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RISS 인기검색어
- 검색키워드
- 저자 : Nazarian-Samani, Masoud (검색결과 4 건)
- 무료
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A robust design of Ru quantum dot/N-doped holey graphene for efficient Li-O2batteries
Nazarian-Samani, Masoud,Lim, Hee-Dae,Haghighat-Shishavan, Safa,Kim, Hyun-Kyung,Ko, Youngmin,Kim, Myeong-Seong,Lee, Suk-Woo,Kashani-Bozorg, Seyed Farshid,Abbasi, Majid,Guim, Hwan-Uk,Kim, Dong-Ik,Roh, K The Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.2
<P>Herein, we report a simple, versatile, defect-engineered method to fabricate Ru quantum dots (Ru QDs) uniformly anchored on a nitrogen-doped holey graphene (NHG) monolith. It uses<I>in situ</I>pyrolysis of mixed glucose, dicyandiamide (DCDA), and RuCl3, followed by an acid treatment, and a final heat treatment to introduce in-plane holes of various sizes. A novel transmission method in scanning electron microscopy was successfully implemented to directly visualize the holes with color contrast. A low accelerating voltage of 5 kV enabled prolonged observation without significant electron beam damage. The mechanisms of hole creation were examined in detail using various characterization techniques as well as control experiments. The Ru QDs had significant catalytic activity and resulted in larger in-plane holes through the graphene sheets. The mechanical strain and the chemical reactivity of Ru QDs significantly diminished the activation energy barrier for the oxidation of CC bonds in the graphene structure. The Ru QD/NHG hybrid material was utilized as an electrocatalyst for the oxygen evolution reaction in Li-O2batteries, showing much lower charge overpotentials compared to the bare NHG counterpart. The defect-laden holey graphene counterpart can be highly functionalized for multiple applications, leading to a new method of nanoengineering based on atomic scale defects.</P>
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Rational hybrid modulation of P, N dual-doped holey graphene for high-performance supercapacitors
Nazarian-Samani, Masoud,Haghighat-Shishavan, Safa,Nazarian-Samani, Mahboobeh,Kim, Myeong-Seong,Cho, Byung-Won,Oh, Si-Hyoung,Kashani-Bozorg, Seyed Farshid,Kim, Kwang-Bum Elsevier Sequoia 2017 Journal of Power Sources Vol. No.
<P><B>Abstract</B></P> <P>A P, N dual-doped holey graphene (PNHG) material is prepared by a scalable, facile synthetic approach, using a mixture of glucose, dicyandiamide (DCDA), and phosphoric acid (H<SUB>3</SUB>PO<SUB>4</SUB>). H<SUB>3</SUB>PO<SUB>4</SUB> successfully functions as an “acid catalyst” to encourage the uniform breakage of C=C bonds to create large, localized perforations over the graphene monolith. Further acid treatment and annealing introduce in-plane holes. The correlation between the capacitance of the PNHG and its structural parameters during the fabrication process is comprehensively evaluated. A thermally induced sp<SUP>2</SUP>→sp<SUP>3</SUP> transformation occurs at high temperatures because of the substantial loss of graphitic sp<SUP>2</SUP>-type carbons, together with a dramatic reduction in capacitance. The target PNHG-400 electrode material delivers exceptionally high gravimetric capacitance (235.5 F g<SUP>−1</SUP> at 0.5 A g<SUP>−1</SUP>), remarkable rate capability (84.8% at 70 A g<SUP>−1</SUP>), superior capacitance retention (93.2 and 92.7% at 10 and 50 A g<SUP>−1</SUP> over 25000 cycles, respectively), and acceptable volumetric capacitance due to moderate density, when it is used with organic electrolytes in the voltage range between 0 and 3 V. These results suggest a pioneering defect-engineered strategy to fabricate dual-doped holey graphene with valuable structural properties for high-performance electric double layer supercapacitors, which could be used in next-generation energy storage applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rationally designed P, N dual-doped holey graphene as an electrode in supercapacitors. </LI> <LI> Importance of synergistic ion transport with a high content of C=C bonds. </LI> <LI> Occurrence of sp<SUP>2</SUP>→sp<SUP>3</SUP> transition in graphene structure at temperatures higher than 400 °C. </LI> <LI> High capacitance, excellent rate capability and cyclic stability of the target PNHG-400. </LI> <LI> Novel approach to develop future supercapacitors with high energy and power densities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Fabrication of well-designed defect-laden holey graphene counterparts for energy-related applications using a simple, up-scalable and cost-effective strategy.</P> <P>[DISPLAY OMISSION]</P>
