Hierarchical Cu nanoparticle-aggregated cages with high catalytic activity for reduction of 4-nitrophenol and carbon dioxide

Jiang, Jianwei,Gunasekar, Gunniya Hariyanandam,Park, Sanghyuk,Kim, Sang-Ho,Yoon, Sungho,Piao, Longhai Elsevier 2018 Materials research bulletin Vol.100 No.-

<P><B>Abstract</B></P> <P>Hierarchical ∼10 nm Cu nanoparticle (NP)-aggregated sub-micro cage catalysts (diameter: ∼800 nm) with a hollow interior and porous shell were prepared from SiO<SUB>2</SUB> encapsulated Cu<SUB>2</SUB>O nanoparticle aggregates (NPAs) using a facile and scalable method. The Cu cages were analyzed by field emission-scanning electron microscopy (FE-SEM), energy-dispersed X-ray (EDX), transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction (SAED), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). Owing to the small primary Cu NPs and characteristic porous shell and hollow interior, the Cu cages showed an extraordinarily high catalytic activity in the reduction of 4-nitrophenol by NaBH<SUB>4</SUB> in aqueous solution. The activity factor (<I>K</I> = 520 s<SUP>−1</SUP> g<SUP>−1</SUP>) is approximately 2.8 times greater than the previous highest <I>K</I> value of unsupported Cu catalysts. In addition, the excellent catalytic activity of the Cu cages in hydrogenation of CO<SUB>2</SUB> to formate, with a TON value of 58 at 200 °C, was comparable to that of various noble metal-supported heterogeneous catalysts and surpassed the vast majority of homogeneous first-row transition metal catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesizing a challenging structure, hierarchical ∼10 nm Cu NP-aggregated sub-micro cages. </LI> <LI> Cu cages showed an excellent catalytic activity in the reduction of 4-nitrophenol by NaBH<SUB>4</SUB>. </LI> <LI> This is the first report on using a Cu NP-based heterogeneous catalyst for the hydrogenation CO<SUB>2</SUB> to formate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hollow porous Cu particles from silica-encapsulated Cu2O nanoparticle aggregates effectively catalyze 4-nitrophenol reduction

Jiang, Jianwei,Soo Lim, Young,Park, Sanghyuk,Kim, Sang-Ho,Yoon, Sungho,Piao, Longhai The Royal Society of Chemistry 2017 Nanoscale Vol.9 No.11

<P>A hollow metal micro/nanomaterial with a porous wall is one of the most attractive structures for catalysts. The synthesis of hollow porous Cu particles remains a challenge due to their air-sensitive characteristics. In this study, we report a facile and scalable method for the preparation of high-quality hollow porous Cu particles in the range of 500 nm-1.5 mu m with a well-defined structure from Cu2O nanoparticle aggregates (NPAs). The synthetic procedure involves the silica-encapsulation and depth-controlled reduction of Cu2O NPAs followed by heat-treatment in air and selective removal of the encapsulating layer. The catalytic performance of the hollow porous Cu particles was evaluated through the catalytic reduction of 4-nitrophenol with NaBH4 as a model reaction. The hollow porous Cu particles exhibited a high activity factor, K = 186 s(-1) g(-1), which is the highest K value obtained among the unsupported Cu catalysts to date. And the K value is better than that of some noble metal catalysts, such as Au, Ag, and Pd. In addition, the catalyst could be easily separated from the reaction system and still possessed high activity as well as stability in recycled reactions.</P>

High-temperature Adhesion Promoter Based on (3-Glycidoxypropyl) Trimethoxysilane for Cu Paste

Jianwei Jiang,구용환,Hye Won Kim,Ji Hyun Park,Hyun Suk Kang,이병철,김상호,송희은,Longhai Piao 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.10

To realize copper-based electrode materials for printed electronics applications, it is necessary to improve the adhesion strength between conductive lines and the substrate. Here, we report the preparation of Cu pastes using (3-glycidoxypropyl) trimethoxysilane (GPTMS) prepolymer as an adhesion promoter (AP). The Cu pastes were screen-printed on glass and polyimide (PI) substrates and sintered at high temperatures (> 250 oC) under a formic acid/N2 environment. According to the adhesion strengths and electrical conductivities of the sintered Cu films, the optimized Cu paste was composed of 1.0 wt % GPTMS prepolymer, 83.6 wt % Cu powder and 15.4 wt % vehicle. After sintering at 400 oC on a glass substrate and 275 oC on a PI substrate, the Cu films showed the sheet resistances of 10.0 mΩ/sq. and 5.2 mΩ/sq., respectively. Furthermore, the sintered Cu films exhibit excellent adhesion properties according to the results of the ASTM-D3359 standard test.

