Atomistic Interrogation of B–N Co-dopant Structures and Their Electronic Effects in Graphene

Schiros, Theanne,Nordlund, Dennis,Palova, Lucia,Zhao, Liuyan,Levendorf, Mark,Jaye, Cherno,Reichman, David,Park, Jiwoong,Hybertsen, Mark,Pasupathy, Abhay American Chemical Society 2016 ACS NANO Vol.10 No.7

<P>Chemical doping has been demonstrated to be an effective method for producing high-quality, large-area graphene with controlled carrier concentrations and an atomically tailored work function. The emergent optoelectronic properties and surface reactivity of carbon nanostructures are dictated by the microstructure of atomic dopants. Co-doping of graphene with boron and nitrogen offers the possibility to further tune the electronic properties of graphene at the atomic level, potentially creating p- and n-type domains in a single carbon sheet, opening a gap between valence and conduction bands in the 2-D semimetal. Using a suite of high-resolution synchrotron-based X-ray techniques, scanning tunneling microscopy, and density functional theory based computation we visualize and characterize B–N dopant bond structures and their electronic effects at the atomic level in single-layer graphene grown on a copper substrate. We find there is a thermodynamic driving force for B and N atoms to cluster into BNC structures in graphene, rather than randomly distribute into isolated B and N graphitic dopants, although under the present growth conditions, kinetics limit segregation of large B–N domains. We observe that the doping effect of these BNC structures, which open a small band gap in graphene, follows the B:N ratio (B > N, p-type; B < N, n-type; BN, neutral). We attribute this to the comparable electron-withdrawing and -donating effects, respectively, of individual graphitic B and N dopants, although local electrostatics also play a role in the work function change.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2016/ancac3.2016.10.issue-7/acsnano.6b01318/production/images/medium/nn-2016-01318z_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn6b01318'>ACS Electronic Supporting Info</A></P>

Connecting Dopant Bond Type with Electronic Structure in N-Doped Graphene

Schiros, Theanne,Nordlund, Dennis,Pá,lová,, Lucia,Prezzi, Deborah,Zhao, Liuyan,Kim, Keun Soo,Wurstbauer, Ulrich,Gutié,rrez, Christopher,Delongchamp, Dean,Jaye, Cherno,Fischer, Daniel American Chemical Society 2012 Nano letters Vol.12 No.8

<P>Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due to the potential of the two dimensional material to impact a range of device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is a sensitive probe of chemical bonding and electronic structure of chemical dopants introduced in single-sheet graphene films. In conjunction with density functional theory based calculations, we are able to obtain a detailed picture of bond types and electronic structure in graphene doped with nitrogen at the sub-percent level. We show that different N-bond types, including graphitic, pyridinic, and nitrilic, can exist in a single, dilutely N-doped graphene sheet. We show that these various bond types have profoundly different effects on the carrier concentration, indicating that control over the dopant bond type is a crucial requirement in advancing graphene electronics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-8/nl301409h/production/images/medium/nl-2012-01409h_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl301409h'>ACS Electronic Supporting Info</A></P>

Local Atomic and Electronic Structure of Boron Chemical Doping in Monolayer Graphene

Zhao, Liuyan,Levendorf, Mark,Goncher, Scott,Schiros, Theanne,Pá,lová,, Lucia,Zabet-Khosousi, Amir,Rim, Kwang Taeg,Gutié,rrez, Christopher,Nordlund, Dennis,Jaye, Cherno,Hybertsen, Mar American Chemical Society 2013 Nano letters Vol.13 No.10

<P>We use scanning tunneling microscopy and X-ray spectroscopy to characterize the atomic and electronic structure of boron-doped and nitrogen-doped graphene created by chemical vapor deposition on copper substrates. Microscopic measurements show that boron, like nitrogen, incorporates into the carbon lattice primarily in the graphitic form and contributes ∼0.5 carriers into the graphene sheet per dopant. Density functional theory calculations indicate that boron dopants interact strongly with the underlying copper substrate while nitrogen dopants do not. The local bonding differences between graphitic boron and nitrogen dopants lead to large scale differences in dopant distribution. The distribution of dopants is observed to be completely random in the case of boron, while nitrogen displays strong sublattice clustering. Structurally, nitrogen-doped graphene is relatively defect-free while boron-doped graphene films show a large number of Stone-Wales defects. These defects create local electronic resonances and cause electronic scattering, but do not electronically dope the graphene film.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-10/nl401781d/production/images/medium/nl-2013-01781d_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl401781d'>ACS Electronic Supporting Info</A></P>

