WorldCat Identities

Tao, Quanzheng

Overview
Works: 16 works in 17 publications in 1 language and 17 library holdings
Roles: Author
Publication Timeline
.
Most widely held works by Quanzheng Tao
Synthesis and characterization of two- and three-dimensional nanolaminated carbides by Quanzheng Tao( Book )

2 editions published in 2020 in English and held by 2 WorldCat member libraries worldwide

This thesis is focused towards the synthesis and characterization of novel nanolaminated materials in primarily bulk (powder) form. Of particular interest is magnetic materials, or laminates that can be used as precursor for two-dimensional (2D) materials. 2D materials typically display a large surface-to-volume ratio, and as such they are very promising for applications within energy storage and catalysis. A more recently discovered family of 2D transition metal carbides/nitrides, called MXenes, are currently attracting a lot of attention. MXenes are produced by selective etching of parent 3D nanolaminates, so called MAX phases, facilitating removal of selected atomic layers, and formation of 2D sheets. In my work on new nanolaminates as precursors for 2D materials, I have synthesized (Mo 2/3 Sc 1/3) 2 AlC and have studied its crystal structure. It was found that Mo and Sc are chemically ordered in the metal layers, with the in-plane ordering motivating the notation i -MAX for this new type of MAX phase alloy. By selective etching of Sc and Al, we thereafter produced a 2D materials with ordered vacancies, Mo 1.33 C, and studied the electrochemical properties. It was found that the material displayed a high capacitance, ~1200 F cm -3, which is 65% higher that the counterpart without vacancies, Mo 2 C.I also synthesized a previously not known out-of-plane ordered Mo 2 ScAlC 2 MAX phase. By selective etching of Al, we produced a 2D material, Mo 2 ScC 2, which is correspondingly ordered in the out-of-plane direction. Another related laminated material was also discovered and synthesized, Sc 2 Al 2 C 3, and its crystal structure was determined. The material is potentially useful for conversion into a 2D material. I have also shown that Sc 2 Al 2 C 3 is an example of a series of materials with the same crystal structure, with Sc replaced by other metals. Magnetic materials are used in many applications, such as for data storage devices. In particular, layered magnetic materials are of interest due to their anisotropic structure and potential formation of interesting magnetic characteristics. I have been synthesizing and characterizing magnetic nanolaminates, starting with the (V, Mn) 3 GaC 2 MAX phase in the form of an epitaxial thin film. Analysis of the magnetic behavior showed a ferromagnetic response above room temperature I thereafter showed that our previously discovered family of i -MAX phases could be expanded with a subclass of ordered nanolaminates based on rare earth (RE) elements, of the general formula (Mo 2/3 RE 1/3) 2 AlC, where RE=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. I studied their crystal structure by scanning transmission microscopy (STEM), X-ray diffraction (XRD), and neutron diffraction. We found that these phases can crystalize in three different structures, of space group C 2/ m, C 2/ c, and Cmcm, respectively. The magnetic behavior was studied and the magnetic structure of two materials could be determined. We suggest that the complex behavior identified is due to competing magnetic interaction and frustration. I also synthesized another rare earth-based nanolaminate, Mo 4 Ce 4 Al 7 C 3 . The crystal structure was investigated by single crystal X-ray diffraction and STEM. Magnetization analysis reveal a ferromagnetic ground state below 10.5 K. X-ray absorption near-edge structure provide evidence that Ce is in a mixed-valence state. X-ray magnetic circular dichroism shows that only one of the two Ce sites are magnetic
A flexible semitransparent photovoltaic supercapacitor based on water-processed MXene electrodes by Qin Leiqiang( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Solar energy, although it has the highest power density available in terms of renewable energy, has the drawback of being erratic. Integrating an energy harvesting and storage device into photovoltaic energy storage modules is a viable route for obtaining self-powered energy systems. Herein, an MXene-based all-solution processed semitransparent flexible photovoltaic supercapacitor (PSC) was fabricated by integrating a flexible organic photovoltaic (OPV) with Ti3C2Tx MXene as the electrode and transparent MXene supercapacitors with an organic ionogel as the electrolyte in the vertical direction, using Ti3C2Tx thin film as a common electrode. In the quest for a semitransparent flexible PSC, Ti3C2Tx MXene was first used as a transparent electrode for OPV with a high power conversion efficiency of 13.6%. The ionogel electrolyte-based transparent MXene supercapacitor shows a high volumetric capacitance of 502 F cm( -3) and excellent stability. Finally, a flexible PSC with a high average transmittance of over 33.5% was successfully constructed by all-solution processing and a remarkable storage efficiency of 88% was achieved. This strategy enables a simple route for fabricating MXene based high-performance all-solution-processed flexible PSCs, which is important for realizing flexible and printable electronics for future technologies
Polymer-MXene composite films formed by MXene-facilitated electrochemical polymerization for flexible solid-state microsupercapacitors by Leiqiang Qin( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

