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Roy KS, Subramaniam C, Panchakarla LS. Non-Stoichiometry Induced Exsolution of Metal Oxide Nanoparticles via Formation of Wavy Surfaces and their Enhanced Electrocatalytic Activity: Case of Misfit Calcium Cobalt Oxide. ACS APPLIED MATERIALS & INTERFACES 2021; 13:9897-9907. [PMID: 33591175 DOI: 10.1021/acsami.0c20891] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Most heterogeneous catalytic reactions demand high density and yet spatially separated nanoparticles that are strongly anchored on the oxide surfaces. Such nanoparticles can be deposited or synthesized in situ via nonstoichiometric methods. To date, nanoparticles have been exsolved from perovskite oxide surfaces using nonstoichiometric processes. However, the density of the space-separated nanoparticles on the oxide surfaces is still low. And less attention is paid toward the changes that happen to the host during the nanoparticle exsolution process. In this work, we demonstrated in situ exsolution of ultrafine nanoparticles (∼5 nm) of either Co3O4 or Ca(OH)2 via judicious control of nonstoichiometry in a misfit Ca3Co4O9 (CCO). The nanoparticle density over the CCO surface reached as high as 8500/μm2, which is significantly higher than previously reported values. High-resolution electron microscopy studies reveal the formation mechanism of Co3O4 nanoparticles over CCO, and the formation takes palace via the formation of wavy surfaces on the CCO. Defects caused by the nonstoichiometric synthesis created microstrain within the host CCO, resulting in making the new density of states near the Fermi energy. Further, the exsolution process turned the inert host (CCO) into electrocatalytically active toward water splitting. The nonstoichiometric samples obtained by shorter annealing times showed high electrocatalytic behavior for the hydrogen evolution (HER) and oxygen evolution (OER) reactions. The catalytic activity is further enhanced (reaching overpotential of 320 mV and 410 mV for HER and OER respectively, for a current density of 10 mA/cm2) by removing the surface nanoparticles. The observation indicates that the active sites that are produced during the nonstoichiometric synthesis also present in the bulk of the CCO (host). We believe that similar nonstoichiometric synthesis can be applied to a wide variety of tricomponent systems, and they could endow the hosts with novel properties for applications such as catalysis and thermoelectrics.
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Affiliation(s)
- Kankona Singha Roy
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | | | - Leela S Panchakarla
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Selectivity in UV photocatalytic CO2 conversion over bare and silver-decorated niobium-tantalum perovskites. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.01.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Multiferroic and Optical Properties of La0.05Li0.85NbO3 and LiNbO3 Nanocrystals. JOURNAL OF NANOTECHNOLOGY 2018. [DOI: 10.1155/2018/3721095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The chemistry and physics of surfaces is an increasingly important subject. The study of surfaces is the key of many important nanotechnological applications due to the understanding of phase transitions, electronic structure, and chemical bonding. In later years, exotic phenomena that jointly involve the magnetic and electrical conductivity properties have been discovered in oxides that contain magnetic ions. Moreover, the uses of magnetic oxides in electronic technology have become so important due to the miniaturization of devices and magnetic materials with dielectric properties or vice versa being required for inductors, information storage, thin films for high-density computer memories, microwave antireflection coatings, and permanent magnets for automobile ignitions among others. On the contrary, nanotechnology developments over 10 years or so have provided intensive studies in trying to combine properties such as ferroelectric, ferromagnetic, and optics in one single-phase nanoparticles or in composite thin films; this last effort has been recently known as multiferroic. Because of this, the resurgence of nanomaterials with multiferroic and optical properties is presented in this work of one single phase in lanthanum lithium niobate (La0.05Li0.85NbO3) and lithium niobate (LiNbO3) with ferromagnetic, ferroelectric, relaxor ferroelectricity, second harmonic generation, high-temperature ferromagnetic, and magnetoelectric properties.
