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Scalable bottom-up synthesis of Co-Ni–doped graphene
Introducing heteroatoms into graphene is a powerful strategy to modulate its catalytic, electronic, and magnetic properties. At variance with the cases of nitrogen (N)– and boron (B)–doped graphene, a scalable method for incorporating transition metal atoms in the carbon (C) mesh is currently lacking, limiting the applicative interest of model system studies. This work presents a during-growth synthesis enabling the incorporation of cobalt (Co) alongside nickel (Ni) atoms in graphene on a Ni(111) substrate. Single atoms are covalently stabilized within graphene double vacancies, with a Co load ranging from 0.07 to 0.22% relative to C atoms, controllable by synthesis parameters. Structural characterization involves variable-temperature scanning tunneling microscopy and ab initio calculations. The Co- and Ni-codoped layer is transferred onto a transmission electron microscopy grid, confirming stability through scanning transmission electron microscopy and electron energy loss spectroscopy. This method holds promise for applications in spintronics, gas sensing, electrochemistry and catalysis, and potential extension to graphene incorporation of similar metals.
The Triple Component Interface of Ni–Co–Ce: Growth, Chemical State, and Stability of NiCo Bimetallic Particles on Reducible CeO 2 (111) Thin Films
The growth of NiCo particles at low coverages over reducible CeO 2 (111) thin films producing a triple interface between Ni-Co-Ce was investigated by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), which was compared to that of monometallic Ni and Co particles. XPS data show that deposition of either Ni or Co on CeO 2 at 300 K causes a partial reduction of Ce 4+ cations to Ce 3+ ions. At 0.3 monolayer (ML), XPS detects Co 2+ on CeO 2 . However, both Ni 0 and Ni 2+ are present as major species at 300 K and annealing causes a significant increase of Ni 2+ in Ni particles. Deposition of 0.3 ML Co over 0.3 ML Ni on CeO 2 at 300 K induces reduction of Ni 2+ to metallic Ni and Ni 0 was found as predominant species. Unlike for Co/CeO 2 , metallic Co was also present over the Co-Ni/CeO 2 surface in addition to Co 2+ . Further, this behavior indicates the formation of NiCo bimetallic particles with the possibility of Co diffusion to the interface of Ni/ceria. With heating, the intermixing of Ni and Co atoms in bimetallic particles on CeO 2 was facilitated. Furthermore, oxidation of both metals and ceria occurred as a result of the diffusion of lattice oxygen from the bulk of ceria to the surface. A slight increase in Ni 2+ was observed after heating Co-Ni/CeO 2 to 500 K or higher. Co became Co 2+ with heating to 800 K. Our STM results confirm the formation of NiCo bimetallic particles on CeO 2 at 300 K and further suggest that the addition of Co can help inhibit the sintering of Ni particles at higher temperatures. Bimetallic particles were also obtained by depositing Ni over existing Co particles on CeO 2 . However, our XPS data demonstrate that the deposition order of Co and Ni plays a role in the chemical state of these two metals in bimetallic particles, likely attributed to the difference in their compositions at the bimetallic particle surface as well as the metal-support interface.
Cluster Expansion Analysis of Atomic Order in Li-Ion Battery Cathode Material LiCo y Ni 1-y O 2
A modified cluster-expansion treatment was developed recently to analyze atomic order in LiCo y Ni 1-y O 2 , a model cathode material for Li-ion batteries. In this treatment, referred to as a “spin-atom” cluster expansion, the occupant of a lattice site is identified by its spin state as well as its atomic species. Further, Effective Cluster Interaction (ECI) coefficients are derived from a large training data set (i.e., the set of atomic arrangements for which DFT calculations are performed) which is filtered by an anomaly detection algorithm to eliminate poorly converged DFT calculations. The cluster expansion incorporates Li-Ni (LN) exchange as well as intralayer Co-Ni (CN) exchange. Monte Carlo simulations based on the cluster expansion were applied to the Ni-rich part of the phase diagram. The simulations predict a miscibility gap between y = 0.05 and y = 0.65.
Superior analyses of iron meteorites.
