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Diao Y, Zhang Y, Li Y, Jiang J. Metal-Oxide Heterojunction: From Material Process to Neuromorphic Applications. SENSORS (BASEL, SWITZERLAND) 2023; 23:9779. [PMID: 38139625 PMCID: PMC10747618 DOI: 10.3390/s23249779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 11/30/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023]
Abstract
As technologies like the Internet, artificial intelligence, and big data evolve at a rapid pace, computer architecture is transitioning from compute-intensive to memory-intensive. However, traditional von Neumann architectures encounter bottlenecks in addressing modern computational challenges. The emulation of the behaviors of a synapse at the device level by ionic/electronic devices has shown promising potential in future neural-inspired and compact artificial intelligence systems. To address these issues, this review thoroughly investigates the recent progress in metal-oxide heterostructures for neuromorphic applications. These heterostructures not only offer low power consumption and high stability but also possess optimized electrical characteristics via interface engineering. The paper first outlines various synthesis methods for metal oxides and then summarizes the neuromorphic devices using these materials and their heterostructures. More importantly, we review the emerging multifunctional applications, including neuromorphic vision, touch, and pain systems. Finally, we summarize the future prospects of neuromorphic devices with metal-oxide heterostructures and list the current challenges while offering potential solutions. This review provides insights into the design and construction of metal-oxide devices and their applications for neuromorphic systems.
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Affiliation(s)
| | | | | | - Jie Jiang
- Hunan Key Laboratory of Nanophotonics and Devices, School of Physics, Central South University, 932 South Lushan Road, Changsha 410083, China
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2
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Dhimba G, Muller A, Lammertsma K. Chiral-at-Metal Racemization Unraveled for MX 2 (a-chel) 2 by means of a Computational Analysis of MoO 2 (acnac) 2. Chemistry 2023; 29:e202302516. [PMID: 37730887 DOI: 10.1002/chem.202302516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 09/22/2023]
Abstract
Octahedral chiral-at-metal complexes MX2 (a-chel)2 (a-chel=asymmetric chelate) can rearrange their ligands by four mechanisms known as the Bailar (B), Ray-Dutt (RD), Conte-Hippler (CH), and Dhimba-Muller-Lammertsma (DML) twists. Racemization involves their interconnections, which were computed for MoO2 (acnac)2 (acnac=β-ketoiminate) using density functional theory at ωB97x-D with the 6-31G(d,p) and 6-311G(2d,p) basis sets and LANL2DZ for molybdenum. Racemizing the cis(NN) isomer, being the global energy minimum with trans oriented imine groups, is a three step process (DML-CH-DML) that requires 17.4 kcal/mol, while all three cis isomers (cis(NN), cis(NO), and cis(OO)) interconvert at ≤17.9 kcal/mol. The B and RD twists are energetically not competitive and neither are the trans isomers. The interconnection of all enantiomeric minima and transition structures is summarized in a graph that also visualizes valley ridge inflection points for two of the three CH twists. Geometrical features of the minima and twists are given. Lastly, the influence of N-substitution on the favored racemization pathway is evaluated. The present comprehensive study serves as a template for designing chiral-at-metal MX2 (a-chel)2 catalysts that may retain their chiral integrity.
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Affiliation(s)
- George Dhimba
- Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa
| | - Alfred Muller
- Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa
| | - Koop Lammertsma
- Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa
- Department of Chemistry and Pharmaceutical Sciences, Faculty of Sciences Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
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Shaw TE, Ali Z, Currie TM, Berriel SN, Butkus B, Wagner JT, Preradovic K, Yap GPA, Green JC, Banerjee P, Sattelberger AP, McElwee-White L, Jurca T. Molybdenum(III) Amidinate: Synthesis, Characterization, and Vapor Phase Growth of Mo-Based Materials. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37450887 DOI: 10.1021/acsami.3c04074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
The synthesis, characterization, and thermogravimetric analysis of tris(N,N'-di-isopropylacetamidinate)molybdenum(III), Mo(iPr-AMD)3, are reported. Mo(iPr-AMD)3 is a rare example of a homoleptic mononuclear complex of molybdenum(III) and fills a longstanding gap in the literature of transition metal(III) trisamidinate complexes. Thermogravimetric analysis (TGA) reveals excellent volatilization at elevated temperatures, pointing to potential applications as a vapor phase precursor for higher temperature atomic layer deposition (ALD), or chemical vapor deposition (CVD) growth of Mo-based materials. The measured TGA temperature window was 200-314 °C for samples in the 3-20 mg range. To validate the utility of Mo(iPr-AMD)3, we demonstrate aerosol-assisted CVD growth of MoO3 from benzonitrile solutions of Mo(iPr-AMD)3 at 500 °C using compressed air as the carrier gas. The resulting films are characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. We further demonstrate the potential for ALD growth at 200 °C with a Mo(iPr-AMD)3/Ar purge/300 W O2 plasma/Ar purge sequence, yielding ultrathin films which retain a nitride/oxynitride component. Our results highlight the broad scope utility and potential of Mo(iPr-AMD)3 as a stable, high-temperature precursor for both CVD and ALD processes.
