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Das A, Partyka-Jankowska E, Zając M, Hemberg A, Bittencourt C. Impact of Synthesis Parameters upon the Electronic Structure in PVD-Deposited Cd xZn 1-xO Composite Thin Films: An XPS-XANES Investigation. ACS Omega 2024; 9:9835-9846. [PMID: 38434883 PMCID: PMC10905695 DOI: 10.1021/acsomega.4c00892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 02/02/2024] [Indexed: 03/05/2024]
Abstract
The impact of different synthesis parameters, such as thickness, postsynthesis annealing temperature, and oxygen gas flow rate, upon the electronic structure is discussed in detail in the present experimental investigation. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectroscopy techniques are used to evaluate the surface electronic properties along with the presence and stability of the CdO2 surface oxide in CdxZn1-xO (x = 0.4) composite thin films. The thin films were synthesized with varying thicknesses using a Cd0.4Zn0.6O (CZO) ceramic and Cd0.4Zn0.6 (CZ) metallic targets and oxygen gas flow rates during magnetron sputtering. The Zn L3,2 edge and O K edge XANES spectra are affected by the oxygen gas flow rate. For the zero rate, an increase in intensity is observed in the Zn L3,2 edge, and notable changes occur in the overall spectral features of the O K edge. In the films synthesized in the presence of oxygen, highly probable O 2p → antibonding Zn 3d electronic transitions decrease the probability of the Zn 2p1/2 → antibonding Zn 3d electronic transition by filling the vacant antibonding Zn 3d states, leading to the reduction in overall intensity in the Zn L3,2 edge. Scanning electron microscopy reveals grain growth with increasing annealing temperature. The annealing induces orbital hybridization, generating new electronic states with higher transition probabilities and intensity enhancement in both Zn L3,2 and O K edges. The presence of the CdO2 surface phase is confirmed by analyzing the Cd 3d5/2 and O 1s XPS core levels. The CdO2 surface phase is observed in the films synthesized using the CZO target for all thicknesses, while the CZ target is only observed for higher thicknesses. Further postsynthesis annealing treatment results in the disappearance of the CdO2 phase. The CdO2 surface phase can be controlled by varying the film thickness and postsynthesis annealing temperature.
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Affiliation(s)
- Arkaprava Das
- Chimie des Interaction
Plasma Surface, University of Mons, Place du Parc 23, 7000 Mons, Belgium
| | - Ewa Partyka-Jankowska
- SOLARIS National Synchrotron
Radiation Centre, Jagiellonian University, Czerwone Maki 98, 31-007 Krakow, Poland
| | - Marcin Zając
- SOLARIS National Synchrotron
Radiation Centre, Jagiellonian University, Czerwone Maki 98, 31-007 Krakow, Poland
| | - Axel Hemberg
- Materia Nova, Nicolas Copernic 3, 7000 Mons, Belgium
| | - Carla Bittencourt
- Chimie des Interaction
Plasma Surface, University of Mons, Place du Parc 23, 7000 Mons, Belgium
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Swain A, Das A N, Chandran S, Basu JK. Kinetics of high density functional polymer nanocomposite formation by tuning enthalpic and entropic barriers. Soft Matter 2022; 18:1005-1012. [PMID: 35018946 DOI: 10.1039/d1sm01681d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
High density functional polymer nanocomposites (PNCs) with high degree of dispersion have recently emerged as novel materials for various thermo-mechanical, optical and electrical applications. The key challenge is to attain a high loading while maintaining reasonable dispersion to attain maximum possible benefits from the functional nanoparticle additives. Here, we report a facile method to prepare polymer grafted nanoparticle (PGNP)-based high density functional polymer nanocomposites using thermal activation of a high density PGNP monolayer to overcome entropic or enthalpic barriers to insertion of PGNPs into the underlying polymer films. We monitor the temperature-dependent kinetics of penetration of a high density PGNP layer and correlate the penetration time to the effective enthalpic/entropic barriers. The experimental results are corroborated by coarse-grained molecular dynamics simulations. Repeated application of the methodology to insert nanoparticles by appropriate control over temperature, time and graft-chain properties can lead to enhanced densities of loading in the PNC. Our method can be engineered to produce a wide range of high density polymer nanocomposite membranes for various possible applications including gas separation and water desalination.