Living Ring-Opening Polymerization of β-Butyrolactone Initiated by Mononuclear Zirconium Compounds Containing Sterically Hindered N,O-Chelate and Anionic Dimethylamide Ligands

( Jiang Jianwei ),윤성호 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.0

High-temperature Adhesion Promoter Based on (3-Glycidoxypropyl) Trimethoxysilane for Cu Paste

Jiang, Jianwei,Koo, Yong Hwan,Kim, Hye Won,Park, Ji Hyun,Kang, Hyun Suk,Lee, Byung Cheol,Kim, Sang-Ho,Song, Hee-Eun,Piao, Longhai Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.10

To realize copper-based electrode materials for printed electronics applications, it is necessary to improve the adhesion strength between conductive lines and the substrate. Here, we report the preparation of Cu pastes using (3-glycidoxypropyl) trimethoxysilane (GPTMS) prepolymer as an adhesion promoter (AP). The Cu pastes were screen-printed on glass and polyimide (PI) substrates and sintered at high temperatures (> $250^{\circ}C$) under a formic acid/$N_2$ environment. According to the adhesion strengths and electrical conductivities of the sintered Cu films, the optimized Cu paste was composed of 1.0 wt % GPTMS prepolymer, 83.6 wt % Cu powder and 15.4 wt % vehicle. After sintering at $400^{\circ}C$ on a glass substrate and $275^{\circ}C$ on a PI substrate, the Cu films showed the sheet resistances of $10.0m{\Omega}/sq$. and $5.2m{\Omega}/sq$., respectively. Furthermore, the sintered Cu films exhibit excellent adhesion properties according to the results of the ASTM-D3359 standard test.

Photocatalytic degradation of 4‐nitrophenol by using multicomponent Cu 2 O‐Cu@TiO 2 nanoparticl

Jiang Jianwei,문석영,윤성호,Piao Longhai 대한화학회 2024 Bulletin of the Korean Chemical Society Vol.45 No.4

Multicomponent nanomaterials with synergistic effect were typically used to enhance the photocatalytic performance. Herein, three‐component nanomaterials composed of Cu 2 O, Cu, and TiO 2 were prepared using a facile method, and applied in the photocatalytic degradation reactions. The synthetic procedure involves the formation of Cu 2 O nanoparticle aggregates (NPAs) followed by Cu nanoparticles growth on the surface of Cu 2 O NPAs in one pot, and TiO 2 encapsulation (Cu 2 O‐Cu@TiO 2 ). The catalyst structure was characterized by x‐ray diffraction, field emission‐scanning electron microscopy, transmission electron microscopy, and energy‐dispersed x‐ray. The catalytic performance of Cu 2 O‐Cu@TiO 2 NPAs was evaluated through the photocatalytic degradation of 4‐nitrophenol under the simulated solar light. We found that it exhibited greater activity than the Cu 2 O‐Cu NPAs, commercial TiO 2 , and Cu 2 O@TiO 2 NPAs, probably due to their synergistic interactions resulting in the effective photogenerated carrier transfer in the multicomponent nanomaterials. Multicomponent nanomaterials with synergistic effect were typically used to enhance the photocatalytic performance. Herein, three-component nanomaterials composed of Cu2O, Cu, and TiO2 were prepared using a facile method, and applied in the photocatalytic degradation reactions. The synthetic procedure involves the formation of Cu2O nanoparticle aggregates (NPAs) followed by Cu nanoparticles growth on the surface of Cu2O NPAs in one pot, and TiO2 encapsulation (Cu2O-Cu@TiO2). The catalyst structure was characterized by x-ray diffraction, field emission-scanning electron microscopy, transmission electron microscopy, and energy-dispersed x-ray. The catalytic performance of Cu2OCu@ TiO2 NPAs was evaluated through the photocatalytic degradation of 4-nitrophenol under the simulated solar light. We found that it exhibited greater activity than the Cu2O-Cu NPAs, commercial TiO2, and Cu2O@TiO2 NPAs, probably due to their synergistic interactions resulting in the effective photogenerated carrier transfer in the multicomponent nanomaterials.

