http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Horbatenko, Yevhen (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
Horbatenko, Y.,Yousaf, M.,Lee, J.,Choi, T.H.,Ruoff, R.S.,Park, N. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.106 No.-
<P>The effects of the interplay between pressure and surface chemistry on the transformation of few-layer graphene into an sp(3)-bonded carbon film were investigated with first-principles density functional theory calculations including ab initio molecular dynamics. N2H4, H2O, and He were each considered as a candidate pressure medium. Compared with the bulk graphite, the surface chemistry overwhelmingly governed the conversion energetics for nanometer-thick graphene layers. A hydrogen-donating medium reduced the required conversion pressure compared with an inert one; the conversion pressure obtained by using N2H4 was 40% of the corresponding pressure obtained with He. We suggest that pressurizing the cell through hydrogen-donating pressure media has the advantage from the surface chemistry by concentrating hydrogen atoms on carbon surfaces. (C) 2016 Elsevier Ltd. All rights reserved.</P>
-
Horbatenko, Yevhen,Shin, Dongbin,Han, Sang Soo,Park, Noejung Elsevier 2018 Chemical physics letters Vol.694 No.-
<P><B>Abstract</B></P> <P>The microscopic effect of electronic excitations on the transformation of few-layer graphene into sp<SUP>3</SUP>-bonded carbon nanofilm is examined through static and real-time propagation time-dependent density-functional theory. Statically, the presence of holes in high-lying valence bands is shown to reduce the energy barrier substantially. Dynamics of excited state electrons combined with Ehrenfest atomic motions reveals that non-thermal fast transformation from sp<SUP>2</SUP> to sp<SUP>3</SUP> can happen within a few hundreds femtoseconds. We suggest that once the efficient path of sp<SUP>3</SUP> carbon surface passivation is provided, the excitation from π to <SUP> π ∗ </SUP> bands of few-layer graphenes can be utilized to achieve the transformation into nanoscale sp<SUP>3</SUP>-bonded carbon film without heating process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First-principles excited state calculation using real-time TDDFT. </LI> <LI> Ehrenfest dynamics study of the phase transition between sp2-phase and sp3-phase carbon. </LI> <LI> Non-thermal phase transition induced by excited states of π electrons. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
-
First-principles investigation of wet-chemical routes for the hydrogenation of graphene
Horbatenko, Yevhen,Choi, Min,Ruoff, Rodney S.,Bielawski, Christopher W.,Park, Noejung Elsevier 2015 Carbon Vol.93 No.-
<P><B>Abstract</B></P> <P>To investigate the microscopic mechanism for the wet-chemical hydrogenation of graphene, first principles density functional calculations were performed for the hydrogen transfer reaction between the graphene surface and a mixture of hydrogen carrier and electron donor. For the hydrogen transfer from CH<SUB>3</SUB>OH to graphene, as commonly used in Birch-type reductions, the presence of alkali atoms is important not only because they donate electrons but also stabilize the CH<SUB>3</SUB>O<SUP>−</SUP>. On the other hand, when a hydrogen carrier becomes charge neutral after the transfer, as for the case of CH<SUB>3</SUB>NH<SUB>3</SUB> <SUP>+</SUP>, the presence of alkali atoms is not essential, and the supply of electrons from an external source can lead to as favorable thermodynamics as that of alkali atoms. We suggest that, based on these results, a potentially more efficient experimental procedure can be designed.</P>
-
Shostak, Svetlana,Kim, Kitae,Horbatenko, Yevhen,Choi, Cheol Ho American Chemical Society 2019 The journal of physical chemistry. A, Molecules, s Vol.123 No.39
<P>With the help of quantum mechanical methods, the formation of H<SUB>2</SUB>SO<SUB>4</SUB> by the oxidation of H<SUB>2</SUB>SO<SUB>3</SUB> with H<SUB>2</SUB>O<SUB>2</SUB> was studied theoretically. Both stepwise and concerted mechanisms were calculated. It was found that the direct oxidation of H<SUB>2</SUB>SO<SUB>3</SUB> by H<SUB>2</SUB>O<SUB>2</SUB> alone requires prohibitive activation energies of >38.6 kcal/mol. However, the addition of one water molecule exhibits a strong catalytic effect that dramatically reduces the overall reaction barrier to 6.2 (2.3 with PCM) kcal/mol. The deprotonated HSO<SUB>3</SUB><SUP>-</SUP> species also reduces the overall reaction barrier to 5.6 (−5.8 with PCM) kcal/mol. Both of these proceed via concerted pathways. On the other hand, the stepwise mechanisms generally produce intermediates with a hydroperoxy group (−O-O-H), which is a result of a nucleophilic attack by the oxygens of H<SUB>2</SUB>O<SUB>2</SUB>. While studying the catalytic effect of water, a previously unknown hydroperoxy intermediate (HOO)S(OH)<SUB>3</SUB>, where sulfur is coordinated with three OH groups, was found. This work also reveals a rearrangement step of another hydroperoxy intermediate (HOO)SO<SUB>2</SUB><SUP>-</SUP> to HSO<SUB>4</SUB><SUP>-</SUP> that was found in earlier experimental studies. For all of the mechanisms calculated, the final H<SUB>2</SUB>SO<SUB>4</SUB> is formed with a significant exothermicity of >60 kcal/mol. In general, even without sunlight, it was found that the formation of sulfuric acid by hydrogen peroxide can occur in a heterogeneous moisturized environment.</P> [FIG OMISSION]</BR>
-
Nayak, Pramoda K.,Horbatenko, Yevhen,Ahn, Seongjoon,Kim, Gwangwoo,Lee, Jae-Ung,Ma, Kyung Yeol,Jang, A-Rang,Lim, Hyunseob,Kim, Dogyeong,Ryu, Sunmin,Cheong, Hyeonsik,Park, Noejung,Shin, Hyeon Suk American Chemical Society 2017 ACS NANO Vol.11 No.4
<P>Interlayer excitons were observed at the heterojunctions in van der Waals heterostructures (vdW HSs). However, it is not known how the excitonic phenomena are affected by the stacking order. Here, we report twist-angle-dependent interlayer excitons in MoSe2/WSe2 vdW HSs based on photoluminescence (PL) and vdW-corrected density functional theory calculations. The PL intensity of the interlayer excitons depends primarily on the twist angle: It is enhanced at coherently stacked angles of 0 degrees and 60 degrees (owing to strong interlayer coupling) but disappears at incoherent intermediate angles. The calculations confirm twist-angle-dependent interlayer coupling: The states at the edges of the valence band exhibit a long tail that stretches over the other layer for coherently stacked angles; however, the states are largely confined in the respective layers for intermediate angles. This interlayer hybridization of the band edge states also correlates with the interlayer separation between MoSe2 and WSe2 layers. Furthermore, the interlayer coupling becomes insignificant, irrespective of twist angles, by the incorporation of a hexagonal boron nitride monolayer between MoSe2 and WSe2.</P>
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