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Affiliation(s)
- Aparna Swain
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
| | - Nimmi Das A
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
- Department Physik, Universität Siegen, Walter-Flex-Strasse 3, 57072 Siegen, Germany
- Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Sivasurender Chandran
- Department of Physics, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
| | - J K Basu
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
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Abstract
A Cd-MOF with a one-dimensional cavity can be used as a multifunctional fluorescent probe to effectively recognize CrO42− and Cr2O72− ions, Fe3+ ions and TNP molecules.
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Affiliation(s)
- Lu Liu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials; School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, China
| | - Yuejiao Jia
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials; School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, China
| | - Chen
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials; School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, China
| | - Dechao Li
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials; School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, China
| | - Ming Hu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials; School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, China
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Zhang W, Ji W. Two-dimensional van der Waals heterostructure CdO/PtSe 2: promising visible light photocatalyst for overall water splitting. Phys Chem Chem Phys 2020; 22:24662-24668. [PMID: 33099592 DOI: 10.1039/d0cp03564e] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Due to the gradual depletion of fossil fuels and the serious environmental pollution, hydrogen generation by photocatalytic water splitting has been considered as an alternative strategy for clean energy. Herein, using hybrid density functional calculations, we systematically study the structural, electronic and optical properties of van der Waals heterostructure CdO/PtSe2 with different stacking patterns. The heterostructure is found to be dynamically stable, and has type-II band alignment with a large built-in electric field, which is favorable for the efficient spatial separation of photogenerated charge carriers. By revealing the intrinsic interface dipoles dependent photocatalytic mechanisms, we find the band edges of all patterns straddle the water redox levels despite the AB-1 pattern having a bandgap less than 1.23 eV. Moreover, the heterostructure shows globally improved optical absorptions with a large absorption coefficient (105 cm-1) compared to the single layers, demonstrating the enhanced photocatalytic activity. Comparing with widely discussed bilayer systems like graphene/C3N4 and MoS2/C3N4, the CdO/PtSe2 simultaneously has several advantages or peculiarities such as the more favorable absorption of visible light, therefore CdO/PtSe2 is a promising candidate and a unique system for photocatalytic water splitting.
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Affiliation(s)
- Wei Zhang
- Physicochemical Group of College of Criminal Science and Technology & Forensic Center of Public Security of Bureau of National Forestry Bureau, Nanjing Forest Police College, Nanjing 210023, China.
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Kumar P, Mathpal MC, Inwati GK, Ghosh S, Kumar V, Roos WD, Swart HC. Optical and surface properties of Zn doped CdO nanorods and antimicrobial applications. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125369] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Swain A, Begam N, Chandran S, Bobji MS, Basu JK. Engineering interfacial entropic effects to generate giant viscosity changes in nanoparticle embedded polymer thin films. Soft Matter 2020; 16:4065-4073. [PMID: 32286599 DOI: 10.1039/d0sm00019a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Thin polymer and polymer nanocomposite (PNC) films are being extensively used as advanced functional coating materials in various technological applications. Since it is widely known that various properties of these thin films, especially their thermo-mechanical behavior, can be considerably different from the bulk depending on the thickness as well as interaction with surrounding media, it is imperative to study these properties directly on the films. However, quite often, it becomes difficult to perform these measurements reliably due to a dearth of techniques, especially to measure mechnical or transport properties like the viscosity of thin polymer or PNC films. Here, we demonstrate a new method to study the viscosity of PNC thin films using atomic force microscopy based force-distance spectroscopy. Using this method we investigated viscosity and the glass transition, Tg, of PNC thin films consisting of polymer grafted nanoparticles (PGNPs) embedded in un-entangled homopolymer melt films. The PGNP-polymer interfacial entropic interaction parameter, f, operationally controlled through the ratio of grafted and matrix molecular weight, was systematically tuned while maintaining good dispersion even at very high PGNP loadings, φ. We observed both a significant reduction (low f) and giant enhancement (high f) in the viscosity of the PNC thin films with the effect becoming more prominent with increasing φ. Significantly, none of the established theoretical models for viscosity changes observed earlier in suspensions or polymer nanocomposites can explain the observed viscosity variation. Our results thus not only demonstrate the tunability of the interfacial entropic effect to facilitate a dramatic change in the viscosity of PNC coatings, which could be of great utility in various applications of these materials, but also suggest a new regime of viscosity variation in athermal PNC films indicating the possible need for a new theoretical model.
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Affiliation(s)
- Aparna Swain
- Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Nafisa Begam
- Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | | | - M S Bobji
- Indian Institute of Science, Department of Mechanical Engineering, Indian Institute of Science, Bangalore, 560012, India
| | - J K Basu
- Department of Physics, Indian Institute of Science, Bangalore 560012, India.
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