Oxygen adsorption on single layer graphyne: a DFT study

Kang, Baotao,Liu, Hongguang,Lee, Jin Yong The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.3

<P>Graphyne is a rising two-dimensional (2D) carbon allotrope with excellent electronic properties. In this paper, theoretical calculations were performed to study the corresponding electronic properties of the oxygenated graphyne. Atomic oxygen when bound to the carbon atom of graphyne forms a stable oxide, with a much larger binding energy compared to that on graphene. Owing to the oxygen adsorption, the α- and β-graphyne change from a zero-band-gap material to a semiconductor as indicated in the band structure calculations. Moreover, spin splitting was observed from the band structure of the oxygenated γ-graphyne. These electronic properties are tunable by altering the oxygen coverage through changing the supercell size. Our results based on the first-principles calculations imply that oxygenation is a promising method to functionalize graphyne to achieve designated properties.</P> <P>Graphic Abstract</P><P>In this paper, theoretical calculations were performed to study the corresponding electronic properties of oxygenated graphyne. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cp53237b'> </P>

Electronic Structures and Charge Transport of Stacked Annelated β-Trithiophenes

Liu, Hongguang,Kang, Sunwoo,Lee, Jin Yong American Chemical Society 2011 The Journal of physical chemistry B Vol.115 No.18

<P>Density functional theory (DFT) calculations were performed using a MPWB1K functional to interpret the charge transport (CT) properties of stacked annelated β-trithiophene molecules. The goal was to help understand how the chemical composition, face-to-face stacking, intra- and intermolecular correlations, and the applied electric field affect the CT properties of this organic semiconductor compared with those of the edge-to-face “herringbone” motif. The variations in the frontier molecular orbitals, energy gap, nonadiabatic electron attachment energies (EAE), and vertical detachment energies (VDE) were investigated under an external electric field as a function of the number of stacked layers (<I>n</I>). Two possible CT pathways, monomer-to-monomer (MM) and dimer-to-dimer (DD) transports, were postulated to determine the charge carrier conductivities of these molecules. The results highlight that the intermolecular electronic couplings and electrostatic interactions can significantly affect the stacking geometry, even in more extended structures; displaced stacks with smaller interlayer spacing resulted in more compact stacking and, thus, higher CT efficiency; face-to-face stacking geometries can help to reduce the energy gap and VDE. Despite the fact that common thiophene-based oligomers adopting edge-to-face herringbone motifs exhibited p-type (hole-transporting) characters, the face-to-face stacked models based on annelated β-trithiophenes exhibited remarkably increased n-type (electron-transporting) performances. The electric field in the <I>z</I>-direction produced a small influence on the DD charge transport, whereas both electron and hole mobilities decreased dramatically in the MM case. More importantly, in MM charge transport, the electric field increases the hole mobility so that it is higher than that of the electron.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2011/jpcbfk.2011.115.issue-18/jp1045595/production/images/medium/jp-2010-045595_0008.gif'></P>

Hidden Role of a Hydroxyl Group in Mediating the Oxygen Line Defect on a Graphene Surface

Liu, Hongguang,Kang, Baotao,Lee, Jin Yong American Chemical Society 2013 The Journal of Physical Chemistry Part C Vol.117 No.34

<P>Atomic fault lines stemming from the linear assembly of epoxy groups are recently proposed to be responsible for the decrease of bulk size of graphitic materials. Yet, the formation of such a line by either the hopping of existing epoxides or the binding with environmental atomic oxygens seems to be infeasible. By employing both finite and periodic graphene models, we uncovered the role of hydroxyl, which is essentially ignored in previous reports, in mediating the epoxy line. It is noteworthy that the intercalation of OH impedes the unzipping of underlying carbons and induces a smoother surface buckling along the epoxy line. The fault line formation would be ascribed to the creation of vacancies when the system temperature elevates.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-34/jp4052159/production/images/medium/jp-2013-052159_0010.gif'></P>

중국 단동 지역에서 국내 벼 품종의 출수 반응과 적응 출수생태 특성

양운호(Woonho Yang),Hongguang Ju,김정주(Jeong-Ju Kim),한아름(Areum Han),양정욱(Jung-Wook Yang),김은영(Eun Young Kim),강신구(Shingu Kang),이대우(Dae-Woo Lee),채미진(Mi-jin Chae),신명나(Moung Na Shin),Dongchun Jin,Jin Piao,Jichun 한국작물학회 2023 한국작물학회지 Vol.68 No.3

