES) technologies. However, traditional electrodes in VRBs, such as carbon and graphite felt with low electrochemical activities, impede the interfacial charge transfer processes and generate considerable overpotential loss, which significantly decrease the energy and voltage efficiencies of VRBs. Herein, by using a facile electrodeposition technique, Prussian blue/carbon felt (PB/CF) composite electrodes with high electrochemical activity for VRBs are successfully fabricated. The PB/CF electrode exhibits excellent electrochemical activity toward VO /VO redox couple in VRB with an average cell voltage efficiency (VE) of 90% and an energy efficiency (EE) of 88% at 100 mA cm . In addition, due to the uniformly distributed PB particles that are strongly bound to the surface of carbon fibers in CF, VRBs with the PB/CF electrodes show much better long-term stabilities compared with the pristine CF-based battery due to the redox-mediated catalysis. A VRB stack consisting of three single cells (16 cm ) is also constructed to assess the reliability of the redox-mediated PB/CF electrodes for large-scale application. The facile technique for the high-performance electrode with redox-mediated reaction is expected to shed new light on commercial electrode design for VRBs.
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http://dx.doi.org/10.1002/smll.202003321DOI Listing
September 2020

Versatile Triboiontronic Transistor Proton Conductor.

ACS Nano 2020 Jul 25;14(7):8668-8677. Epub 2020 Jun 25.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China.

Iontronics are effective in modulating electrical properties through the electric double layers (EDLs) assisted with ionic migration/arrangement, which are highly promising for unconventional electronics, ionic sensory devices, and flexible interactive interface. Proton conductors with the smallest and most abundant protons (H) can realize a faster migration/polarization under electric field to form the EDL with higher capacitance. Here, a versatile triboiontronic MoS transistor proton conductor by sophisticated combination of triboelectric modulation and protons migration has been demonstrated. This device utilizes triboelectric potential originated from mechanical displacement to modulate the electrical properties of transistors protons migration/accumulation. It shows superior electrical properties, including high current on/off ratio over 10, low cutoff current (∼0.04 pA), and steep switching properties (89 μm/dec). Pioneering noise tests are conducted to the tribotronic devices to exclude the possible noise interference introduced by mechanical displacement. The versatile triboiontronic MoS transistor proton conductor has been utilized for mechanical behavior derived logic devices and an artificial sensory neuron system. This work represents the reliable and effective triboelectric potential modulation on electronic transportation through protonic dielectrics, which is highly desired for theoretical study of tribotronic gating, active mechanosensation, self-powered electronic skin, artificial intelligence, .
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http://dx.doi.org/10.1021/acsnano.0c03030DOI Listing
July 2020

Facile Synthesis of Phosphorus and Cobalt Co-Doped Graphitic Carbon Nitride for Fire and Smoke Suppressions of Polylactide Composite.

Polymers (Basel) 2020 May 12;12(5). Epub 2020 May 12.

Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR 999077, China.

Due to the unique two-dimensional structure and features of graphitic carbon nitride (g-CN), such as high thermal stability and superior catalytic property, it is considered to be a promising flame retardant nano-additive for polymers. Here, we reported a facile strategy to prepare cobalt/phosphorus co-doped graphitic carbon nitride (Co/P-CN) by a simple and scalable thermal decomposition method. The structure of Co/P-CN was confirmed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The carbon atoms in g-CN were most likely substituted by phosphorous atoms. The thermal stability of polylactide (PLA) composites was increased continuously with increasing the content of Co/P-CN. In contrast to the g-CN, the Polylactide (PLA) composites containing Co/P-CN exhibited better flame retardant efficiency and smoke suppression. With the addition of 10 wt % Co/P-CN, the peak heat release rate (PHRR), carbon dioxide (CO) production (PCO2P) and carbon oxide (CO) production (PCOP) values of PLA composites decreased by 22.4%, 16.2%, and 38.5%, respectively, compared to those of pure PLA, although the tensile strength of PLA composites had a slightly decrease. The char residues of Co/P-CN composites had a more compact and continuous structure with few cracks. These improvements are ascribed to the physical barrier effect, as well as catalytic effects of Co/P-CN, which inhibit the rapid release of combustible gaseous products and suppression of toxic gases, i.e., CO.
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http://dx.doi.org/10.3390/polym12051106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285335PMC
May 2020

A Cost-effective Nafion Composite Membrane as an Effective Vanadium-Ion Barrier for Vanadium Redox Flow Batteries.