Iron meteorites analysis for Ni, Co, P, C, S and Cu elements by milling technique, noting superiority degree based on Co-Ni correlation
Work strengthening by a deformation-induced phase transformation in 'MP Alloys'
Work strengthening and microstructure of Co-Ni base alloys containing Cr and Mo, discussing deformation induced martensitic transformation
Chemistry and thermal history of metal particles in Luna 20 soils.
Individual metal particles from Luna 20 thin sections 521, 513 and 514 as well as several small metallic inclusions in silicate particles from Luna 20 thin sections 501 and 502 were examined using optical microscopy and the electron microprobe. All the metallic particles and inclusions analyzed are of meteoritic Co-Ni content as are most of the metallic particles from the Fra Mauro and the Apollo 16 highlands sites. It is proposed that most of the metal at these 3 sites had its origin in the meteoritic projectiles that bombarded and accumulated in the early lunar crust. It is apparent that the metallic particles and some of the metallic inclusions in the Luna 20 soil have been subjected to reheating on the moon and this process has removed any evidence of the original meteoritic microstructure of the metal.
Metallic particles in the glassy constituents of three lunar highland samples 65315, 67435 and 78235
Electron probe microanalysis and analytical electron microscopy techniques were employed to obtain structural and chemical analyses of metal particles in the size range of less than 1000 A and greater than 5 microns from the glassy constituents of 3 lunar highland samples 65315, 67435 and 78235. Most of the micron size metal particles in the glass coatings of the three samples are of meteoritic Co-Ni content. The Ni content of submicron metal often differs significantly from the micron size metal in the same glass. This difference can be explained by one of 3 reasons: (a) the presence of metal of different sizes and Ni contents in the rock prior to the shock event, (b) the presence of metal particles in the lunar soil of meteoritic or variable Ni content which were incorporated when the glass formed and (c) the production of submicroscopic Fe metal from the reduction of Fe(+2) in the shock produced melt.
Materials Data on CoNi by Materials Project
CoNi is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Co is bonded in a body-centered cubic geometry to eight equivalent Ni atoms. All Co–Ni bond lengths are 2.43 Å. Ni is bonded in a body-centered cubic geometry to eight equivalent Co atoms.
Materials Data on Co3Ni by Materials Project
Co3Ni is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Co is bonded to eight equivalent Co and four equivalent Ni atoms to form CoCo8Ni4 cuboctahedra that share corners with twelve equivalent CoCo8Ni4 cuboctahedra, edges with eight equivalent NiCo12 cuboctahedra, edges with sixteen equivalent CoCo8Ni4 cuboctahedra, faces with four equivalent NiCo12 cuboctahedra, and faces with fourteen equivalent CoCo8Ni4 cuboctahedra. All Co–Co bond lengths are 2.48 Å. All Co–Ni bond lengths are 2.48 Å. Ni is bonded to twelve equivalent Co atoms to form NiCo12 cuboctahedra that share corners with twelve equivalent NiCo12 cuboctahedra, edges with twenty-four equivalent CoCo8Ni4 cuboctahedra, faces with six equivalent NiCo12 cuboctahedra, and faces with twelve equivalent CoCo8Ni4 cuboctahedra.
Materials Data on CoNi3 by Materials Project
Ni3Co1 is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Co is bonded to twelve equivalent Ni atoms to form CoNi12 cuboctahedra that share corners with six equivalent CoNi12 cuboctahedra, corners with twelve equivalent NiCo4Ni8 cuboctahedra, edges with eighteen equivalent NiCo4Ni8 cuboctahedra, faces with eight equivalent CoNi12 cuboctahedra, and faces with twelve equivalent NiCo4Ni8 cuboctahedra. There are six shorter (2.49 Å) and six longer (2.50 Å) Co–Ni bond lengths. Ni is bonded to four equivalent Co and eight equivalent Ni atoms to form NiCo4Ni8 cuboctahedra that share corners with four equivalent CoNi12 cuboctahedra, corners with fourteen equivalent NiCo4Ni8 cuboctahedra, edges with six equivalent CoNi12 cuboctahedra, edges with twelve equivalent NiCo4Ni8 cuboctahedra, faces with four equivalent CoNi12 cuboctahedra, and faces with sixteen equivalent NiCo4Ni8 cuboctahedra. There are six shorter (2.49 Å) and two longer (2.50 Å) Ni–Ni bond lengths.