Materials with tailored properties are crucial for high performance electronics applications. Hybrid materials composed of inorganic and organic components can possess unique merits for broad application by synergy between the advantages the respective material type offers. Here we demonstrate a novel electrochemical polymerization (EP) enabled by a 2D transition metal carbide MXene for obtaining conjugated polymer-MXene composite films deposited on conducting substrates without using traditional electrolytes, indispensable compounds for commonly electrochemical polymerization. The universality of the process provides a novel approach for EP allowing fast facile process for obtaining different new polymer/MXene composites with controlled thickness and micro-pattern. Furthermore, high performance microsupercapacitors and asymmetric microsupercapacitors are realized based on the excellent composites benefiting from higher areal capacitance, better rate capabilities and lower contact resistance than conventional electropolymerized polymers. The AMSCs exhibit a maximum areal capacitance of 69.5 mF cm(-2), an ultrahigh volumetric energy density (250.1 mWh cm(-3)) at 1.6 V, and excellent cycling stability up to 10000 cycles. The excellent electrochemical properties of the composite polymerized with MXene suggest a great potential of the method for various energy storage applications
Theoretical stability and materials synthesis of a chemically ordered MAX phase, Mo2ScAlC2, and its two-dimensional derivate Mo2ScC2 MXene by Rahele Meshkian( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

We present theoretical prediction and experimental evidence of a new MAX phase alloy, Mo2ScAlC2, with out-of-plane chemical order. Evaluation of phase stability was performed by ab initio calculations based on Density Functional Theory, suggesting that chemical order in the alloy promotes a stable phase, with a formation enthalpy of -24 meV/atom, as opposed to the predicted unstable Mo3AlC2 and Sc3AlC2. Bulk synthesis of Mo2ScAlC2 is achieved by mixing elemental powders of Mo, Sc, Al and graphite which are heated to 1700 degrees C. High resolution transmission electron microscopy reveals a chemically ordered structure consistent with theoretical predictions with one Sc layer sandwiched between two Mo-C layers. The two-dimensional derivative, the MXene, is produced by selective etching of the Al-layers in hydrofluoric acid, resulting in the corresponding chemically ordered Mo2ScC2, i.e. the first Sc-containing MXene. The here presented results expands the attainable range of MXene compositions and widens the prospects for property tuning. (C)2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Rare-earth (RE) nanolaminates Mo4RE4Al7C3 featuring ferromagnetism and mixed-valence states by Quanzheng Tao( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Rare-earth-based (RE) nanolaminates have attracted attention recently because of their complicated magnetism and their potential as precursors for strongly correlated two-dimensional materials. In this work, we synthesized a class of nanolaminates with a Mo4RE4Al7C3 chemistry, where RE = Ce or Pr. Powder samples of both phases were characterized with respect to structure and composition. Single crystals of Mo4Ce4Al7C3 were used for magnetization measurements. The crystal structure was investigated by means of x-ray diffraction and scanning transmission electron microscopy. Magnetization analysis reveals a ferromagnetic ground state with a Curie temperature of similar to 10.5 K. X-ray absorption near-edge structure provides experimental evidence that Ce is in a mixed-valence state. X-ray magnetic circular dichroism shows that only the Ce atoms with 4f(1) configuration occupying one of the two possible sites are ferromagnetically coupled, with a saturation moment of similar to 1.2 mu(B) per atom. We thus classify Mo4Ce4Al7C3 as a ferromagnetic, mixed-valence compound
Theoretical Analysis, Synthesis, and Characterization of 2D W1.33C (MXene) with Ordered Vacancies by Rahele Meshkian( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