Chem Asian J 2020 Aug 2;15(15):2357-2363. Epub 2020 Apr 2.

College of Materials Science and Engineering, Changsha University of Science & Technology, Changsha, 410114, P. R. China.

Ion exchange membranes play a key role in all vanadium redox flow batteries (VRFBs). The mostly available commercial membrane for VRFBs is Nafion. However, its disadvantages, such as high cost and severe vanadium-ion permeation, become obstacles for large-scale energy storage. It is thus crucial to develop an efficient membrane with low permeability of vanadium ions and low cost to promote commercial applications of VRFBs. In this study, graphene oxide (GO) has been employed as an additive to the Nafion 212 matrix and a composite membrane named rN212/GO obtained. The thickness of rN212/GO has been reduced to only 41 μm (compared with 50 μm Nafion 212), which indicates directly lower cost. Meanwhile, rN212/GO shows lower permeability of vanadium ions and area-specific resistance compared to the Nafion 212 membrane due to the abundant oxygen-containing functional groups of GO additives. The VRFB cells with the rN212/GO membrane show higher Coulombic efficiencies and lower capacity decay than those of VRFB cells with the Nafion 212 membrane. Therefore, the cost-effective rN212/GO composite membrane is a promising alternative to suppress migration of vanadium ions across the membrane to set up VRFB cells with better performances.
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http://dx.doi.org/10.1002/asia.202000140DOI Listing
August 2020

Ion Gel Capacitively Coupled Tribotronic Gating for Multiparameter Distance Sensing.

ACS Nano 2020 Mar 20;14(3):3461-3468. Epub 2020 Feb 20.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China.

Developing sophisticated device architectures is of great significance to go beyond Moore's law with versatility toward human-machine interaction and artificial intelligence. Tribotronics/tribo-iontronics offer a direct way to controlling the transport properties of semiconductor devices by mechanical actions, which fundamentally relies on how to enhance the tribotronic gating effect through device engineering. Here, we propose a universal method to enhance the tribotronic properties through electric double layer (EDL) capacitive coupling. By preparing an ion gel layer on top of tribotronic graphene transistor, we demonstrate a dual-mode field effect transistor (, a tribotronic transistor with capacitively coupled ion gel and an ion-gel-gated graphene transistor with a second tribotronic gate). The resulted tribotronic gating performances are greatly improved by twice for the on-state current and four times for the on/off ratio (the first mode). It can also be utilized as a multiparameter distance sensor with drain current increased by ∼600 μA and threshold voltage shifted by ∼0.8 V under a mechanical displacement of 0.25 mm (the second mode). The proposed methodology of EDL capacitive coupling offers a facile and efficient way to designing more sophisticated tribotronic devices with superior performance and multifunctional sensations.
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http://dx.doi.org/10.1021/acsnano.9b09549DOI Listing
March 2020

A Allele of Rs5498 and Rs3181092 is Correlated with Increased Risk for Periodontal Disease.

Open Life Sci 2019 Jan 31;14:638-646. Epub 2019 Dec 31.

Stomatology Therapeutic Center, Huzhou Central Hospital, Affiliated Cent Hosp Huzhou University, Huzhou 313000, P.R. China.

Objective: Periodontal disease (PD) is viewed today as multifactorial problems initiated and sustained by bacteria but significantly modified by the body's response to bacterial plaque. Recent studies have suggested that gene polymorphisms could be involved in the pathophysiology of periodontitis. This study aimed to investigate a possible correlation of the polymorphisms of intercellular adhesion molecule-1 () and vascular cell adhesion molecule-1 () with PD.

Methods: The genotypes of and were initially determined in PD patients using denaturing high performance liquid chromatography (DHPLC). ELISA was then conducted to measure and protein levels. Next, the association of genotype distribution and expression with clinical indicators and severity of PD was analyzed.

Results: PD patients contained increased levels of hemoglobin A1c (HbA1c), total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL), increased and protein levels, and decreased high-density lipoprotein (HDL) level. The GG genotype and G allele at rs5498, as well as the AG and GG genotypes and G allele at rs3181092 may reduce PD risk.