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Sanna S, Schmidt WG. LiNbO 3 surfaces from a microscopic perspective. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:413001. [PMID: 28737161 DOI: 10.1088/1361-648x/aa818d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A large number of oxides has been investigated in the last twenty years as possible new materials for various applications ranging from opto-electronics to heterogeneous catalysis. In this context, ferroelectric oxides are particularly promising. The electric polarization plays a crucial role at many oxide surfaces, and it largely determines their physical and chemical properties. Ferroelectrics offer in addition the possibility to control/switch the electric polarization and hence the surface chemistry, allowing for the realization of domain-engineered nanoscale devices such as molecular detectors or highly efficient catalysts. Lithium niobate (LiNbO3) is a ferroelectric with a high spontaneous polarization, whose surfaces have a huge and largely unexplored potential. Owing to recent advances in experimental techniques and sample preparation, peculiar and exclusive properties of LiNbO3 surfaces could be demonstrated. For example, water films freeze at different temperatures on differently polarized surfaces, and the chemical etching properties of surfaces with opposite polarization are strongly different. More important, the ferroelectric domain orientation affects temperature dependent surface stabilization mechanisms and molecular adsorption phenomena. Various ab initio theoretical investigations have been performed in order to understand the outcome of these experiments and the origin of the exotic behavior of the lithium niobate surfaces. Thanks to these studies, many aspects of their surface physics and chemistry could be clarified. Yet other puzzling features are still not understood. This review gives a résumé on the present knowledge of lithium niobate surfaces, with a particular view on their microscopic properties, explored in recent years by means of ab initio calculations. Relevant aspects and properties of the surfaces that need further investigation are briefly discussed. The review is concluded with an outlook of challenges and potential payoff for LiNbO3 based applications.
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Affiliation(s)
- Simone Sanna
- Institut für Theoretische Physik, Justus-Liebig-Universität Gießen, Gießen, Germany
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Kaur M, Liu Q, Crozier PA, Nemanich RJ. Photochemical Reaction Patterns on Heterostructures of ZnO on Periodically Poled Lithium Niobate. ACS APPLIED MATERIALS & INTERFACES 2016; 8:26365-26373. [PMID: 27603227 DOI: 10.1021/acsami.6b06060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The internal electric field in LiNbO3 provides a driving force for heterogeneous photocatalytic reactions, where photoexcited holes or electrons can participate in redox reactions on positive (+c) and negative (-c) domain surfaces and at the domain boundaries. One method to characterize the surface chemical reactivity is to measure photoinduced Ag deposition by immersing the LiNbO3 in an aqueous AgNO3 solution and illuminating with above bandgap light. Reduction of Ag+ ions leads to the formation of Ag nanoparticles at the surface, and a high density of Ag nanoparticles indicates enhanced surface photochemical reactions. In this study, an n-type semiconducting ZnO layer is deposited on periodically poled LiNbO3 (PPLN) to modulate the surface electronic properties and impact the surface redox reactions. After plasma enhanced atomic layer deposition (PEALD) of 1, 2, 4, and 10 nm ZnO thin films on PPLN substrates, the substrates were immersed in aqueous AgNO3 and illuminated with above band gap UV light. The Ag nanoparticle density increased for 1 and 2 nm ZnO/PPLN heterostructures, indicating an enhanced electron density at the ZnO/PPLN surface. However, increasing the ZnO thickness beyond 2 nm resulted in a decrease in the Ag nanoparticle density. The increase in nanoparticle density is related to the photoexcited charge density at the ZnO/PPLN interface and the presence of a weakly adsorbed Stern layer at the ZnO surface. The decrease in the nanoparticle density for thicker ZnO is attributed to photoexcited electron screening in the ZnO layer that suppresses electron flow from the LiNbO3 to ZnO surface.