Modification of Polytetrafluoroethylene-fiberglass Composite Film Using Polydopamine Deposition with Improved Hydrophilicity

Zhiqing Jiang,Liang Jiang,Huiying Jia,Yanfen Zhou,Jianwei Ma,Shaojuan Chen 한국섬유공학회 2018 Fibers and polymers Vol.19 No.8

The surface of polytetrafluoroethylene (PTFE)-fiberglass composite film was modified with polydopamine (PDA) in order to improve hydrophilic properties and hence to expand its perspective usage for biomedical and blood-contacting applications. Scanning electron microscopy, atomic force microscopy, energy dispersive spectrometer and fourier transform infrared spectra were employed to analyse the surface morphology and the chemical structures of the modified PTFEfiberglass composite films. Hydrophilic property of PTFE-fiberglass composite films was investigated by using water contact angle measurement. The effect of treatment time on the surface morphology and hydrophilicity of PTFE-fiberglass composite films was investigated. The results showed that a dense layer of PDA was formed on PTFE-fiberglass composite films, the water contact angle decreased gradually with the increase in modification time. Moreover, the fastness of PDA layers deposited on the PTFE-fiberglass composite films was studied by using UV/VIS/NIR spectrometer. It was revealed that the PDA layer was stable in distilled water, 0.1 M hydrochloric acid solution and alcohol, but had a poor resistance to 0.1 M sodium hydroxide solution.

A New Operator Extracting Image Patch Based on EPLL

Jianwei Zhang,Tao Jiang,Yuhui Zheng,Jin Wang,Jiacen Xie 한국정보처리학회 2018 Journal of information processing systems Vol.14 No.3

Multivariate finite mixture model is becoming more and more popular in image processing. Performingimage denoising from image patches to the whole image has been widely studied and applied. However, thereremains a problem that the structure information is always ignored when transforming the patch into thevector form. In this paper, we study the operator which extracts patches from image and then transformsthem to the vector form. Then, we find that some pixels which should be continuous in the image patches arediscontinuous in the vector. Due to the poor anti-noise and the loss of structure information, we propose anew operator which may keep more information when extracting image patches. We compare the newoperator with the old one by performing image denoising in Expected Patch Log Likelihood (EPLL) method,and we obtain better results in both visual effect and the value of PSNR.

A New Operator Extracting Image Patch Based on EPLL

Zhang, Jianwei,Jiang, Tao,Zheng, Yuhui,Wang, Jin,Xie, Jiacen Korea Information Processing Society 2018 Journal of information processing systems Vol.14 No.3

Multivariate finite mixture model is becoming more and more popular in image processing. Performing image denoising from image patches to the whole image has been widely studied and applied. However, there remains a problem that the structure information is always ignored when transforming the patch into the vector form. In this paper, we study the operator which extracts patches from image and then transforms them to the vector form. Then, we find that some pixels which should be continuous in the image patches are discontinuous in the vector. Due to the poor anti-noise and the loss of structure information, we propose a new operator which may keep more information when extracting image patches. We compare the new operator with the old one by performing image denoising in Expected Patch Log Likelihood (EPLL) method, and we obtain better results in both visual effect and the value of PSNR.

High-Performance Stretchable Conductive Composite Fibers from Surface-Modified Silver Nanowires and Thermoplastic Polyurethane by Wet Spinning

Lu, Ying,Jiang, Jianwei,Yoon, Sungho,Kim, Kyung-Shik,Kim, Jae-Hyun,Park, Sanghyuk,Kim, Sang-Ho,Piao, Longhai American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.2

<P>Highly stretchable and conductive fibers have attracted great interest as a fundamental building block for the next generation of textile-based electronics. Because of its high conductivity and high aspect ratio, the Ag nanowire (AgNW) has been considered one of the most promising conducting materials for the percolation network-based conductive films and composites. However, the poor dispersibility of AgNWs in hydrophobic polymers has hindered their application to stretchable conductive composite fibers. In this paper, we present a highly stretchable and conductive composite fiber from the co-spinning of surface-modified AgNWs and thermoplastic polyurethane (PU). The surface modification of AgNWs with a polyethylene glycol derivative improved the compatibility of PU and AgNWs, which allowed the NWs to disperse homogeneously in the elastomeric matrix, forming effective percolation networks and causing the composite fiber to show enhanced electrical and mechanical performance. The maximum AgNW mass fraction in the composite fiber was 75.9 wt %, and its initial electrical conductivity was as high as 14 205 S/cm. The composite fibers also exhibited superior stretchability: the maximum rupture strain of the composite fiber with 14.6 wt % AgNW was 786%, and the composite fiber was also conductive even when it was stretched up to 200%. In addition, 2-dimensional (2-D) Ag nanoplates were added to the AgNW/PU composite fibers to increase the stability of the conductive network under repeated stretching and releasing. The Ag nanoplates acted as a bridge to effectively prevent the AgNWs from slippage and greatly improved the stability of the conductive network.</P>