Conclusion: To sum up, the overexpressed and as well as A allele of rs5498 and rs3181092 is associated with the onset of PD.
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http://dx.doi.org/10.1515/biol-2019-0072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7874761PMC
January 2019

Textile carbon network with enhanced areal capacitance prepared by chemical activation of cotton cloth.

J Colloid Interface Sci 2019 Oct 17;553:705-712. Epub 2019 Jun 17.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China; School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China; Center on Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning 530004, China. Electronic address:

Flexible all-solid-state supercapacitors are emerging as one of the most gratifying energy storage devices in the application of portable and wearable electronics. The design and fabrication of high-performance and flexible electrodes are crucial for an all-solid-state supercapacitor. Herein we report a free-standing textile carbon network composed of activated textile carbon (aTC) by thermal annealing of cotton cloth, followed by chemical activation with KOH. The aTC fibers remain the unique features of surface wrinkles and hollow tubular structure of the natural cotton fibers, together with the abundant micropores introduced by further chemical activation, making the specific surface area of the aTC-3 fibers reach 1075 m g with a high electrical conductivity of 1506 S m. When served as the supercapacitor electrode, the aTC-3 exhibits a specific capacitance as high as 1026 mF cm with a capacitance retention of 85% at 100 mA cm (868 mF cm), which is far superior to commercial carbon cloth. More interestingly, the long-range continuous structure enables aTC as electrode of solid-state supercapacitor, which delivers an outstanding mechanical flexibility without noticeable change of capacitive performance when folded at maximal angle of 180° over 200 cycles. This work may benefit the low-cost mass production of carbon-based flexible electrodes for developing wearable electrochemical energy storage systems.
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http://dx.doi.org/10.1016/j.jcis.2019.06.048DOI Listing
October 2019

Fabrication of carboxymethyl cellulose and graphene oxide bio-nanocomposites for flexible nonvolatile resistive switching memory devices.

Carbohydr Polym 2019 Jun 14;214:213-220. Epub 2019 Mar 14.

Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China. Electronic address:

Nowadays the development of natural biomaterials as promising building polymers for flexible, biodegradable, biocompatible and environmentally friendly electronic devices is of great interest. As the most common natural polymers, cellulose and its derivatives have the potential to be applied in the devices owing to the easy processing, nontoxicity and biodegradability. Here, write-once-read-many-times resistive switching devices based on biodegradable carboxymethyl cellulose-graphene oxide (CMC-GO) nanocomposite are demonstrated for the first time. The hybridization sites formed by the gelation of CMC and GO molecules contribute to the excellent memory behaviors. When compared with devices base on pure GO and CMC, the device with the Al/CMC-GO/Al/SiO structure exhibits brilliant write-once-read-many-times (WORM) switching characteristics such as high ON/OFF current ratio of ˜10, low switching voltage of 2.22 V, excellent stability and durability. What's more, the device shows high flexibility and good resistive switching behaviors even with soft PET substrate (Al/CMC-GO/Al/PET structure). This newly designed cellulose-graphene oxide-based polymer nanocomposites are quite cheap and easy processed for large scale manufacturing of memory devices and can further contribute to future biodegradable data storage applications such as portable stretchable displays, wearable electronics and electronic skins in the coming age of artificial intelligence.
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http://dx.doi.org/10.1016/j.carbpol.2019.03.040DOI Listing
June 2019

Ecofriendly UV-protective films based on poly(propylene carbonate) biocomposites filled with TiO decorated lignin.

Int J Biol Macromol 2019 Apr 3;126:1030-1036. Epub 2019 Jan 3.

Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China. Electronic address:

It is highly desirable to develop biodegradable UV-shielding materials from the renewable resources as the ever-increasing demand for the sustainable environment. In this work, TiO decorated lignin particles ([email protected]) were synthesized successfully by hydrothermal method in aqueous solution to improve the UV shielding performance of lignin particles. The poly(propylene carbonate) (PPC) composite films (thickness of ~23 μm) with different contents of [email protected] were prepared via a blade-casting method. Morphological analysis showed that the [email protected] dispersed uniformly in the PPC matrix with a good miscibility. UV-vis transmission spectra results revealed that the PPC composite film containing 5 wt% [email protected] could absorb about 90% of UV light in the full UV band (200-400 nm), indicating the [email protected] had a good UV-shielding property. Moreover, the presence of [email protected] could significantly improve the thermal stability of the PPC/[email protected] composite films. The DMA results showed that the introduction of [email protected] could enhance the storage modulus and glass transition temperature simultaneously.
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http://dx.doi.org/10.1016/j.ijbiomac.2018.12.273DOI Listing
April 2019

Triboiontronic Transistor of MoS.

