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X. Wang

Bio: X. Wang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Hydrogenase mimic & Chemical vapor deposition. The author has an hindex of 17, co-authored 36 publications receiving 1347 citations.

Papers
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Journal ArticleDOI
TL;DR: The isothermal oxidation behavior of bulk Ti3AlC2 has been investigated at 1000-1400 °C in air for exposure times up to 20 h by means of TGA, XRD, SEM and EDS as discussed by the authors.

304 citations

Journal ArticleDOI
TL;DR: In this paper, the electronic and structural properties of the layered ternary compound Ti3AlC2 have been determined using the ab initio pseudopotential method based on density functional theory.
Abstract: The electronic and structural properties of the layered ternary compound Ti3AlC2 have been determined using the ab initio pseudopotential method based on density functional theory. We have obtained the equilibrium lattice parameters, the equilibrium atomic positions in the unit cell, and interatomic distances. The calculated bulk modulus is 190 GPa and is comparable to that of TiC. The band structure, density of states (DOS) and effective charges are presented and compared with those of TiC. The band structure indicates that Ti3AlC2 is an electronic conductor. The electronic structure discloses that the bonding in Ti3AlC2 is anisotropic and metallic–covalent–ionic in nature. Compare to the structure of TiC, the presence of Al changes the Ti–C–Ti–C covalent bond chain into a Ti–C–Ti–C–Ti–Al bond chain through its reaction with Ti, forming the layered structure. Effective charge calculations suggest the ionic formula of Ti3AlC2 to be (Ti1.18+)(Ti0.59+)2(Al0.52−)(C0.92−)2.

163 citations

Journal ArticleDOI
Y. Chen1, X. Wang1, J. Q. Li1, Jiqun Lu1, F. Wang1 
TL;DR: In this article, the performance of polyaniline emeraldine base/epoxy resin (EB/ER) coating on mild steel in 3.5% NaCl solutions of various pH values was investigated by electrochemical impedance spectroscopy (EIS) for 150 days.

161 citations

Journal ArticleDOI
TL;DR: It is disclosed for the first time that the singlet excited state of BODIPY rather than the triplet excited state can drive C-H bond activation to form C-C and C-P bonds smoothly, which offers new methods to promote organic transformation under visible light irradiation.

82 citations

Journal ArticleDOI
TL;DR: In this paper, a facile aqueous approach to synthesize heterostructured CdSe/CdS QDs with all-inorganic chalcogenide S2− ligands under mild conditions is presented.
Abstract: Here we present a facile aqueous approach to synthesize heterostructured CdSe/CdS QDs with all-inorganic chalcogenide S2− ligands under mild conditions. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and steady-state emission spectroscopy demonstrate that the heterostructured CdSe/CdS QDs with sulfur-rich surface composition are formed by heterogeneous nucleation of Cd2+ and S2− precursors on the CdSe QDs. After adsorption of small Ni(OH)2 clusters over the surface in situ, the CdSe/CdS–Ni(OH)2 photocatalyst enables H2 production efficiently with an internal quantum yield of 52% under visible light irradiation at 455 nm, up to an 8-fold increase of activity to that of spherical CdSe QDs–Ni(OH)2 under the same conditions. Femtosecond transient absorption spectroscopy, X-ray transient absorption (XTA) spectroscopy, steady-state and time-resolved emission spectroscopy show that the quasi-type-II band alignment in the CdSe/CdS heterostructure is responsible for the efficiency enhancement of light harvesting and surface/interfacial charge separation in solar energy conversion. The unprecedented results exemplify an easily accessible pattern of aqueous synthesis of all-inorganic heterostructured QDs for advanced photosynthetic H2 evolution.

