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Li W, Shahbazi M, Xing K, Tesfamichael T, Motta N, Qi DC. Highly Sensitive NO2 Gas Sensors Based on MoS2@MoO3 Magnetic Heterostructure. NANOMATERIALS 2022; 12:nano12081303. [PMID: 35458010 PMCID: PMC9027905 DOI: 10.3390/nano12081303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 12/16/2022]
Abstract
Recently, two-dimensional (2D) materials and their heterostructures have attracted considerable attention in gas sensing applications. In this work, we synthesized 2D MoS2@MoO3 heterostructures through post-sulfurization of α-MoO3 nanoribbons grown via vapor phase transport (VPT) and demonstrated highly sensitive NO2 gas sensors based on the hybrid heterostructures. The morphological, structural, and compositional properties of the MoS2@MoO3 hybrids were studied by a combination of advanced characterization techniques revealing a core-shell structure with the coexistence of 2H-MoS2 multilayers and intermediate molybdenum oxysulfides on the surface of α-MoO3. The MoS2@MoO3 hybrids also exhibit room-temperature ferromagnetism, revealed by vibrating sample magnetometry (VSM), as a result of the sulfurization process. The MoS2@MoO3 gas sensors display a p-type-like response towards NO2 with a detection limit of 0.15 ppm at a working temperature of 125 °C, as well as superb selectivity and reversibility. This p-type-like sensing behavior is attributed to the heterointerface of MoS2-MoO3 where interfacial charge transfer leads to a p-type inversion layer in MoS2, and is enhanced by magnetic dipole interactions between the paramagnetic NO2 and the ferromagnetic sensing layer. Our study demonstrates the promising application of 2D molybdenum hybrid compounds in gas sensing applications with a unique combination of electronic and magnetic properties.
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Affiliation(s)
- Wei Li
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia; (W.L.); (M.S.)
- Centre for Materials Science, Queensland University of Technology, Brisbane, QLD 4001, Australia
| | - Mahboobeh Shahbazi
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia; (W.L.); (M.S.)
| | - Kaijian Xing
- School of Physics and Astronomy, Monash University, Clayton, VIC 3800, Australia;
| | - Tuquabo Tesfamichael
- Centre for Materials Science, Queensland University of Technology, Brisbane, QLD 4001, Australia
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Correspondence: (T.T.); (N.M.); (D.-C.Q.)
| | - Nunzio Motta
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia; (W.L.); (M.S.)
- Centre for Materials Science, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Correspondence: (T.T.); (N.M.); (D.-C.Q.)
| | - Dong-Chen Qi
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia; (W.L.); (M.S.)
- Centre for Materials Science, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Correspondence: (T.T.); (N.M.); (D.-C.Q.)
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Chi X, Huang Z, Asmara TC, Han K, Yin X, Yu X, Diao C, Yang M, Schmidt D, Yang P, Trevisanutto PE, Whitcher TJ, Venkatesan T, Breese MBH, Rusydi A. Large Enhancement of 2D Electron Gases Mobility Induced by Interfacial Localized Electron Screening Effect. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1707428. [PMID: 29667241 DOI: 10.1002/adma.201707428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/13/2018] [Indexed: 06/08/2023]
Abstract
The interactions between delocalized and localized charges play important roles in correlated electron systems. Here, using a combination of transport measurements, spectroscopic ellipsometry (SE), and X-ray absorption spectroscopy (XAS) supported by theoretical calculations, we reveal the important role of interfacial localized charges and their screening effects in determining the mobility of (La0.3 Sr0.7 )(Al0.65 Ta0.35 )O3 /SrTiO3 (LSAT/SrTiO3 ) interfaces. When the LSAT layer thickness reaches the critical value of 5 uc, the insulating interface abruptly becomes conducting, accompanied by the appearance of a new midgap state. This midgap state emerges at ≈1 eV below the Ti t2g band and shows a strong character of Ti 3dxy - O 2p hybridization. Increasing the LSAT layer from 5 to 18 uc, the number of localized charges increases, resulting in an enhanced screening effect and higher mobile electron mobility. This observation contradicts the traditional semiconductor interface where the localized charges always suppress the carrier mobility. These results demonstrate a new strategy to probe localized charges and mobile electrons in correlated electronic systems and highlight the important role of screening effects from localized charges in improving the mobile electron mobility at complex oxide interfaces.
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Affiliation(s)
- Xiao Chi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhen Huang
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Teguh C Asmara
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Kun Han
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Xinmao Yin
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Caozheng Diao
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ming Yang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
- Institute of Materials Research and Engineering, A*-STAR, 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Daniel Schmidt
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Paolo E Trevisanutto
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - T J Whitcher
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - T Venkatesan
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore, 117456, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Mark B H Breese
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Andrivo Rusydi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore, 117456, Singapore
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Sarkar TP, Gopinadhan K, Motapothula M, Saha S, Huang Z, Dhar S, Patra A, Lu WM, Telesio F, Pallecchi I, Ariando, Marré D, Venkatesan T. Unexpected observation of spatially separated Kondo scattering and ferromagnetism in Ta alloyed anatase TiO2 thin films. Sci Rep 2015; 5:13011. [PMID: 26265554 PMCID: PMC4533010 DOI: 10.1038/srep13011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 07/08/2015] [Indexed: 11/25/2022] Open
Abstract
We report the observation of spatially separated Kondo scattering and ferromagnetism in anatase Ta0.06Ti0.94O2 thin films as a function of thickness (10–200 nm). The Kondo behavior observed in thicker films is suppressed on decreasing thickness and vanishes below ~25 nm. In 200 nm film, transport data could be fitted to a renormalization group theory for Kondo scattering though the carrier density in this system is lower by two orders of magnitude, the magnetic entity concentration is larger by a similar magnitude and there is strong electronic correlation compared to a conventional system such as Cu with magnetic impurities. However, ferromagnetism is observed at all thicknesses with magnetic moment per unit thickness decreasing beyond 10 nm film thickness. The simultaneous presence of Kondo and ferromagnetism is explained by the spatial variation of defects from the interface to surface which results in a dominantly ferromagnetic region closer to substrate-film interface while the Kondo scattering is dominant near the surface and decreasing towards the interface. This material system enables us to study the effect of neighboring presence of two competing magnetic phenomena and the possibility for tuning them.
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Affiliation(s)
- T P Sarkar
- 1] Department of Physics, National University of Singapore, Singapore 117542 [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - K Gopinadhan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - M Motapothula
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - S Saha
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - Z Huang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - S Dhar
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - A Patra
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - W M Lu
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - F Telesio
- CNR-SPIN and Università di Genova, Dipartimento di Fisica via Dodecaneso 33, Genova Italy 16146
| | - I Pallecchi
- CNR-SPIN and Università di Genova, Dipartimento di Fisica via Dodecaneso 33, Genova Italy 16146
| | - Ariando
- 1] Department of Physics, National University of Singapore, Singapore 117542 [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117576
| | - D Marré
- CNR-SPIN and Università di Genova, Dipartimento di Fisica via Dodecaneso 33, Genova Italy 16146
| | - T Venkatesan
- 1] Department of Physics, National University of Singapore, Singapore 117542 [2] NUSNNI-NanoCore, National University of Singapore, Singapore 117576 [3] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576
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