Adv Mater 2019 Feb 27;31(7):e1806905. Epub 2018 Dec 27.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, P. R. China.

Electric double layers (EDLs) formed in electrolyte-gated field-effect transistors (FETs) induce an extremely large local electric field that gives a highly efficient charge carrier control in the semiconductor channel. To achieve highly efficient triboelectric potential gating on the FET and explore diversified applications of electric double layer FETs (EDL-FETs), a triboiontronic transistor is proposed to bridge triboelectric potential modulation and ion-controlled semiconductor devices. Utilizing the triboelectric potential instead of applying an external gate voltage, the triboiontronic MoS transistor is efficiently operated owing to the formation of EDLs in the ion-gel dielectric layer. The operation mechanism of the triboiontronic transistor is proposed, and high current on/off ratio over 10 , low threshold value (75 μm), and steep switching properties (20 µm dec ) are achieved. A triboiontronic logic inverter with desirable gain (8.3 V mm ), low power consumption, and high stability is also demonstrated. This work presents a low-power-consuming, active, and a general approach to efficiently modulate semiconductor devices through mechanical instructions, which has great potential in human-machine interaction, electronic skin, and intelligent wearable devices. The proposed triboiontronics utilize ion migration and arrangement triggered by mechanical stimuli to control electronic properties, which are ready to deliver new interdisciplinary research directions.
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http://dx.doi.org/10.1002/adma.201806905DOI Listing
February 2019

Static and Dynamic Piezopotential Modulation in Piezo-Electret Gated MoS Field-Effect Transistor.

ACS Nano 2019 Jan 19;13(1):582-590. Epub 2018 Dec 19.

Beijing Institute of Nanoenergy and Nanosystems , Chinese Academy of Sciences , Beijing 100083 , China.

The piezotronic effect links the mechanical stimuli with various semiconductor devices, promising for low-power-consuming electronic devices, sensitive sensors, and interactive control systems. The persistent requirement for external strains in piezotronic modulation may hinder its application in some circumstances (such as devices on rigid substrate or complicated synergistic piezoelectric modulation on multidevice). Here, we propose an efficient method to realize piezoelectric modulation of optical and electrical properties of MoS FET in both static and dynamic manner, expanding the application of piezotronics. Through capacitive coupling between piezo-electret and MoS FET, the remanent piezo-potential can efficiently tune the Fermi level of MoS, programming the initial electrical property for subsequent fabrication of sophisticated devices. The external strain can induce enhanced piezo-potentials to further affect the energy band bending of MoS channel, giving rise to high-performance strain sensors (large gauge factor ∼4800, fast response time ∼0.15 s, and good durability >1000 s). The proposed static and dynamic piezopotential tuned MoS FET is easy to extend to devices based on other materials, which is highly desired in tunable sensory systems, active flexible electronics, and human-machine interface.
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http://dx.doi.org/10.1021/acsnano.8b07477DOI Listing
January 2019

Mechanosensation-Active Matrix Based on Direct-Contact Tribotronic Planar Graphene Transistor Array.

ACS Nano 2018 09 7;12(9):9381-9389. Epub 2018 Sep 7.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences , Beijing 100083 , China.

