1
|
Lin PC, Villarreal R, Achilli S, Bana H, Nair MN, Tejeda A, Verguts K, De Gendt S, Auge M, Hofsäss H, De Feyter S, Di Santo G, Petaccia L, Brems S, Fratesi G, Pereira LMC. Doping Graphene with Substitutional Mn. ACS NANO 2021; 15:5449-5458. [PMID: 33596385 DOI: 10.1021/acsnano.1c00139] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report the incorporation of substitutional Mn atoms in high-quality, epitaxial graphene on Cu(111), using ultralow-energy ion implantation. We characterize in detail the atomic structure of substitutional Mn in a single carbon vacancy and quantify its concentration. In particular, we are able to determine the position of substitutional Mn atoms with respect to the Moiré superstructure (i.e., local graphene-Cu stacking symmetry) and to the carbon sublattice; in the out-of-plane direction, substitutional Mn atoms are found to be slightly displaced toward the Cu surface, that is, effectively underneath the graphene layer. Regarding electronic properties, we show that graphene doped with substitutional Mn to a concentration of the order of 0.04%, with negligible structural disorder (other than the Mn substitution), retains the Dirac-like band structure of pristine graphene on Cu(111), making it an ideal system in which to study the interplay between local magnetic moments and Dirac electrons. Our work also establishes that ultralow-energy ion implantation is suited for substitutional magnetic doping of graphene. Given the flexibility, reproducibility, and scalability inherent to ion implantation, our work creates numerous opportunities for research on magnetic functionalization of graphene and other two-dimensional materials.
Collapse
Affiliation(s)
- Pin-Cheng Lin
- Quantum Solid State Physics, KU Leuven, 3001 Leuven, Belgium
| | | | - Simona Achilli
- ETSF and Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, Via Celoria, 16, I-20133 Milano, Italy
| | - Harsh Bana
- Quantum Solid State Physics, KU Leuven, 3001 Leuven, Belgium
| | - Maya N Nair
- CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, New York 10031, United States
| | - Antonio Tejeda
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, 91405 Orsay, France
| | - Ken Verguts
- imec vzw, 3001 Leuven, Belgium
- Department of Chemistry, Division of Molecular Design and Synthesis, KU Leuven, 3001 Leuven, Belgium
| | - Stefan De Gendt
- imec vzw, 3001 Leuven, Belgium
- Department of Chemistry, Division of Molecular Design and Synthesis, KU Leuven, 3001 Leuven, Belgium
| | - Manuel Auge
- II.Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Hans Hofsäss
- II.Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Steven De Feyter
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, 3001 Leuven, Belgium
| | - Giovanni Di Santo
- Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149 Trieste, Italy
| | - Luca Petaccia
- Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149 Trieste, Italy
| | | | - Guido Fratesi
- ETSF and Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, Via Celoria, 16, I-20133 Milano, Italy
| | | |
Collapse
|
2
|
Organic Spintronics: A Theoretical Investigation of a Graphene-Porphyrin Based Nanodevice. MAGNETOCHEMISTRY 2020. [DOI: 10.3390/magnetochemistry6020027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Spintronics is one of the most exciting applications of graphene-based devices. In this work Density Functional Theory is used to study a nanojunction consisting of two semi-infinite graphene electrodes contacted with an iron-porphyrin (FeP) molecule, which plays the role of spin filter for the incoming unpolarized electrons. The graphene-FeP contact closely resembles the recently synthesized porphyrin-decorated graphene [He et al., Nat. Chem. 2017, 9, 33–38]. The analysis of the spectral properties of the system shows a variation of the orbital occupancy with respect to the isolated FeP molecule and an hybridization with the delocalized states of the substrate, while the overall magnetic moment remains unchanged. Doping the electrodes with boron or nitrogen atoms induces a relevant rearrangement in the electronic structure of the junction. Upon B doping the current becomes significantly spin polarized, while N doping induces a marked Negative Differential Resistivity effect. We have also investigated the possible exploitation of the FeP junction as a gas sensor device. We demonstrate that the interaction of CO and O2 molecules with the Fe atom, while being strong enough to be stable at room temperature (2.0 eV and 1.1 eV, respectively), induces only minor effects on the electronic properties of the junction. Interestingly, a quenching of the spin polarization of the current is observed in the B-doped system.