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Haghighat-Shishavan, Safa,Nazarian-Samani, Masoud,Nazarian-Samani, Mahboobeh,Roh, Ha-Kyung,Chung, Kyung-Yoon,Cho, Byung-Won,Kashani-Bozorg, Seyed Farshid,Kim, Kwang-Bum The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.21
<P>We report a new composite of black phosphorus and multiwall carbon nanotubes (BP-CNT) prepared <I>via</I> a surface oxidation-assisted chemical bonding procedure. The controlled air exposure successfully changed the naturally hydrophobic BP powder to the desired hydrophilicity, which was found indispensable to stable bond formation between the BP and the functionalized CNTs during ball milling. The BP-CNT composites were further fabricated into anodes for both Li- and Na-ion batteries, using a sodium carboxyl methyl cellulose-poly(acrylic acid) (NaCMC-PAA) binary polymeric binder. The hydrophilicity of BP also played a very important role in forming strong bonds with the hydroxyl groups of NaCMC and the carboxylic acid groups of PAA. The plausible mechanisms of stable bond formation were comprehensively examined, and the results revealed two types of strong connections: P-O-C bonds and dehydration cross links. Consequently, the material delivered outstanding electrochemical performance in the anode, with a high discharge capacity of 1681 mA h g<SUP>−1</SUP> after 400 cycles at a current density of 0.2C (1C = 2596 mA g<SUP>−1</SUP>) for Li-ion batteries. It also successfully delivered a first discharge capacity of 2073 and 850 mA h g<SUP>−1</SUP> at 0.2C and 2C for Na-ion batteries, respectively, with excellent capacity retentions at both rates after 200 cycles. These salient results, which originated from the modified hydrophilic BP, will give further impetus to explore BP-based composites for use as high-performance materials for advanced energy storage applications.</P>
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Bulk metal-derived metal oxide nanoparticles on oxidized carbon surface
Kim, Hyun-Kyung,Aravindan, Vanchiappan,Mhamane, Dattakumar,Yoon, Seung-Beom,Park, Sang-Hoon,Nazarian-Samani, Masoud,Han, Joong Tark,Park, Ho Seok,Roh, Kwang Chul,Kim, Kwang-Bum Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.752 No.-
<P><B>Abstract</B></P> <P>Nano-sized metal oxides have gained widespread interest because of their multifarious applications in catalysis, energy storage, semiconductors, and nanomedicine. Though many viable solution-based techniques for the preparation of nanoparticles (NPs) have been reported, meeting efficiency and scalability requirements remains challenging. Here, we demonstrate the generalized and facile method to yield metal oxide NPs that exploit bulk metal particulates. Based on a galvanic reaction, the interface between bulk metal powder and oxidized carbonaceous material transforms metals in to oxide/hydroxide NPs on the carbonaceous surface, owing to the resulting potential difference. This preparation procedure uses a solution-based synthesis technique, which is relatively straightforward, eco-friendly, scalable, inexpensive, and can be easily executed for a variety of metals; for instance, we demonstrated this approach for Zn, Ni, Co, Sn and Cu.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simple method for producing metal oxide nanoparticle composites is described. </LI> <LI> Readily available bulk metals were converted to metal oxide nanoparticle composites. </LI> <LI> The resulting composites were tested as electrode materials in supercapacitors. </LI> <LI> This method can be used for a variety of metals. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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