Thermochemical degradation of cotton fabric under mild conditions

Michael Cuiffo,정혜정,Asta Skocir,Theanne Schiros,Emily Evans,Elizabeth Orlando,Yu-Chung Lin,Yiwei Fang,Miriam Rafailovich,Taejin Kim,Gary Halada 한국의류학회 2021 Fashion and Textiles Vol.8 No.1

Textile waste presents a major burden on the environment, contributing to climate change and chemical pollution as toxic dyes and finishing chemicals enter the environment through landfill leachate. Moreover, the majority of textile waste reaching landfills is discarded clothing, which could be reused or recycled. Here we investigate environmentally benign morphology changing of cotton textiles as a precursor for reintegration into a circular materials economy. At 50 °C using low concentrations of acids and bases, the interfiber structures of woven cotton were successfully degraded when treated with the following sequence of chemical treatment: citric acid, urea, sodium hydroxide, ammonium hydroxide, and sodium nitrate. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) reveal separation of the constituent fibers without depolymerization of the cellulose structure, and streaming potential measurements indicate that surface charge effects play a key role in facilitating degradation. The proposed reaction procedures show feasibility of effective waste-fabric recycling processes without chemically intensive processes, in which staple fibers are recovered and can be re-spun into new textiles.

Imaging chiral symmetry breaking from Kekulé bond order in graphene

Gutié,rrez, Christopher,Kim, Cheol-Joo,Brown, Lola,Schiros, Theanne,Nordlund, Dennis,Lochocki, Edward ,B.,Shen, Kyle M.,Park, Jiwoong,Pasupathy, Abhay N. Nature Publishing Group, a division of Macmillan P 2016 NATURE PHYSICS Vol.12 No.10

Chirality—or ‘handedness’—is a symmetry property crucial to fields as diverse as biology, chemistry and high-energy physics. In graphene, chiral symmetry emerges naturally as a consequence of the carbon honeycomb lattice. This symmetry can be broken by interactions that couple electrons with opposite momenta in graphene. Here we directly visualize the formation of Kekulé bond order, one such phase of broken chiral symmetry, in an ultraflat graphene sheet grown epitaxially on a copper substrate. We show that its origin lies in the interactions between individual vacancies in the copper substrate that are mediated electronically by the graphene. We show that this interaction causes the bonds in graphene to distort, creating a phase with broken chiral symmetry. The Kekulé ordering is robust at ambient temperature and atmospheric conditions, indicating that intercalated atoms may be harnessed to drive graphene and other two-dimensional materials towards electronically desirable and exotic collective phases.

Dopant Segregation in Polycrystalline Monolayer Graphene

Zhao, Liuyan,He, Rui,Zabet-Khosousi, Amir,Kim, Keun Soo,Schiros, Theanne,Roth, Michael,Kim, Philip,Flynn, George W.,Pinczuk, Aron,Pasupathy, Abhay N. American Chemical Society 2015 Nano letters Vol.15 No.2

<P>Heterogeneity in dopant concentration has long been important to the electronic properties in chemically doped materials. In this work, we experimentally demonstrate that during the chemical vapor deposition process, in contrast to three-dimensional polycrystals, the substitutional nitrogen atoms avoid crystal grain boundaries and edges over micron length scales while distributing uniformly in the interior of each grain. This phenomenon is universally observed independent of the details of the growth procedure such as temperature, pressure, substrate, and growth precursor.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-2/nl504875x/production/images/medium/nl-2014-04875x_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl504875x'>ACS Electronic Supporting Info</A></P>

Muslin Deweaving through Combined Mechanical, Thermal and Chemical Methods

Hang Zhang Cao,Jamie DeCoster,Jamie DeCoster,Kelvin Linskens,Kareem Mehdi,Yizhi Meng,Gary Halada,Hye-Jung Jung,Theanne Schiros,Asta Skocir,Taejin Kim 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11

Fabric waste has become an escalating problem that stems from the ever-shortening clothing lifecycle. Previouscotton recycling processes used mechanical methods to break the cotton down into fiber; this comes at the cost ofcompromised strength. Sodium hydroxide has long been used in the textile industry to increase dye absorption and lusterthrough mercerization. In this paper, the deweaving of cotton muslin fabric was attempted using the chemical interactions ofNaOH in combination with heat and mechanical forces through agitation. Different NaOH concentrations were tested todetermine the optimum condition for fabric decomposition on a laboratory scale. Overall, the muslin fabric treatment with0.5 M NaOH yielded the most promising results for fiber quality retention and chemical usage. The NaOH solution wasshown to be feasible in effectively deweaving multiple muslin fabrics consecutively. While the deweaving process reducesthe mechanical strength of the fabric, overall, the recycling method was successful in minimizing chemical waste anddeweaving time.