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Affiliation(s)
- Thomas E Shaw
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
- Renewable Energy and Chemical Transformations Cluster, University of Central Florida, Orlando, Florida 32816, United States
| | - Zahra Ali
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Taylor M Currie
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - S Novia Berriel
- Renewable Energy and Chemical Transformations Cluster, University of Central Florida, Orlando, Florida 32816, United States
- Department of Materials Science & Engineering, University of Central Florida, Orlando, Florida 32816, United States
| | - Brian Butkus
- Department of Materials Science & Engineering, University of Central Florida, Orlando, Florida 32816, United States
| | - J Tyler Wagner
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Konstantin Preradovic
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Glenn P A Yap
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Jennifer C Green
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, U.K
| | - Parag Banerjee
- Renewable Energy and Chemical Transformations Cluster, University of Central Florida, Orlando, Florida 32816, United States
- Department of Materials Science & Engineering, University of Central Florida, Orlando, Florida 32816, United States
- NanoScience & Technology Center, University of Central Florida, Orlando, Florida 32826, United States
| | - Alfred P Sattelberger
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
- NanoScience & Technology Center, University of Central Florida, Orlando, Florida 32826, United States
| | - Lisa McElwee-White
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Titel Jurca
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
- Renewable Energy and Chemical Transformations Cluster, University of Central Florida, Orlando, Florida 32816, United States
- NanoScience & Technology Center, University of Central Florida, Orlando, Florida 32826, United States
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Guaiacol to Aromatics: Efficient Transformation over In Situ-Generated Molybdenum and Tungsten Oxides. Catalysts 2023. [DOI: 10.3390/catal13020263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The development of catalysts for the hydrodeoxygenation of bio-based feedstocks is an important step towards the production of fuels and chemicals from biomass. This paper describes in situ-generated bulk molybdenum and tungsten oxides in the hydrodeoxygenation of the lignin-derived compound guaiacol. The catalysts obtained were studied using powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transition electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, and Raman spectroscopy. The use of metal carbonyls as precursors was shown to promote the formation of amorphous molybdenum oxide and crystalline tungsten phosphide under hydrodeoxygenation conditions. The catalysts’ activity was investigated under various reaction conditions (temperature, H2 pressure, solvent). MoOx was more active in the partial and full hydrodeoxygenation of guaiacol at temperatures of 200–380 °C (5 MPa H2, 6 h). However, cyclohexane, which is an undesirable product, was formed in significant amounts using MoOx (5 MPa H2, 6 h), while WOx was more selective to aromatics. When using dodecane as a solvent (380 °C, 5 MPa H2, 6 h), the benzene-toluene-xylenes fraction was obtained with a 96% yield over the WOx catalyst.
