20 research outputs found
The efficient faradaic Li <inf>4</inf> Ti <inf>5</inf> O <inf>12</inf> @C electrode exceeds the membrane capacitive desalination performance
No full text10.1039/c9ta00700hJournal of Materials Chemistry A7158912-892
ATOMIC SCALE INVESTIGATIONS OF SURFACE REACTION MECHANISM BETWEEN TRANSITION METAL PHTHALOCYANINE WITH SMALL GAS MOLECULES
No full textPh.DDOCTOR OF PHILOSOPH
High quality CuInP2S6 single crystal for intrinsic electric property
No full textWhat is the nature of the electric (dielectric/ferroelectric) properties of CuInP2S6 (CIPS)? CIPS, considered an emerging two-dimensional (2D) ferroelectric, has been well explored in various properties and applications. However, the most important and fundamental nature, i.e. dielectric/ferroelectric property, has been controversial, because high-quality CIPS samples are grossly deficient. In this work, single crystal CIPS is successfully synthesized by the chemical vapour transport method, which presents “high quality” in terms of high purity, excellent crystallinity, uniform composition, and defect-free structure etc. that are confirmed through comprehensive characterization techniques. With performing high-quality single crystal, we fully uncover the intrinsic electric properties of CIPS through accurately identifying the atomic arrangement, electron configuration, magnetic, dielectric, and ferroelectric properties that should reach a consensus on such a disputed CIPS material. These findings serve as a pivotal benchmark for a comprehensive understanding of the inherent electric characteristics of CIPS, offering valuable insights for its future modifications and applications in various applications
Atomic-level direct imaging for Cu(I) multiple occupations and migration in 2D ferroelectric CuInP2S6
No full textAbstract CuInP2S6 (CIPS) is an emerging 2D ferroelectric material known for disrupting spatial inversion symmetry due to Cu(I) position switching. Its ferroelectricity strongly relies on the Cu(I) atom/ion occupation ordering and dynamics. Nevertheless, the accurate Cu(I) occupations and correlated migration dynamics under the externally applied energy, which are key to unlocking ferroelectric properties, remain controversial and unresolved. Herein, an atomic-level direct imaging through aberration-corrected scanning transmission electron microscopy is performed to precisely trace the Cu(I) dynamic behaviours under electron-beam irradiation along (100)-CIPS. It clearly demonstrates that Cu(I) possesses multiple occupations, and Cu(I) could migrate to the lattice, vacancy, interstitial and interlayer sites between the InS6 octahedral skeletons of CIPS to form local Cu x InP2S6 (x = 2-4) structure. Cu(I) multi-occupations induced lattice stress results in a layer sliding along the b-axis direction generating a sliding size of 1/6 b lattice constant. The Cu x InP2S6 (x = 2-4) exists in a type of dynamic structure, only metastable with electron dose over 50 e− Å−2, thus generating a dynamic process of {\mbox{C}}{{\mbox{u}}}_{x}{\mbox{In}}{{\mbox{P}}}_{2}{{\mbox{S}}}_{6}(x=2-4)\rightleftharpoons {\mbox{CuIn}}{{\mbox{P}}}_{2}{{\mbox{S}}}_{6} C u x In P 2 S 6 ( x = 2 − 4 ) ⇌ CuIn P 2 S 6 , a completely unreported phenomenon. These findings shed light on the unveiled mechanism underlying Cu(I) migration in CIPS, providing crucial insights into the fundamental processes that govern its ferroelectric properties
Enhanced Energy Storage Performance in Paraelectric–Ferroelectric Bipolymer-Based PMMA-P(VDF-HFP) Composite Films via Polydopamine-Coated KNb<sub>3</sub>O<sub>8</sub> Fillers
No full textEnhancing
the breakdown strength (Eb) and polarization
of the polymer-based composites through improving
the effective interface bonding between the inorganic fillers and
polymer matrix is always pursued to achieve high electrostatic energy
storage performances. Along with this, paraelectric–ferroelectric
(P–F) structured bipolymer PMMA-P(VDF-HFP) was copolymerized
and blended to maintain the high Eb but
reduce the residual polarization, and meanwhile, potassium triniobate
(KNb3O8) rods synthesized by a molten salt (KCl
and K2SO4) method were surface-modified using
a polydopamine (PDA) shell to form fillers for the fabrication of
the composite films that were prepared by a solution casting process.
The fabricated PDA@KNb3O8/PMMA-P(VDF-HFP) composite
film by filling only a tiny amount of PDA@KNb3O8 (1.0 wt %) exhibits a much enhanced dielectric constant (ε
∼ 9) and polarization (Pmax ∼
6.9) and large Eb (∼600 MV m–1), therefore giving rise to a high energy density
of 15.30 J cm–3 combined with a discharge energy
efficiency of 65%. The results herein can be comparative and superior
to those of many high-energy storage inorganic–polymer systems
that may render this system much potential for dielectric energy storage
capacitors
Molecular-Scale Investigation of the Thermal and Chemical Stability of Monolayer PTCDA on Cu(111) and Cu(110)
No full textFluorination-guided Li-anchoring behaviors on phthalocyanines
No full textUnderstanding the interactions between metallic lithium (Li) and the anchoring sites/groups is essential for the design of stable host materials and artificial interphases in lithium metal batteries (LMBs). Here, we investigate the interactions of lithium with the polar organic functional groups in copper(II) hexadecafluorophthalocyanine (F16CuPc) and copper(II) phthalocyanine (CuPc) through the combination of in-situ X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), synchrotron-based near-edge X-ray absorption fine structures (NEXAFS), and density functional theory (DFT) calculations. It is revealed that the highly polar C-F bonds can anchor the Li atom via ionic Li-F interaction around the outer aza bridge N atoms in F16CuPc, while Li tends to interact with the inner pyrrolic N atoms around the central Cu in CuPc. The central Cu(II) ions in both molecules are reduced to Cu(I) upon interaction with Li. Electrons are transferred from Li to the lowest unoccupied molecular orbitals (LUMO) of both F16CuPc and CuPc molecules, as revealed by the UPS and NEXAFS measurements. Our systematic study can shed light on the design of anode materials by adding polar functional groups for applications in lithium metal batteries (LMBs).Ministry of Education (MOE)The authors acknowledge the financial support from the Natural Science Foundation of China (U2032147), Singapore MOE Tier II grant R143-000-A29-112, and Academic Research Fund Tie I grant RG104/18
Growth of Quasi-Free-Standing Single-Layer Blue Phosphorus on Tellurium Monolayer Functionalized Au(111)
No full text