Mechanosensitive electronics aims at replicating the multifunctions of human skin to realize quantitative conversion of external stimuli into electronic signals and provide corresponding feedback instructions. Here, we report a mechanosensation-active matrix based on a direct-contact tribotronic planar graphene transistor array. Ion gel is utilized as both the dielectric in the graphene transistor and the friction layer for triboelectric potential coupling to achieve highly efficient gating and sensation properties. Different contact distances between the ion gel and other friction materials produce different triboelectric potentials, which are directly coupled to the graphene channel and lead to different output signals through modulating the Fermi level of graphene. Based on this mechanism, the tribotronic graphene transistor is capable of sensing approaching distances, recognizing the category of different materials, and even distinguishing voices. It possesses excellent sensing properties, including high sensitivity (0.16 mm), fast response time (∼15 ms), and excellent durability (over 1000 cycles). Furthermore, the fabricated mechanosensation-active matrix is demonstrated to sense spatial contact distances and visualize a 2D color mapping of the target object. The tribotronic active matrix with ion gel as dielectric/friction layer provides a route for efficient and low-power-consuming mechanosensation in a noninvasive fashion. It is of great significance in multifunction sensory systems, wearable human-machine interactive interfaces, artificial electronic skin, and future telemedicine for patient surveillance.
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http://dx.doi.org/10.1021/acsnano.8b04490DOI Listing
September 2018

Rhelogical and antibacterial performance of sodium alginate/zinc oxide composite coating for cellulosic paper.

Colloids Surf B Biointerfaces 2018 Jul 1;167:538-543. Epub 2018 May 1.

Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong. Electronic address:

Coating of antibacterial layer on the surface of cellulosic paper has numerous potential applications. In the present work, sodium alginate (SA) served as a binder to disperse Zn and the prepared zinc oxide (ZnO) particles were used as antibacterial agents. The rheology test revealed that there were cross-linking between Zn and SA molecular chains in the aqueous solution, resulting in the viscosity of ZnO/SA composite coating increased in the low shear rate region and decreased in the high shear rate region as compared with pure SA. SEM and EDS mapping images showed that the ZnO particles were prepared successfully at 120 °C and dispersed homogeneously on the surface of cellulose fibers and the pores of cellulosic papers. The thermal stabilities of the coated papers decreased as compared to the original blank cellulosic paper, which was ascribed to the low thermal stability of SA and the catalytic effect of ZnO on SA. The tensile stress and Young's modulus of ZnO/SA composite coated paper increased up 39.5% and 30.7%, respectively, as compared with those of blank cellulosic paper. The antibacterial activity tests indicated that the ZnO/SA composite coating endowed the cellulosic paper with effectively growth inhibition of both Gram-negative bacteria E. coli and Gram-positive bacteria S. aureu.
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http://dx.doi.org/10.1016/j.colsurfb.2018.04.058DOI Listing
July 2018

Tunable Tribotronic Dual-Gate Logic Devices Based on 2D MoS and Black Phosphorus.

Adv Mater 2018 Mar 13;30(13):e1705088. Epub 2018 Feb 13.

CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, China.

With the Moore's law hitting the bottleneck of scaling-down in size (below 10 nm), personalized and multifunctional electronics with an integration of 2D materials and self-powering technology emerge as a new direction of scientific research. Here, a tunable tribotronic dual-gate logic device based on a MoS field-effect transistor (FET), a black phosphorus FET and a sliding mode triboelectric nanogenerator (TENG) is reported. The triboelectric potential produced from the TENG can efficiently drive the transistors and logic devices without applying gate voltages. High performance tribotronic transistors are achieved with on/off ratio exceeding 106 and cutoff current below 1 pA μm . Tunable electrical behaviors of the logic device are also realized, including tunable gains (improved to ≈13.8) and power consumptions (≈1 nW). This work offers an active, low-power-consuming, and universal approach to modulate semiconductor devices and logic circuits based on 2D materials with TENG, which can be used in microelectromechanical systems, human-machine interfacing, data processing and transmission.
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http://dx.doi.org/10.1002/adma.201705088DOI Listing
March 2018

Interface Engineering via Photopolymerization-Induced Phase Separation for Flexible UV-Responsive Phototransistors.

ACS Appl Mater Interfaces 2018 Feb 20;10(8):7487-7496. Epub 2018 Feb 20.

Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology , Wuhan 430074, China.