Materials Data on CoNi3 by Materials Project
Ni3Co1 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Co is bonded to twelve equivalent Ni atoms to form CoNi12 cuboctahedra that share corners with twelve equivalent CoNi12 cuboctahedra, edges with twenty-four equivalent NiCo4Ni8 cuboctahedra, faces with six equivalent CoNi12 cuboctahedra, and faces with twelve equivalent NiCo4Ni8 cuboctahedra. All Co–Ni bond lengths are 2.49 Å. Ni is bonded to four equivalent Co and eight equivalent Ni atoms to form NiCo4Ni8 cuboctahedra that share corners with twelve equivalent NiCo4Ni8 cuboctahedra, edges with eight equivalent CoNi12 cuboctahedra, edges with sixteen equivalent NiCo4Ni8 cuboctahedra, faces with four equivalent CoNi12 cuboctahedra, and faces with fourteen equivalent NiCo4Ni8 cuboctahedra. All Ni–Ni bond lengths are 2.49 Å.
Materials Data on CoNi by Materials Project
CoNi is alpha La-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Co sites. In the first Co site, Co is bonded to six equivalent Co and six equivalent Ni atoms to form CoCo6Ni6 cuboctahedra that share corners with twelve CoCo6Ni6 cuboctahedra, edges with twelve CoCo6Ni6 cuboctahedra, edges with twelve equivalent NiCo6Ni6 cuboctahedra, faces with six equivalent CoCo6Ni6 cuboctahedra, and faces with twelve equivalent NiCo6Ni6 cuboctahedra. All Co–Co bond lengths are 2.48 Å. All Co–Ni bond lengths are 2.49 Å. In the second Co site, Co is bonded to six equivalent Co and six Ni atoms to form CoCo6Ni6 cuboctahedra that share corners with five equivalent NiCo6Ni10 cuboctahedra, corners with twelve CoCo6Ni6 cuboctahedra, edges with ten NiCo6Ni6 cuboctahedra, edges with twelve CoCo6Ni6 cuboctahedra, faces with six equivalent CoCo6Ni6 cuboctahedra, and faces with fifteen NiCo6Ni6 cuboctahedra. All Co–Co bond lengths are 2.48 Å. All Co–Ni bond lengths are 2.49 Å. In the third Co site, Co is bonded to six equivalent Co and six Ni atoms to form CoCo6Ni6 cuboctahedra that share corners with five equivalent NiCo6Ni10 cuboctahedra, corners with twelve CoCo6Ni6 cuboctahedra, edges with ten NiCo6Ni6 cuboctahedra, edges with twelve CoCo6Ni6 cuboctahedra, faces with six equivalent CoCo6Ni6 cuboctahedra, and faces with fifteen NiCo6Ni6 cuboctahedra. All Co–Co bond lengths are 2.48 Å. All Co–Ni bond lengths are 2.49 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to six Co and six equivalent Ni atoms to form NiCo6Ni6 cuboctahedra that share corners with twelve NiCo6Ni6 cuboctahedra, edges with twelve CoCo6Ni6 cuboctahedra, edges with twelve NiCo6Ni6 cuboctahedra, faces with six equivalent NiCo6Ni6 cuboctahedra, and faces with twelve CoCo6Ni6 cuboctahedra. All Ni–Ni bond lengths are 2.48 Å. In the second Ni site, Ni is bonded to six Co and ten equivalent Ni atoms to form NiCo6Ni10 cuboctahedra that share corners with ten CoCo6Ni6 cuboctahedra, corners with twelve NiCo6Ni6 cuboctahedra, edges with eight CoCo6Ni6 cuboctahedra, edges with sixteen NiCo6Ni6 cuboctahedra, faces with sixteen equivalent NiCo6Ni10 cuboctahedra, and faces with eighteen CoCo6Ni6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.48–4.96 Å.