Synthesis of delaminated 2D W1.33C (MXene) has been performed by selectively etching Al as well as Sc/Y from the recently discovered nanolaminated i-MAX phases (W2/3Sc1/3)(2)AlC and (W2/3Y1/3)(2)AlC. Both quaternary phases produce MXenes with similar flake morphology and with a skeletal structure due to formation of ordered vacancies. The measured O, OH, and F terminations, however, differ in amount as well as in relative ratios, depending on parent material, evident from X-ray photoelectron spectroscopy. These findings are correlated to theoretical simulations based on first-principles, investigating the W1.33C, and the effect of termination configurations on structure, formation energy, stability, and electronic structure. The theoretical results indicate a favored F-rich surface composition, though with a system going from insulating/semiconducting to metallic for different termination configurations, suggesting a high tuning potential of these materials. Additionally, free-standing W1.33C films of 2-4 mu m thickness and with up to 10 wt % polymer (PEDOT:PSS) were tested as electrodes in supercapacitors, showing capacitances up to 600 F cm(-3) in 1 M H2SO4 and high capacitance retention for at least 10000 cycles at 10 A g(-1). This is highly promising results compared to other W-based materials to date
Evidence for ferromagnetic ordering in the MAX phase (Cr0.96Mn0.04)(2)GeC by O Rivin( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

Magnetic ordering in the MAX phase (Cr0.96Mn0.04)(2)GeC is investigated by means of neutron powder diffraction (NPD). Upon cooling, the temperature dependence of the magnetization shows a two-step increase. The NPD refinement reveals that the first step, at 300 K, and the second step, at 38 K, originate from a collinear magnetic structure within the MAX phase and a spinel MnCr2O4 impurity phase, respectively. The former magnetic structure is oriented perpendicular to the c axis, with a net magnetic moment of similar to 0.6(2) mu(B) per Cr/Mn atom at 50 K. This is the first direct evidence for magnetic ordering within a bulk MAX phase. [GRAPHICS] IMPACT STATEMENT Direct neutron diffraction evidence for magnetic ordering in a bulk (Cr0.96Mn0.04)(2)GeC polycrystalline MAX phase sample is presented for the first time
Prediction and synthesis of a family of atomic laminate phases with Kagome-like and in-plane chemical ordering by Martin Dahlqvist( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

The enigma of MAX phases and their hybrids prevails. We probe transition metal (M) alloying in MAX phases for metal size, electronegativity, and electron configuration, and discover ordering in these MAX hybrids, namely, (V2/3Zr1/3)(2)AlC and (Mo2/3Y1/3)(2)AlC. Predictive theory and verifying materials synthesis, including a judicious choice of alloying M from groups III to VI and periods 4 and 5, indicate a potentially large family of thermodynamically stable phases, with Kagome-like and in-plane chemical ordering, and with incorporation of elements previously not known for MAX phases, including the common Y. We propose the structure to be monoclinic C2/c. As an extension of the work, we suggest a matching set of novel MXenes, from selective etching of the A-element. The demonstrated structural design on simultaneous two-dimensional (2D) and 3D atomic levels expands the property tuning potential of functional materials
Atomically Layered and Ordered Rare-Earth i-MAX Phases: A New Class of Magnetic Quaternary Compounds by Quanzheng Tao( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

In 2017, we discovered quaternary i-MAX phases atomically layered solids, where M is an early transition metal, A is an A group element, and X is C-with a ((M2/3M1/32)-M-1)(2)AC chemistry, where the M-1 and M-2 atoms are in-plane ordered. Herein, we report the discovery of a class of magnetic i-MAX phases in which bilayers of a quasi-2D magnetic frustrated triangular lattice overlay a Mo honeycomb arrangement and an Al Kagome lattice. The chemistry of this family is (Mo2/3RE1/3)(2)AlC, and the rare-earth, RE, elements are Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. The magnetic properties were characterized and found to display a plethora of ground states, resulting from an interplay of competing magnetic interactions in the presence of magnetocrystalline anisotropy
Out-Of-Plane Ordered Laminate Borides and Their 2D Ti-Based Derivative from Chemical Exfoliation by Martin Dahlqvist( )