Interface engineering has been recognized to be substantially critical for achieving efficient charge separation, charge carrier transport, and enhanced device performance in emerging optoelectronics. Nevertheless, precise control of the interface structure using current techniques remains a formidable challenge. Herein, we demonstrate a facile and versatile protocol wherein in situ thiol-ene click photopolymerization-induced phase separation is implemented for constructing heterojunction semiconductor interfaces. This approach generates continuous mountainlike heterojunction interfaces that favor efficient exciton dissociation at the interface while providing a continuous conductive area for hole transport above the interface. This facile low-temperature paradigm presents good adaptability to both rigid and flexible substrates, offering high-performance UV-responsive phototransistors with a normalized detectivity up to 6.3 × 10 cm Hz W (also called jones). Control experiments based on ex situ photopolymerization and in situ thermal polymerization are also implemented to demonstrate the superiority of this novel paradigm.
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http://dx.doi.org/10.1021/acsami.7b19371DOI Listing
February 2018

Transparent and Self-Powered Multistage Sensation Matrix for Mechanosensation Application.

ACS Nano 2018 01 22;12(1):254-262. Epub 2017 Dec 22.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences , Beijing 100083, China.

Electronic skin based on a multimodal sensing array is ready to detect various stimuli in different categories by utilizing highly sensitive materials, sophisticated geometry designs, and integration of multifunctional sensors. However, it is still difficult to distinguish multiple and complex mechanical stimuli in a local position by conventional multimodal E-skin, which is significantly important in the signals' feedback of robotic fine motions and human-machine interactions. Here, we present a transparent, flexible, and self-powered multistage sensation matrix based on piezoelectric nanogenerators constructed in a crossbar design. Each sensor cell in the matrix comprises a layer of piezoelectric polymer sandwiched between two graphene electrodes. The simple lamination design allows sequential multistage sensation in one sensing cell, including compressive/tensile strain and detaching/releasing area. Further structure engineering on PDMS substrate allows the sensor cell to be highly sensitive to the applied pressures, representing the minimum sensing pressure below 800 Pa. As the basic combinations of compressive/tensile strains or detaching/releasing represent individual output signals, the proposed multistage sensors are capable of decoding to distinguish external complex motions. The proposed self-powering multistage sensation matrix can be used universally as an autonomous invisible sensory system to detect complex motions of the human body in local position, which has promising potential in movement monitoring, human-computer interaction, humanoid robots, and E-skins.
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http://dx.doi.org/10.1021/acsnano.7b06126DOI Listing
January 2018

Crack-Enhanced Microfluidic Stretchable E-Skin Sensor.

ACS Appl Mater Interfaces 2017 Dec 14;9(51):44678-44686. Epub 2017 Dec 14.

Interaction Lab, ATRC, Korea University of Technology and Education , Cheonan 31253, Republic of Korea.

We reported the development of a transparent stretchable crack-enhanced microfluidic capacitive sensor array for use in E-skin applications. The microfluidic sensor was fabricated through a simple lamination process involving two silver nanowire (AgNW)-embedded rubbery microfluidic channels arranged in a crisscross fashion. The sensing performance was optimized by testing a variety of sensing liquids injected into the channels. External mechanical stimuli applied to the sensor induced the liquid to penetrate the deformed microcracks on the rubber channel surface. The increased interfacial contact area between the liquid and the nanowire electrodes increased the capacitance of the sensor. The device sensitivity was strongly related to both the initial fluid interface between the liquid and crack wall and the change in the contact length of the liquid and crack wall, which were simulated using the finite element method. The microfluidic sensor was shown to detect a wide range of pressures, 0.1-140 kPa. Ordinary human motions, including substantial as well as slight muscle movements, could be successively detected, and 2D color mappings of simultaneous external load sensing were collected. Our simple method of fabricating the microfluidic channels and the application of these channels to stretchable e-skin sensors offers an excellent sensing platform that is highly compatible with emerging medical and electronic applications.
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http://dx.doi.org/10.1021/acsami.7b15999DOI Listing
December 2017

Highly Sensitive MoS Humidity Sensors Array for Noncontact Sensation.

Adv Mater 2017 Sep 10;29(34). Epub 2017 Jul 10.

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.

Recently, 2D materials exhibit great potential for humidity sensing applications due to the fact that almost all atoms are at the surface. Therefore, the quality of the material surface becomes the key point for sensitive perception. This study reports an integrated, highly sensitive humidity sensors array based on large-area, uniform single-layer molybdenum disulfide with an ultraclean surface. Device mobilities and on/off ratios decrease linearly with the relative humidity varying from 0% to 35%, leading to a high sensitivity of more than 10 . The reversible water physisorption process leads to short response and decay times. In addition, the device array on a flexible substrate shows stable performance, suggesting great potential in future noncontact interface localization applications.
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http://dx.doi.org/10.1002/adma.201702076DOI Listing
September 2017

An Overview of the Development of Flexible Sensors.