Collapse
|
3
|
Liang S, Zhu C, Zhang N, Zhang S, Qiao B, Liu H, Liu X, Liu Z, Song X, Zhang H, Hao C, Shi Y. A Novel Single-Atom Electrocatalyst Ti 1 /rGO for Efficient Cathodic Reduction in Hybrid Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2000478. [PMID: 32250020 DOI: 10.1002/adma.202000478] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
Single-atom catalysts (SACs) are a frontier research topic in the catalysis community. Carbon materials decorated with atomically dispersed Ti are theoretically predicted with many attractive applications. However, such material has not been achieved so far. Herein, a Ti-based SAC, consisting of isolated Ti anchored by oxygen atoms on reduced graphene oxide (rGO) (termed as Ti1 /rGO), is successfully synthesized. The structure of Ti1 /rGO is characterized by high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy, being determined to have a five coordinated local structure TiO5 . When serving as non-Pt cathode material in dye-sensitized solar cells (DSCs), Ti1 /rGO exhibits high electrocatalytic activity toward the tri-iodide reduction reaction. The power conversion efficiency of DSCs based on Ti1 /rGO is comparable to that using conventional Pt cathode. The unique structure of TiO5 moieties and the crucial role of atomically dispersed Ti in Ti1 /rGO are well understood by experiments and density functional theory calculations. This emerging material shows potential applications in energy conversion and storage devices.
Collapse
Affiliation(s)
- Suxia Liang
- State Key Laboratory of Fine Chemicals, Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Naitian Zhang
- State Key Laboratory of Fine Chemicals, Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China
| | - Shuo Zhang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China
| | - Botao Qiao
- Laboratory of Aerospace Catalysis and New Materials, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, 116023, China
| | - Hua Liu
- Laboratory of Aerospace Catalysis and New Materials, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, 116023, China
| | - Xiaoyan Liu
- Laboratory of Aerospace Catalysis and New Materials, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, 116023, China
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Environmental Chemistry and Materials Centre, Nanyang Environment and Water Research Institute, Singapore, Singapore
- CINTRA CNRS/NTU/THALSE, UMI 3288, Research Techno Plaza, Singapore, Singapore
| | - Xuedan Song
- State Key Laboratory of Fine Chemicals, Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China
| | - Heming Zhang
- State Key Laboratory of Fine Chemicals, Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China
| | - Ce Hao
- State Key Laboratory of Fine Chemicals, Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China
| | - Yantao Shi
- State Key Laboratory of Fine Chemicals, Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China
| |
Collapse
|
4
|
Bragato M, Achilli S, Cargnoni F, Ceresoli D, Martinazzo R, Soave R, Trioni MI. Magnetic Moments and Electron Transport through Chromium-Based Antiferromagnetic Nanojunctions. MATERIALS (BASEL, SWITZERLAND) 2018; 11:E2030. [PMID: 30340431 PMCID: PMC6213584 DOI: 10.3390/ma11102030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/20/2018] [Accepted: 10/17/2018] [Indexed: 11/16/2022]
Abstract
We report the electronic, magnetic and transport properties of a prototypical antiferromagnetic (AFM) spintronic device. We chose Cr as the active layer because it is the only room-temperature AFM elemental metal. We sandwiched Cr between two non-magnetic metals (Pt or Au) with large spin-orbit coupling. We also inserted a buffer layer of insulating MgO to mimic the structure and finite resistivity of a real device. We found that, while spin-orbit has a negligible effect on the current flowing through the device, the MgO layer plays a crucial role. Its effect is to decouple the Cr magnetic moment from Pt (or Au) and to develop an overall spin magnetization. We have also calculated the spin-polarized ballistic conductance of the device within the Büttiker⁻Landauer framework, and we have found that for small applied bias our Pt/Cr/MgO/Pt device presents a spin polarization of the current amounting to ≃25%.
Collapse
Affiliation(s)
- Marco Bragato
- Department of Chemistry, University of Milan, 20133 Milan, Italy.
| | - Simona Achilli
- Department of Physics, University of Milan, 20133 Milan, Italy.
| | - Fausto Cargnoni
- Consiglio Nazionale delle Ricerche, Istituto di Scienze e Tecnologie Molecolari and INSTM UdR di Milano, via Golgi 19, 20133 Milan, Italy.
| | - Davide Ceresoli
- Consiglio Nazionale delle Ricerche, Istituto di Scienze e Tecnologie Molecolari and INSTM UdR di Milano, via Golgi 19, 20133 Milan, Italy.
| | - Rocco Martinazzo
- Department of Chemistry, University of Milan, 20133 Milan, Italy.
| | - Raffaella Soave
- Consiglio Nazionale delle Ricerche, Istituto di Scienze e Tecnologie Molecolari and INSTM UdR di Milano, via Golgi 19, 20133 Milan, Italy.
| | - Mario Italo Trioni
- Consiglio Nazionale delle Ricerche, Istituto di Scienze e Tecnologie Molecolari and INSTM UdR di Milano, via Golgi 19, 20133 Milan, Italy.
| |
Collapse
|