81 citations


Cited by
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Journal ArticleDOI
13 Feb 2012-ACS Nano
TL;DR: Evidence is presented for the exfoliation of the following MAX phases by the simple immersion of their powders, at room temperature, in HF of varying concentrations for times varying between 10 and 72 h followed by sonication.
Abstract: Herein we report on the synthesis of two-dimensional transition metal carbides and carbonitrides by immersing select MAX phase powders in hydrofluoric acid, HF. The MAX phases represent a large (>60 members) family of ternary, layered, machinable transition metal carbides, nitrides, and carbonitrides. Herein we present evidence for the exfoliation of the following MAX phases: Ti2AlC, Ta4AlC3, (Ti0.5,Nb0.5)2AlC, (V0.5,Cr0.5)3AlC2, and Ti3AlCN by the simple immersion of their powders, at room temperature, in HF of varying concentrations for times varying between 10 and 72 h followed by sonication. The removal of the “A” group layer from the MAX phases results in 2-D layers that we are labeling MXenes to denote the loss of the A element and emphasize their structural similarities with graphene. The sheet resistances of the MXenes were found to be comparable to multilayer graphene. Contact angle measurements with water on pressed MXene surfaces showed hydrophilic behavior.

3,080 citations

Journal ArticleDOI
TL;DR: In this article, a review concisely compiles the recent progress in the fabrication, modification, and major applications of the direct Z-scheme photocatalysts; the latter include water splitting, carbon dioxide reduction, degradation of pollutants, and biohazard disinfection.

1,013 citations

Journal ArticleDOI
TL;DR: A critical review of the M(n + 1)AX(n) phases from a materials science perspective is given in this article, where the authors discuss the potential for low-temperature synthesis, which is essential for deposition of MAX phases onto technologically important substrates.

905 citations

Journal ArticleDOI
TL;DR: The MAX phases are a group of layered ternary compounds with the general formula Mn+1AXn (M: early transition metal; A: group A element; X: C and/or N; n = 1-3), which combine some properties of metals such as good electrical and thermal conductivity, machinability, low hardness, thermal shock resistance and damage tolerance, with those of ceramics, such as high elastic moduli, high temperature strength, and oxidation and corrosion resistance as mentioned in this paper.
Abstract: The MAX phases are a group of layered ternary compounds with the general formula Mn+1AXn (M: early transition metal; A: group A element; X: C and/or N; n = 1–3), which combine some properties of metals, such as good electrical and thermal conductivity, machinability, low hardness, thermal shock resistance and damage tolerance, with those of ceramics, such as high elastic moduli, high temperature strength, and oxidation and corrosion resistance. The publication of papers on the MAX phases has shown an almost exponential increase in the past decade. The existence of further MAX phases has been reported or proposed. In addition to surveying this activity, the synthesis of MAX phases in the forms of bulk, films and powders is reviewed, together with their physical, mechanical and corrosion/oxidation properties. Recent research and development has revealed potential for the practical application of the MAX phases (particularly using the pressureless sintering and physical vapour deposition coating rout...

851 citations

Journal ArticleDOI
TL;DR: In this paper, the authors review the current understanding of the elastic and mechanical properties of bulk MAX phases where they differ significantly from their corresponding MX counterparts, and show that the MAX phases are relatively soft (2.8 GPa), are most readily machinable, and are damage tolerant.
Abstract: The more than 60 ternary carbides and nitrides, with the general formula Mn+1AXn—where n = 1, 2, or 3; M is an early transition metal; A is an A-group element (a subset of groups 13–16); and X is C and/or N—represent a new class of layered solids, where Mn+1Xn layers are interleaved with pure A-group element layers. The growing interest in the Mn+1AXn phases lies in their unusual, and sometimes unique, set of properties that can be traced back to their layered nature and the fact that basal dislocations multiply and are mobile at room temperature. Because of their chemical and structural similarities, the MAX phases and their corresponding MX phases share many physical and chemical properties. In this paper we review our current understanding of the elastic and mechanical properties of bulk MAX phases where they differ significantly from their MX counterparts. Elastically the MAX phases are in general quite stiff and elastically isotropic. The MAX phases are relatively soft (2–8 GPa), are most readily machinable, and are damage tolerant. Some of them are also lightweight and resistant to thermal shock, oxidation, fatigue, and creep. In addition, they behave as nonlinear elastic solids, dissipating 25% of the mechanical energy during compressive cycling loading of up to 1 GPa at room temperature. At higher temperatures, they undergo a brittle-to-plastic transition, and their mechanical behavior is a strong function of deformation rate.

832 citations