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Amit Khare Dongwon Shin Tae Sup Yoo Minu Kim Tae Dong Kang Jaekwang Lee Seulki Roh In‐Ho Jung Jungseek Hwang Sung Wng Kim Tae Won Noh Hiromichi Ohta Woo Seok Choi 《Advanced materials (Deerfield Beach, Fla.)》2017,29(37)
Topotactic phase transformation enables structural transition without losing the crystalline symmetry of the parental phase and provides an effective platform for elucidating the redox reaction and oxygen diffusion within transition metal oxides. In addition, it enables tuning of the emergent physical properties of complex oxides, through strong interaction between the lattice and electronic degrees of freedom. In this communication, the electronic structure evolution of SrFeOx epitaxial thin films is identified in real‐time, during the progress of reversible topotactic phase transformation. Using real‐time optical spectroscopy, the phase transition between the two structurally distinct phases (i.e., brownmillerite and perovskite) is quantitatively monitored, and a pressure–temperature phase diagram of the topotactic transformation is constructed for the first time. The transformation at relatively low temperatures is attributed to a markedly small difference in Gibbs free energy compared to the known similar class of materials to date. This study highlights the phase stability and reversibility of SrFeOx thin films, which is highly relevant for energy and environmental applications exploiting the redox reactions. 相似文献
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Thin Films: Topotactic Metal–Insulator Transition in Epitaxial SrFeOx Thin Films (Adv. Mater. 37/2017) 下载免费PDF全文
Amit Khare Dongwon Shin Tae Sup Yoo Minu Kim Tae Dong Kang Jaekwang Lee Seulki Roh In‐Ho Jung Jungseek Hwang Sung Wng Kim Tae Won Noh Hiromichi Ohta Woo Seok Choi 《Advanced materials (Deerfield Beach, Fla.)》2017,29(37)
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Jiaqi Ran Linchuan Wang Mingsu Si Xiaolei Liang Daqiang Gao 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(10):2206367
Promoting the initially deficient but economical catalysts to high-performing competitors is important for developing superior catalysts. Unlike traditional nano-morphology construction methods, this work focuses on intrinsic catalytic activity enhancement via heteroatom doping strategies to induce lattice distortion and optimize spin-dependent orbital interaction to alter charge transfer between catalysts and reactants. Experimentally, a series of different concentrations of fluorine-doped lanthanum cobaltate (Fx-LaCoO3) exhibiting excellent electrocatalytic activity is synthesized, including a low overpotential of 390 mV at j = 10 mA cm−2 for OER and a large half-wave potential of 0.68 V for ORR. Meanwhile, the assembled rechargeable Zn–air batteries deliver an excellent performance with a large specific capacity of 811 mAh/gZn under 10 mA cm−2 and stability of charge/recharge (120 h). Theoretically, taking advantage of density functional theory calculations, it is found that the prominent OER/ORR performance arises from the spin state transition of Co3+ (Low spin state (LS, t2g6eg0) → Intermediate spin state (IS, t2g5eg1) and the mediated d-band center upshift by F atom incorporation. This work establishes a novel avenue for designing superior electrocatalysts in perovskite-based oxides by regulating spin states. 相似文献
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Ji-Soo Jang Jun Kyu Kim Kyeounghak Kim Wan-Gil Jung Chaesung Lim Sangwoo Kim Dong-Ha Kim Bong-Joong Kim Jeong Woo Han WooChul Jung Il-Doo Kim 《Advanced materials (Deerfield Beach, Fla.)》2020,32(46):2003983
The ex-solution phenomenon, a central platform for growing metal nanoparticles on the surface of host oxides in real time with high durability and a fine distribution, has recently been applied to various scientific and industrial fields, such as catalysis, sensing, and renewable energy. However, the high-temperature processing required for ex-solutions (>700 °C) limits the applicable material compositions and has hindered advances in this technique. Here, an unprecedented approach is reported for low-temperature particle ex-solution on important nanoscale binary oxides. WO3 with a nanosheet structure is selected as the parent oxide, and Ir serves as the active metal species that produces the ex-solved metallic particles. Importantly, Ir doping facilitates a phase transition in the WO3 bulk lattice, which further promotes Ir ex-solution at the oxide surface and eventually enables the formation of Ir particles (<3 nm) at temperatures as low as 300 °C. Low-temperature ex-solution effectively inhibits the agglomeration of WO3 sheets while maintaining well-dispersed ex-solved particles. Furthermore, the Ir-decorated WO3 sheets show excellent durability and H2S selectivity when used as sensing materials, suggesting that this is a generalizable synthetic strategy for preparing highly robust heterogeneous catalysts for a variety of applications. 相似文献
