Công bố mới năm 2019

09/03/2019 4:09 CH

A comprehensive review of flexible piezoelectirc generator based on organic-inorganic metal halide perovskites
Authors: Venkatraju Jella, Swathi Ippili, Ji-Ho Eom, S.V.N. Pammi, Hang-Soon Jung, Van-Dang Tran, Nguyen Van Hieu, Artavazd Kirakosyan, Deul Kim, Moon Ryul Sihn, Jihoon Choi, Yun-Jeong Kim, and Soon-Gil Yoon,
Journal: Nano Energy 57 (2019) 74-93. [Q1; ***IF2017: 13.61***]
Abstract: Organic-inorganic metal halide perovskites (OMHPs) have been extensively investigated over the past few years, not only because of their key features such as ease of solution-based processing, strong optical absorption, tunable bandgap, high carrier mobility, a long diffusion length, etc., and also because of their multi-faceted electronic applications with unprecedented power conversion efficiencies (PCE) in the field of photovoltaics. Apart from the impressive photovoltaic and optoelectronic applications, the applications for OMHPs have recently diverged towards mechanical energy harvesting applications owing to high levels of dielectric and piezoelectric properties that are relatively analogous to those of inorganic piezoelectric materials. Despite these assets, a fundamental understanding of physical behaviors such as ferroelectric and piezoelectric properties remains a key challenge that hampers the development of OMHP-based piezoelectric energy harvesters. This review updates the progress in nanogenerators for mechanical energy harvesting based on OMHPs and includes materials classifications and structural properties, as well as an overview of dielectric, ferroelectric, and piezoelectric properties based on the available literature. In addition, the numerous methods used to synthesize high-quality perovskite films and crystals are also addressed. In the overview of piezoelectric generators (PEGs), various approaches to PEGs based on OMHPs and flexible polymer composites are introduced. For flexible PEGs, fabrication, structural design, factors determining output, and applications are reviewed. Finally, some essential experimental features, perspectives, and issues in this exciting field are discussed and suggested.

Excellent detection of H2S gas at ppb concentration using ZnFe2O4 nanofibers loaded with reduced graphene oxide
Authors: Nguyen Van Hoang, Chu Manh Hung, Nguyen Duc Hoa, Nguyen Van Duy, Inkyu Park, Nguyen Van Hieu*
Journal: Sensors and Actuators B 282 (2019) 876-884. [Q1, ***IF2017: 5.66***]
Abstract: Cost-effective fabrication of sensors and detection of ultralow concentrations of toxic gases are important concerns for environmental monitoring. In this study, the reduced graphene oxide (RGO)-loaded ZnFe2O4 nanofibers (ZFO-NFs) were fabricated by facile on-chip electrospinning method and subsequent heat treatment. The multi-porous NFs with single-phase cubic spinel structure and typical spider-net morphology were directly assembled on Pt-interdigitated electrodes. The diameters of the RGO-loaded ZFO-NFs were approximately 50–100 nm with many nanograins. The responses to H2S gas showed a bell-shaped behaviour with respect to RGO contents and annealing temperatures. The optimal values of the RGO contents and the annealing temperatures were found to be about 1.0 wt% and 600 °C, respectively. The response of the RGO-loaded ZnFe2O4 NFs to 1 ppm H2S gas was as high as 147 at 350°C while their cross-gas responses to SO2 (10 ppm), NH3 (100 ppm), H2 (250 ppm), C3H6O (1000 ppm), and C2H5OH (1000 ppm) were rather low (1.8−5.6). The high sensor response was attributed to formation of a heterojunction between RGO and ZnFe2O4 and due to the fact that NFs consisted of many nanograins which resulted in multi-porous structure and formation of potential barriers at grain boundaries.

Magnetic iron oxide nanoparticles decorated graphene for gas sensing: The particle size effects
Authors: Tran Thanh Tung, Nguyen Viet Chien, Nguyen Van Duy, Nguyen Van Hieu*, J. Nine, C.J. Coghlan, Diana N.H. Tran, D. Losics*, "",
Journal: Journal of Colloid and Interface Science 539 (2019) 315-325. [Q1; ***IF2017: 5.09***].
Abstract: We report a synthesis of magnetic nanoparticles chemically immobilized onto reduced graphene oxide sheets (referred to as rGO-Fe3O4 NPs) as a gas and vapor sensing platform with precisely designed particle size of 5, 10 and 20 nm to explore their influence of particle size on sensing performance. The rGO-Fe3O4 NP sensors have been investigated their responses to different gases and volatile organic compounds (VOCs) at part-per-million (ppm) levels. Results show that the Fe3O4 NPs with smaller size (5 and 10 nm) on the rGO surface led to a lower sensitivity, while particles of a size of 20 nm have a significant enhancement of sensitivity compared to the bare rGO sensor. The rGO-Fe3O4 NP20 sensor can detect trace amounts of NO2 gas and ethanol vapor at the 1 ppm and is highly selective to the NO2 and ethanol among other tested gases and VOCs, respectively. The particle size causes different distribution behaviour of NPs over rGO surface and interspaced between them, which results in deceased or increased the surface interactions between gas and graphene. The NPs themselves contained different defects level and the charge depletion layer that affect their adsorption gas/vapor molecules, which are explained for different sensing responses.

An Eco-friendly flexible piezoelectric energy harverter that delivers high output performance is based on lead-free MASnI3Films and MASnI3-PVDF composite films
Authors: Swathi Ippili, Venkatraju Jella, Ji-Ho Eom, Jaegyu Kim, Seungbum Hong, Van-Dang Tran, Nguyen Van Hieu*, and Soon-Gil Yoon,
Journal: Nano Energy57 (2019) 911-923. [Q1;***IF2017: 13.61***]
Abstract: An environmentally-friendly lead-free methylammonium tin iodide (MASnI3) perovskite is successfully synthesized using a facile approach of an antisolvent-assisted collision technique (ACT) under room ambient conditions, which results stability within 24 h under ambient room conditions. The phase transition of MASnI3 from tetragonal to cubic is first observed at ~ 30°C. Polycrystalline MASnI3 films reveal a high dielectric constant of ~ 65 at 100 kHz, a low-leakage current density of 7 × 10−7 A cm−2 at 50 kV cm−1, well-developed P-E hysteresis loops, and a high piezoelectric coefficient (d33) of 20.8 pm V−1. The MASnI3 piezoelectric nanogenerator (PENG) shows an output voltage of ~ 3.8 V and an output current density of 0.35 μA cm−2. To enhance the piezoelectric output performance, the MASnI3 films are composited with an environmentally friendly PVDF polymer that had a porous structure. The PVDF-MASnI3 composite based-PENG reveals a maximum output voltage of ~ 12.0 V and current density of ~ 4.0 μA cm−2. A green light-emitting diode (LED) using the PVDF-MASnI3 PENGs is instantly lighted without need of a storage device, and long-term stability of the composite PENGs is validated for 90 days. This simple and cost-effective solution process is feasible for the fabrication of large-scale, high-performance, and environmental-friendly PENGs based on lead-free organic-inorganic perovskites to extensively implicate in medical and biomechanical applications.