1 edition published in 2021 in English and held by 1 WorldCat member library worldwide

Exploratory theoretical predictions in uncharted structural and compositional space are integral to materials discoveries. Inspired by M5SiB2 (T2) phases, the finding of a family of laminated quaternary metal borides, M M-4 SiB2, with out-of-plane chemical order is reported here. 11 chemically ordered phases as well as 40 solid solutions, introducing four elements previously not observed in these borides are predicted. The predictions are experimentally verified for Ti4MoSiB2, establishing Ti as part of the T2 boride compositional space. Chemical exfoliation of Ti4MoSiB2 and select removal of Si and MoB2 sub-layers is validated by derivation of a 2D material, TiOxCly, of high yield and in the form of delaminated sheets. These sheets have an experimentally determined direct band gap of approximate to 4.1 eV, and display characteristics suitable for supercapacitor applications. The results take the concept of chemical exfoliation beyond currently available 2D materials, and expands the envelope of 3D and 2D candidates, and their applications
Single Crystal Growth and Structural Characterization of Theoretically Predicted Nanolaminates M2Al2C3, Where M = Sc and Er by Quanzheng Tao( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Nanolaminated materials including magnetic ele-ments are of special interest for commonly observed nontrivial magnetic characteristics and as potential precursors for 2D materials. Here, we explore the previously unknown layered phase M2Al2C3, where M = Sc and Er. Sc2Al2C3 was synthesized as single crystals of similar to mm(2) size, and its structure was determined by single crystal X-ray diffraction and scanning transmission electron microscopy. Evaluation of phase stability and possible vacancy formation based on first-principles calculations confirms the attained phase and suggests full occupancy on both the Al and C sites. Potential realization of the hypothetical phase Y2Al2C3 is also proposed. Furthermore, we also demonstrate that Er2Al2C3 can be synthesized in powder form, providing experimental evidence for stoichiometries based on rare earth elements, which, in turn, suggests possible incorporation of other lanthanides
Two-Dimensional Molybdenum Carbide (MXene) with Divacancy Ordering for Brackish and Seawater Desalination via Cation and Anion Intercalation by Pattarachai Srimuk( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Ion intercalation materials are emerging as a highly attractive class of electrodes for efficient energy water desalination. Most materials and concepts so far have focused on the removal of cations (especially sodium). Anion intercalation, however, remains poorly investigated in water desalination. We present a study on the capability of Mo1.33C-MXene for removing cations and anions and demonstrate the desalination performance in brackish water and seawater concentrations. Mo1.33C-MXene was prepared via acid treatment of the transition metal carbide MAX phase (Mo(2/)3Sc(1/3))(2)AlC. Binder-free electrodes were obtained by entangling MXene with carbon nanotubes and tested without the use of any ion exchange membrane at low (5 mM NaCl) and high (600 mM NaCl) salt concentrations. Such electrodes showed a promising desalination performance of 15 mg/g in 600 mM NaCl with high charge efficiency up to 95%. By employing chemical online monitoring of the effluent stream, we separated the cation and anion intercalation capacity of the electrode material
Bioinspired multisensory neural network with crossmodal integration and recognition by Hongwei Tan( )

1 edition published in 2021 in English and held by 1 WorldCat member library worldwide

