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Effect of composition on the ability to form SiC/SiO2-C composite from rice husk and silica gel
Do Quang Minh,Tran Van Khai,Huynh Ngoc Minh,Nguyen Vu Uyen Nhi,Kieu Do Trung Kien 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.2
Rice husk is a waste product of agricultural production of rice. Every year, the agricultural production of Vietnam emits about10 million tons of rice husks. Rice husks are usually treated by burning method or discharged into rivers, causing manynegative impacts on the environment. In this study, the rice husk/silica gel ratio components were investigated to form SiC/SiO2-C composite in a CO2 environment at 1000 oC for 60 min. The products after pyrolysis were determined SiC, SiO2, andfree C contents according to ISO 21068-2: 2008 standards. The functional groups and mineral composition of composites wereanalyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The microstructure and elementdistribution of them were observed by scanning electron microscope (SEM) and Energy-dispersive X-ray (EDX) mapping. Theresults showed that the optimum rice husk/silica gel ratio to form SiC/SiO2-C was 1.4/1. The sample after pyrolysis hadchemical composition including 14% SiC, 63% SiO2, 23% free C (%wt.) and the phase composition including amorphouscarbon, β-SiC, 6H-SiC, 4H-SiC, cristobalite. Composite SiC/SiO2-C can apply to advanced friction systems. This can be seenas an effective method to treat rice husk waste and improved the economic value of rice plants.
An Omnidirectionally Stretchable Photodetector Based on Organic–Inorganic Heterojunctions
Trung, Tran Quang,Dang, Vinh Quang,Lee, Han-Byeol,Kim, Do-Il,Moon, Sungjin,Lee, Nae-Eung,Lee, Hoen American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.41
<P>Omnidirectionally stretchable photodetectors are limited by difficulties in designing material and fabrication processes that enable stretchability in multiaxial directions. Here, we propose a new approach involving an organic inorganic p-n heterojunction photodetector comprised of free-standing ZnO nanorods grown on a poly(3,4ethylenedioxythiophene)-polystyrene sulfonate transport layer coated on a three-dimensional micropatterned stretchable substrate containing bumps and valleys. This structure allows for efficient absorption of stretching strain. This approach allows the device to accommodate large tensile strain in all of the directions. The device behaves as a photogated p-n heterojunction photodetector in which current modulation was obtained by sensing the mechanisms that rely on photovoltage and photogating effects. The device exhibits a high photoresponse to UV light and reliable electrical performance under applied stretching in uniaxial and omniaxial directions. Furthermore, the device can be easily and conformally attached to a human wrist. This allowed us to investigate the response of the device to UV light during human activity.</P>
Kieu Do Trung Kien,Do Quang Minh 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1
Woodceramics is carbon ceramics with porous structures that can be used in many technical fields. In this study,woodceramics was prepared by mixing cashew nut shell waste (CNSW) and liquefied wood with a ratio of 1/0.6 and thensintered in an inert atmosphere at 700 oC-1200 oC. The influence of sintering temperature on the carbonization behavior offormed woodceramics was determined by X-ray diffraction, Fourier transforms infrared spectroscopy, Isotope Ratio MassSpectrometry measurement, and Scanning Electron Microscope/ Energy Dispersive X-Ray Analysis techniques. Theexperimental results showed that the carbon content increased when the sintering temperature increased. In addition to theincreased carbon content, the degree of graphitization of woodceramics also increased. It is represented by an increasedintensity of the (002) peaks and a decrease in the d002 value on the X-ray diffraction patterns. The SEM/EDX results alsoshowed that appeared small graphite particles in the amorphous background at 1000 oC-1200 oC. However, the d002 value ofthe samples is only in the range of 0.3339-0.4094 nm, so the structure of the formed carbon is a non-graphite structure.
Study on sintering process of woodceramics from the cashew nutshell waste
Kieu Do Trung Kien,Phan DinhTuan,Toshihiro Okabe,Do Quang Minh,Tran Van Khai 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.6
In this study, the sintering mechanism of woodceramics (WCs) from cashew nut shell waste (CNSW) was studied by analyzingchemical reactions and structural changes during the sintering process of of CNSW powder, liquefied wood and green bodiesof WCs at 900 oC for 60 minutes in the CO2 atmosphere. The chemical and structural properties of the products wereinvestigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared (FTIR), and scanning electronmicroscope (SEM). The results showed that the decomposition reactions of liquefied wood and CNSW occurred simultaneouslyto form the hard carbon and the soft carbon at high temperature. The sintering mechanism of WCs has been presented.
Siddiqui, Saqib,Kim, Do-Il,Roh, Eun,Duy, Le Thai,Trung, Tran Quang,Nguyen, Minh Triet,Lee, Nae-Eung Elsevier 2016 Nano energy Vol.30 No.-
<P><B>Abstract</B></P> <P>Practical usage of piezoelectric nanogenerators (PENGs) under heavy loading environments for high power generation, such as smart shoes, has been limited due to the low mechanical endurance of many piezoelectric materials. Durability and performance under harsh environments are a stumbling block for the practical application of PENGs. Synthesis of piezoelectrically enhanced nanofibers electrospun from nanocomposite of barium titanate nanoparticles (BT NPs) dispersed in poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) enables successful fabrication of a robust, efficient, flexible and lead-free PENG. A nanofiber PENG (nf-PENG) fabricated by embedding nanocomposite nanofibers in an elastomer film is demonstrated for biomechanical energy harvesting and storage during walking. When placed inside of a shoe, a nf-PENG loaded with 15wt% BT NPs can generate an output of 25V at a walking frequency of 0.6Hz with high mechanical durability under very high loads (600N). This can charge a 4.7µF capacitor after approximately 72 steps. The stored charge can operate a strain sensor without any external power supply. The high performance of the nf-PENG is mainly attributed to the self-poled nanocomposite nanofibers. Additionally, embedding the nanofibers into an elastomer provided high durability by protecting the nanofibers from mechanical damage. Furthermore, the devices small form factor, flexibility, and transparency make this nf-PENG suitable for applications in wearable electronics, where aesthetics and comfort are also desired (in addition to performance). This work demonstrates the possibility of highly durable, efficient, and self-powered wearable sensing systems that can work under extreme environments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lead-free piezoelectric nanocomposite nanofibers. </LI> <LI> High durability under harsh environments and high loadings. </LI> <LI> Harvesting and storing biomechanical energy during walking. </LI> <LI> Self-powered system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A highly durable, efficient and flexible piezoelectric nanogenerator, comprised of piezoelectric nanocomposite nanofibers embedded into an elastomer, was designed for energy harvesting under heavy loading conditions. The high resistance of the generator to ambient conditions for prolonged periods of time, as well as resistance to damage under heavy loading conditions, enabled the efficient harvest of bio-mechanical energy during human walking. This energy could be stored in a capacitor to create a self-powered sensor system. This approach may help enable practical applications of piezoelectric nanogenerators in wearable systems.</P> <P>[DISPLAY OMISSION]</P>