Adv Mater 2017 Sep 3;29(33). Epub 2017 Jul 3.

Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR.

Flexible sensors that efficiently detect various stimuli relevant to specific environmental or biological species have been extensively studied due to their great potential for the Internet of Things and wearable electronics applications. The application of flexible and stretchable electronics to device-engineering technologies has enabled the fabrication of slender, lightweight, stretchable, and foldable sensors. Here, recent studies on flexible sensors for biological analytes, ions, light, and pH are outlined. In addition, contemporary studies on device structure, materials, and fabrication methods for flexible sensors are discussed, and a market overview is provided. The conclusion presents challenges and perspectives in this field.
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http://dx.doi.org/10.1002/adma.201700375DOI Listing
September 2017

Piezopotential-Programmed Multilevel Nonvolatile Memory As Triggered by Mechanical Stimuli.

ACS Nano 2016 12 9;10(12):11037-11043. Epub 2016 Dec 9.

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, National Center for Nanoscience and Nanotechnology (NCNST), Beijing 100083, P. R. China.

We report the development of a piezopotential-programmed nonvolatile memory array using a combination of ion gel-gated field-effect transistors (FETs) and piezoelectric nanogenerators (NGs). Piezopotentials produced from the NGs under external strains were able to replace the gate voltage inputs associated with the programming/erasing operation of the memory, which reduced the power consumption compared with conventional memory devices. Multilevel data storage in the memory device could be achieved by varying the external bending strain applied to the piezoelectric NGs. The resulting devices exhibited good memory performance, including a large programming/erasing current ratio that exceeded 10, multilevel data storage of 2 bits (over 4 levels), performance stability over 100 cycles, and stable data retention over 3000 s. The piezopotential-programmed multilevel nonvolatile memory device described here is important for applications in data-storable electronic skin and advanced human-robot interface operations.
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http://dx.doi.org/10.1021/acsnano.6b05895DOI Listing
December 2016

Wafer-Scale Microwire Transistor Array Fabricated via Evaporative Assembly.

ACS Appl Mater Interfaces 2016 Jun 7;8(24):15543-50. Epub 2016 Jun 7.

Department of Polymer Science and Engineering, Kyungpook National University , Daegu 41566, Korea.

One-dimensional (1D) nano/microwires have attracted significant attention as promising building blocks for various electronic and optical device applications. The integration of these elements into functional device networks with controlled alignment and density presents a significant challenge for practical device applications. Here, we demonstrated the fabrication of wafer-scale microwire field-effect transistor (FET) arrays based on well-aligned inorganic semiconductor microwires (indium-gallium-zinc-oxide (IGZO)) and organic polymeric insulator microwires fabricated via a simple and large-area evaporative assembly technique. This microwire fabrication method offers a facile approach to precisely manipulating the channel dimensions of the FETs. The resulting solution-processed monolithic IGZO microwire FETs exhibited a maximum electron mobility of 1.02 cm(2) V(-1) s(-1) and an on/off current ratio of 1 × 10(6). The appropriate choice of the polymeric microwires used to define the channel lengths enabled fine control over the threshold voltages of the devices, which were employed to fabricate high-performance depletion-load inverters. Low-voltage-operated microwire FETs were successfully fabricated on a plastic substrate using a high-capacitance ion gel gate dielectric. The microwire fabrication technique involving evaporative assembly provided a facile, effective, and reliable method for preparing flexible large-area electronics.
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http://dx.doi.org/10.1021/acsami.6b04340DOI Listing
June 2016

Stretchable and Multimodal All Graphene Electronic Skin.

Adv Mater 2016 04 2;28(13):2601-8. Epub 2016 Feb 2.

SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, South Korea.

A transparent and stretchable all-graphene multifunctional electronic-skin sensor matrix is developed. Three different functional sensors are included in this matrix: humidity, thermal, and pressure sensors. These are judiciously integrated into a layer-by-layer geometry through a simple lamination process.
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http://dx.doi.org/10.1002/adma.201505739DOI Listing
April 2016
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