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Affiliation(s)
- Manpuneet Kaur
- School for Engineering of Matter, Transport and Energy, Arizona State University , Tempe, Arizona 85287-6106, United States
| | - Qianlang Liu
- School for Engineering of Matter, Transport and Energy, Arizona State University , Tempe, Arizona 85287-6106, United States
| | - Peter A Crozier
- School for Engineering of Matter, Transport and Energy, Arizona State University , Tempe, Arizona 85287-6106, United States
| | - Robert J Nemanich
- Department of Physics, Arizona State University , Tempe, Arizona 85287-1504, United States
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Wu J, Xiao D, Zhu J. Potassium-sodium niobate lead-free piezoelectric materials: past, present, and future of phase boundaries. Chem Rev 2015; 115:2559-95. [PMID: 25792114 DOI: 10.1021/cr5006809] [Citation(s) in RCA: 240] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jiagang Wu
- Department of Materials Science, Sichuan University, Chengdu 610064, China
| | - Dingquan Xiao
- Department of Materials Science, Sichuan University, Chengdu 610064, China
| | - Jianguo Zhu
- Department of Materials Science, Sichuan University, Chengdu 610064, China
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Rao CN, Sagar SB, Harshitha NG, Aepuru R, Premkumar S, Panda HS, Choubey RK, Kale SN. Lithium niobate nanoparticle-coated Y-coupler optical fiber for enhanced electro-optic sensitivity. OPTICS LETTERS 2015; 40:491-494. [PMID: 25680132 DOI: 10.1364/ol.40.000491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single crystals of lithium niobate (LiNbO3), possessing high birefringence and anisotropic properties have been explored, for a long time, to harness their excellent electro-optic properties. However, their nanoforms are comparatively less explored. In this context, dielectric constant and polarization (P) versus electric-field (E) characteristics of LiNbO3 nanomaterials have been studied. A nonideal P-E loop and a dielectric constant of 20 at the onset of 1 kHz were seen. The electro-optic sensitivity was found to be 4 times as compared to the bulk LiNbO3 crystals. The results are attributed to oxygen vacancies, antisite defects, and grain boundary effects in an already congruent structural matrix of LiNbO3.
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Kim Y, Kim SS, Ada E, Yang YL, Jacobson AJ, Rabalais JW. Scattered and recoiled ion fractions from LiTaO3(100) surfaces with different electrical properties. J Chem Phys 1999. [DOI: 10.1063/1.479548] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Dissociative adsorption and subsequent reactions of methane on Ar-ion sputtered single crystal of LiNbO3. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s1381-1169(97)00143-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Tabata K, Kamada M, Choso T, Munakata H. Theoretical Calculations and XPS Studies of the Adsorption of NO on a Single Crystal of LiNbO3. J Phys Chem B 1997. [DOI: 10.1021/jp9711407] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kenji Tabata
- Research Institute of Innovative Technology for the Earth (RITE), Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-02, Japan
| | - Masahiko Kamada
- Research Institute of Innovative Technology for the Earth (RITE), Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-02, Japan
| | - Tetsuo Choso
- Research Institute of Innovative Technology for the Earth (RITE), Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-02, Japan
| | - Hiroaki Munakata
- Research Institute of Innovative Technology for the Earth (RITE), Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-02, Japan
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Morant C, Sanz JM, Galán L. Ar-ion bombardment effects on ZrO2 surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:1391-1398. [PMID: 10001617 DOI: 10.1103/physrevb.45.1391] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Donnerberg H, Tomlinson SM, Catlow CR, Schirmer OF. Computer-simulation studies of intrinsic defects in LiNbO3 crystals. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:11909-11916. [PMID: 9991797 DOI: 10.1103/physrevb.40.11909] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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García-Cabaes A, Sanz-García JA, Cabrera JM, Agulló-López F, Zaldo C, Pareja R, Polgár K, Raksányi K, Fölvàri I. Influence of stoichiometry on defect-related phenomena in LiNbO3. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 37:6085-6091. [PMID: 9943839 DOI: 10.1103/physrevb.37.6085] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Schreck E, Dransfeld K. Enhanced electrical surface conductivity of LiNbO3 induced by argon-ion bombardment. ACTA ACUST UNITED AC 1987. [DOI: 10.1007/bf00616700] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bermudez VM, Hudgens JW, Hoffbauer MA. Detection of iron in lithium niobate by laser-induced fluorescence of sputtered atoms. APPLIED OPTICS 1983; 22:3681-3683. [PMID: 20407525 DOI: 10.1364/ao.22.003681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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