The integration and interaction of vision, touch, hearing, smell, and taste in the human multisensory neural network facilitate high-level cognitive functionalities, such as crossmodal integration, recognition, and imagination for accurate evaluation and comprehensive understanding of the multimodal world. Here, we report a bioinspired multisensory neural network that integrates artificial optic, afferent, auditory, and simulated olfactory and gustatory sensory nerves. With distributed multiple sensors and biomimetic hierarchical architectures, our system can not only sense, process, and memorize multimodal information, but also fuse multisensory data at hardware and software level. Using crossmodal learning, the system is capable of crossmodally recognizing and imagining multimodal information, such as visualizing alphabet letters upon handwritten input, recognizing multimodal visual/smell/taste information or imagining a never-seen picture when hearing its description. Our multisensory neural network provides a promising approach towards robotic sensing and perception. Human-like robotic sensing aims at extracting and processing complicated environmental information via multisensory integration and interaction. Tan et al. report an artificial spiking multisensory neural network that integrates five primary senses and mimics the crossmodal perception of biological brains
Stoichiometry and surface structure dependence of hydrogen evolution reaction activity and stability of MoxC MXenes by Saad Intikhab( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

The exploration of non-precious catalysts for the hydrogen evolution reaction (HER) remains critical in the commercialization of electrochemical energy storage and conversion technologies. Two-dimensional transitional metal carbides called MXenes have been found to have great potential as electrocatalysts for HER. In this work, we synthesize two molybdenum-based MXenes: Mo1.33CTz and Mo2CTz, and measure their HER activity and operational durability. The ordered divacancies on the basal planes of Mo1.33CTz cause a marked decrease in HER activity compared to Mo2CTz. The stoichiometry and atomic surface structure of MXenes is found to be critically important for catalytic activity while having less of an impact on operational durability. This work provides insight for the development of active 2D materials, in general and MXenes in particular for HER and other technologically relevant electrochemical reactions. (C) 2019 Elsevier Inc. All rights reserved
Theoretical Prediction and Synthesis of a Family of Atomic Laminate Metal Borides with In-Plane Chemical Ordering by Martin Dahlqvist( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

All atomically laminated MAB phases (M = transition metal, A = A-group element, and B = boron) exhibit orthorhombic or tetragonal symmetry, with the only exception being hexagonal Ti2InB2. Inspired by the recent discovery of chemically ordered hexagonal carbides, i-MAX phases, we perform an extensive first-principles study to explore chemical ordering upon metal alloying of M2AlB2 (M from groups 3 to 9) in orthorhombic and hexagonal symmetry. Fifteen stable novel phases with in-plane chemical ordering are identified, coined i-MAB, along with 16 disordered stable alloys. The predictions are verified through the powder synthesis of Mo4/3Y2/3 AlB2 and Mo4/3Sc2/3AlB2 of space group R (3) over barm (no. 166), displaying the characteristic in-plane chemical order of Mo and Y/Sc and Kagome ordering of the Al atoms, as evident from X-ray diffraction and electron microscopy. The discovery of i-MAB phases expands the elemental space of these borides with M = Sc, Y, Zr, Hf, and Nb, realizing an increased property tuning potential of these phases as well as their suggested potential twodimensional derivatives
Magnetic properties and structural characterization of layered (Cr0.5Mn0.5)(2)AuC synthesized by thermally induced substitutional reaction in (Cr0.5Mn0.5)(2)GaC by Chung-Chuan Lai( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

The magnetic properties of the new phase (Cr0.5Mn0.5)(2)AuC are compared to the known MAX-phase (Cr0.5Mn0.5)(2)GaC, where the former was synthesized by thermally induced substitution reaction of Au for Ga in (Cr0.5Mn0.5)(2)GaC. The reaction introduced a lattice expansion of similar to 3% along the c-axis, an enhancement of the coercive field from 30 mT to 140 mT, and a reduction of the Curie temperature and the saturation magnetization. Still, (Cr0.5Mn0.5)(2)AuC displays similar features in the magnetic field-and temperature-dependent magnetization curves as previously reported magnetic MAX phases, e.g., (Cr0.5Mn0.5)(2)GaC and (Mo0.5Mn0.5)(2)GaC. Thework suggests a pathway for tuning the magnetic properties of MAX phases. (c) 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license
 
moreShow More Titles
fewerShow Fewer Titles
Audience Level
0
Audience Level
1
  General Special  
Audience level: 0.95 (from 0.85 for Synthesis ... to 0.96 for Synthesis ...)

Languages
English (17)