1. 벼 재배기간에 단동 지역의 평균기온은 북한의 신의주보다 약간 낮게, 수풍보다는 약간 높게 경과하였으며, 이들세 지역의 일장 변화는 거의 동일하였다. 2. 시험 연도와 이앙시기에서 공통적으로 단동 지역의 안전출수한계기와 현지 품종 중 가장 늦은 출수기까지 출수한 국내 품종은 조생종 8개(진부올, 백일미, 조운, 진옥, 조평, 진부, 산호미, 오대)였으며, 북한 품종은 5개(올벼2, 선봉9, 온포1, 길주1, 평도15)였다. 3. 국내 13품종과 북한 7품종의 기본영양생장성은 12~43 일, 감광성은 3~56일, 감온성은 15~33일 범위였는데, 국내 중생 및 중만생 3품종(선품, 신보, 소비)과 북한 평양21은 감광성이 33~56일로 컸고, 다른 3품종(아세미, 진미, 평도5)은 기본영양생장성이 40~43일로 큰 특징을 보였다. 4. 단동 시험포장에서 나타난 벼 품종의 출수기는 감광성과고도로 유의한 정의 상관을 나타내었으며, 감광성이 컸던 중생과 중만생 3품종을 제외하면 기본영양생장성과유의한 정의 상관관계가 인정되었다. 5. 단동 지역의 벼 재배기간에 적응하는 품종은 기본영양생장성 35일 이하와 감광성 25일 이하를 모두 충족하는 출수생태 특성을 보였다. We examined the heading responses of rice varieties over two years in Dandong, China to select the varieties that are adaptable to the bordering northwestern plains of North Korea. Dandong had slightly lower mean temperature than Sinuiju, North Korea but slightly higher than Supung, but it had almost the same day-length as the two regions in North Korea. In the two experimental years and two transplanting-date treatments, eight varieties (Jinbuol, Baegilmi, Joun, Jinok, Jopyeong, Jinbu, Sanhomi, and Odae) from South Korea and five varieties (Olbyeo2, Sonbong9, Onpo1, Gilju1, and Pyongdo5) from North Korea reached the heading stage not later than the latest heading dates of Dandong domestic varieties and the safe marginal heading dates of Dandong. We examined the basic vegetative phase (BVP), photoperiod-sensitivity (PS), and thermo-sensitivity (TS) of rice heading in a phytotron study to characterize the heading ecotypes of rice varieties adaptable to Dandong. For the rice varieties grown in Dandong experimental field, number of days to the heading stage was highly positively correlated with PS and, except middle and mid-late maturing three varieties, it was significantly positively correlated with BVP. Two-dimensional distribution plotting revealed that both 35 days or less BVP and 25 days or less PS were the characteristic heading ecotypes of the rice varieties adaptable to Dandong.

Mechanism of Tungsten Recovery from Spent Cemented Carbide by Molten Salt Electrodeposition

Hongxuan Xing,Zhen Li,Enrui Feng,Xiaomin Wang,Hongguang Kang,Yiyong Wang,Hui Jin,Jidong Li The Korean Electrochemical Society 2023 Journal of electrochemical science and technology Vol.14 No.1

The accumulation of spent carbide (YG8), not only pollutes the environment but also causes waste of tungsten, cobalt and other rare metal resources. To better address this issue, we proposed a combined electrochemical separation process of low-temperature aqueous solution and high-temperature molten salt for tungsten and cobalt. H₂WO₄ was obtained from spent carbide in an aqueous solution, and we calcined it to obtain WO₃, which was used as a raw material to obtain tungsten by using molten salt electrodeposition. The influence of the current efficiency and the electrochemical behavior of the discharge precipitation of W(VI) were also studied. The calcination results showed that the morphology of WO₃ was regular and there were no other impurities. The maximum current efficiency of 82.91% was achieved in a series of electrodeposition experiments. According to XRD and SEM analysis, the recovered product was high purity tungsten, which belongs to the simple cubic crystal system. In the W(VI) reduction mechanism experiments, the electrochemical process of W(VI) in NaCl-Na₂WO₄-WO₃ molten salt was investigated using linear scanning voltammetry (LSV) and chronoamperometry in a three-electrode system. The LSV showed that W(VI) was reduced at the cathode in two steps and the electrode reaction was controlled by diffusion. The fitting results of chronoamperometry showed that the nucleation mechanism of W(VI) was an instantaneous nucleation mode, and the diffusion coefficient was 7.379×10^-10 cm²·s^-1.