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Xinsheng Wang Zhigang Song Wen Wen Haining Liu Juanxia Wu Chunhe Dang Mongur Hossain Muhammad Ahsan Iqbal Liming Xie 《Advanced materials (Deerfield Beach, Fla.)》2019,31(45)
Layered materials with phase transitions, such as charge density wave (CDW) and magnetic and dipole ordering, have potential to be exfoliated into monolayers and few‐layers and then become a large and important subfamily of two‐dimensional (2D) materials. Benefitting from enriched physical properties from the collective interactions, long‐range ordering, and related phase transitions, as well as the atomic thickness yet having nondangling bonds on the surface, 2D phase‐transition materials have vast potential for use in new‐concept and functional devices. Here, potential 2D phase‐transition materials with CDWs and magnetic and dipole ordering, including transition metal dichalcogenides, transition metal halides, metal thio/selenophosphates, chromium silicon/germanium tellurides, and more, are introduced. The structures and experimental phase‐transition properties are summarized for the bulk materials and some of the obtained monolayers. In addition, recent experimental progress on the synthesis and measurement of monolayers, such as 1T‐TaS2, CrI3, and Cr2Ge2Te6, is reviewed. 相似文献
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Systematics in the electrical and magnetic properties of transition metal perovskites LnBO3 (Ln=rare-earth ion, B=3d transition metal) with the variation of Ln and B ions are reviewed. The electrical resistivity and activation energy of LnBO3 compounds increase with the decreasing size of the Ln3+ ion for a given B ion. The low-spin to high-spin transition temperature of Co3+ ion in LnCoO3 similarly increases with the decrease in size of Ln3+ while the magnetic ordering temperatures in LnVO3, LnFeO3, LnCrO3 and LnSrCo2O6 decreases with decreasing size of the rare-earth ion. These results may be understood in terms of the increasing acidity
of the rare earth ion with decreasing size and the competition between the Ln3+ and the B3+ ions for covalency with the oxygen ions. The effect of this competition on the metal oxygen covalency and crystal field parameter
is discussed in relation to the results obtained and Goodenough’s phase diagram. The possibility ofd-f exchange interaction in La1−xLnx NiO3 is also discussed in the light of ESR results.
Communication No. 66 from the Solid State and Structural Chemistry Unit. 相似文献
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One‐Step Solution Phase Growth of Transition Metal Dichalcogenide Thin Films Directly on Solid Substrates 下载免费PDF全文
Anupam Giri Heeseung Yang Kalianan Thiyagarajan Woosun Jang Jae Min Myoung Ranbir Singh Aloysius Soon Kilwon Cho Unyong Jeong 《Advanced materials (Deerfield Beach, Fla.)》2017,29(26)
Ultrathin transition metal dichalcogenides (TMDs) have exotic electronic properties. With success in easy synthesis of high quality TMD thin films, the potential applications will become more viable in electronics, optics, energy storage, and catalysis. Synthesis of TMD thin films has been mostly performed in vacuum or by thermolysis. So far, there is no solution phase synthesis to produce large‐area thin films directly on target substrates. Here, this paper reports a one‐step quick synthesis (within 45–90 s) of TMD thin films (MoS2, WS2, MoSe2, WSe2, etc.) on solid substrates by using microwave irradiation on a precursor‐containing electrolyte solution. The numbers of the quintuple layers of the TMD thin films are precisely controllable by varying the precursor's concentration in the electrolyte solution. A photodetector made of MoS2 thin film comprising of small size grains shows near‐IR absorption, supported by the first principle calculation, exhibits a high photoresponsivity (>300 mA W?1) and a fast response (124 µs). This study paves a robust way for the synthesis of various TMD thin films in solution phases. 相似文献