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Wilken M, Ciftyürek E, Cwik S, Mai L, Mallick B, Rogalla D, Schierbaum K, Devi A. CVD Grown Tungsten Oxide for Low Temperature Hydrogen Sensing: Tuning Surface Characteristics via Materials Processing for Sensing Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2204636. [PMID: 36354167 DOI: 10.1002/smll.202204636] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/04/2022] [Indexed: 06/16/2023]
Abstract
The intrinsic properties of semiconducting oxides having nanostructured morphology are highly appealing for gas sensing. In this study, the fabrication of nanostructured WO3 thin films with promising surface characteristics for hydrogen (H2 ) gas sensing applications is accomplished. This is enabled by developing a chemical vapor deposition (CVD) process employing a new and volatile tungsten precursor bis(diisopropylamido)-bis(tert-butylimido)-tungsten(VI), [W(Nt Bu)2 (Ni Pr2 )2 ]. The as-grown nanostructured WO3 layers are thoroughly analyzed. Particular attention is paid to stoichiometry, surface characteristics, and morphology, all of which strongly influence the gas-sensing potential of WO3 . Synchrotron-based ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), X-ray photoelectron emission microscopy (XPEEM), low-energy electron microscopy (LEEM) and 4-point van der Pauw (vdP) technique made it possible to analyze the surface chemistry and structural uniformity with a spatially resolved insight into the chemical, electronic and electrical properties. The WO3 layer is employed as a hydrogen (H2 ) sensor within interdigitated mini-mobile sensor architecture capable of working using a standard computer's 5 V 1-wirebus connection. The sensor shows remarkable sensitivity toward H2 . The high, robust, and repeatable sensor response (S) is attributed to the homogenous distribution of the W5+ oxidation state and associated oxygen vacancies, as shown by synchrotron-based UPS, XPS, and XPEEM analysis.
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Affiliation(s)
- Martin Wilken
- Inorganic Materials Chemistry, Ruhr University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
| | - Engin Ciftyürek
- Department of Materials Science, Institute for Experimental Condensed Matter Physics, Heinrich-Heine University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Stefan Cwik
- Inorganic Materials Chemistry, Ruhr University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
| | - Lukas Mai
- Inorganic Materials Chemistry, Ruhr University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
| | - Bert Mallick
- Inorganic Chemistry 2, Ruhr University Bochum, 44801, Bochum, Germany
| | - Detlef Rogalla
- RUBION, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Klaus Schierbaum
- Department of Materials Science, Institute for Experimental Condensed Matter Physics, Heinrich-Heine University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Anjana Devi
- Inorganic Materials Chemistry, Ruhr University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
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Tang Y, Wu F, Chen H, Chai JL, Chen XD, Xi B. Facile synthesis of M(=NtBu)2(CH2SiMe3)2 (M = Mo or W) as potential precursors for thin film deposition. INORG CHEM COMMUN 2022. [DOI: 10.1016/j.inoche.2022.110284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Muhammad S, Ferenczy ET, Germaine IM, Wagner JT, Jan MT, McElwee-White L. Molybdenum(IV) dithiocarboxylates as single-source precursors for AACVD of MoS 2 thin films. Dalton Trans 2022; 51:12540-12548. [PMID: 35913376 PMCID: PMC9426634 DOI: 10.1039/d2dt01852g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tetrakis(dithiocarboxylato)molybdenum(IV) complexes of the type Mo(S2CR)4 (R = Me, Et, iPr, Ph) were synthesized, characterized, and prescreened as precursors for aerosol assisted chemical vapor deposition (AACVD) of MoS2 thin films. The thermal behavior of the complexes as determined by TGA and GC-MS was appropriate for AACVD, although the complexes were not sufficiently volatile for conventional CVD bubbler systems. Thin films of MoS2 were grown by AACVD at 500 °C from solutions of Mo(S2CMe)4 in toluene. The films were characterized by GIXRD diffraction patterns which correspond to a 2H-MoS2 structure in the deposited film. Mo-S bonding in 2H-MoS2 was further confirmed by XPS and EDS. The film morphology, vertically oriented structure, and thickness (2.54 μm) were evaluated by FE-SEM. The Raman E12g and A1g vibrational modes of crystalline 2H-MoS2 were observed. These results demonstrate the use of dithiocarboxylato ligands for the chemical vapor deposition of metal sulfides.
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Affiliation(s)
- Saleh Muhammad
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
- Department of Chemistry, Islamia College Peshawar, 25120 Peshawar, Pakistan
| | - Erik T Ferenczy
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
| | - Ian M Germaine
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
| | - J Tyler Wagner
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
| | - Muhammad T Jan
- Department of Chemistry, Islamia College Peshawar, 25120 Peshawar, Pakistan
| | - Lisa McElwee-White
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
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Ethyl zinc 𝛽‐ketoiminates and 𝛽‐amidoenoates: The influence of precursor design on the deposition of highly conductive zinc oxide thin films via AACVD. Chempluschem 2022; 87:e202100537. [DOI: 10.1002/cplu.202100537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/26/2022] [Indexed: 11/07/2022]
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