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Jens Meyer Sami Hamwi Michael Kröger Wolfgang Kowalsky Thomas Riedl Antoine Kahn 《Advanced materials (Deerfield Beach, Fla.)》2012,24(40):5408-5427
During the last few years, transition metal oxides (TMO) such as molybdenum tri‐oxide (MoO3), vanadium pent‐oxide (V2O5) or tungsten tri‐oxide (WO3) have been extensively studied because of their exceptional electronic properties for charge injection and extraction in organic electronic devices. These unique properties have led to the performance enhancement of several types of devices and to a variety of novel applications. TMOs have been used to realize efficient and long‐term stable p‐type doping of wide band gap organic materials, charge‐generation junctions for stacked organic light emitting diodes (OLED), sputtering buffer layers for semi‐transparent devices, and organic photovoltaic (OPV) cells with improved charge extraction, enhanced power conversion efficiency and substantially improved long term stability. Energetics in general play a key role in advancing device structure and performance in organic electronics; however, the literature provides a very inconsistent picture of the electronic structure of TMOs and the resulting interpretation of their role as functional constituents in organic electronics. With this review we intend to clarify some of the existing misconceptions. An overview of TMO‐based device architectures ranging from transparent OLEDs to tandem OPV cells is also given. Various TMO film deposition methods are reviewed, addressing vacuum evaporation and recent approaches for solution‐based processing. The specific properties of the resulting materials and their role as functional layers in organic devices are discussed. 相似文献
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Young‐su Yoon Song‐Ho Byeon In Su Lee 《Advanced materials (Deerfield Beach, Fla.)》2010,22(30):3272-3276
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C.S. Nimisha K. Yellareswar RaoG. Venkatesh G. Mohan RaoN. Munichandraiah 《Thin solid films》2011,519(10):3401-3406
Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by reactive radio frequency (rf) magnetron sputtering from Li3PO4 powder compact target. High deposition rates and ease of manufacturing powder target compared with conventional ceramic Li3PO4 targets offer flexibility in handling and reduce the cost associated. Rf power density varied from 1.7 Wcm− 2 to 3 Wcm− 2 and N2 flow from 10 to 30 sccm for a fixed substrate to target distance of 4 cm for best ionic conductivity. The surface chemical analysis done by X-ray photoelectron spectroscopy showed incorporation of nitrogen into the film as both triply, Nt and doubly, Nd coordinated form. With increased presence of Nt, ionic conductivity of LiPON was found to be increasing. The electrochemical impedance spectroscopy of LiPON films confirmed an ionic conductivity of 1.1 × 10− 6 Scm− 1 for optimum rf power and N2 flow conditions. 相似文献
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Tao Ling Tong Zhang Binghui Ge Lili Han Lirong Zheng Feng Lin Zhengrui Xu Wen‐Bin Hu Xi‐Wen Du Kenneth Davey Shi‐Zhang Qiao 《Advanced materials (Deerfield Beach, Fla.)》2019,31(16)
The practical scale‐up of renewable energy technologies will require catalysts that are more efficient and durable than present ones. This is, however, a formidable challenge that will demand a new capability to tailor the electronic structure. Here, an original electronic structure tailoring of CoO by Ni and Zn dual doping is reported. This changes it from an inert material into one that is highly active for the hydrogen evolution reaction (HER). Based on combined density functional theory calculations and cutting‐edge characterizations, it is shown that dual Ni and Zn doping is responsible for a highly significant increase in HER activity of the host oxide. That is, the Ni dopants cluster around surface oxygen vacancy of the host oxide and provide an ideal electronic surface structure for hydrogen intermediate binding, while the Zn dopants distribute inside the host oxide and modulate the bulk electronic structure to boost electrical conduction. As a result, the dual‐doped Ni, Zn CoO nanorods achieve current densities of 10 and 20 mA cm?2 at overpotentials of, respectively, 53 and 79 mV. This outperforms reported state‐of‐the‐art metal oxide, metal oxide/metal, metal sulfide, and metal phosphide catalysts. 相似文献