Influence of heat treatment on the phase transition of ZrMo2O8 and photocatalytic activity

Fan

et al. 2015

J Sol-Gel Sci Technol

Cubic ZrMo 2-x V x O 8-x/2 (0 B x B 0.5) compounds, with well-defined nanorods morphology, were synthesized by a facile sol-gel process without using any surfactant or template. The resulting products were characterized by the X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal mechanical analyzer and UV-vis diffuse reflectance spectra (UV-vis DRS). The results indicated that V-doping did not influence the crystal structure and negative thermal expansion (NTE) property, but made rods size increase. Narrowed band gap was observed in V-doped ZrMo 2 O 8 . The resultant V-doped ZrMo 2 O 8 samples, as compared with pure ZrMo 2 O 8 , exhibited improved UV-light photocatalytic activity, during the photocatalytic degradation of rhodamine B. The mechanism was supposed that the V-doping gave rise to the formation of oxygen vacancies which could enhance photocatalytic performance by reducing the recombination of electrons and holes. In addition, cubic ZrMo 2-x V x O 8-x/2 also displayed reliable recycling photocatalytic performance and satisfying UVlight catalytic activity for the organic pollutant. Furthermore, all of the resulting cubic ZrMo 2-x V x O 8-x/2 showed excellent NTE property from 25 to 450°C. Graphical Abstract TEM images of (a) pure ZrMo 2 O 8 and (b) ZrMo 1.7 V 0.3 O 7.85 ; (c) RhB degradation under UVlight illumination for 180 min in the presence of cubic ZrMo 2-x V x O 8-x/2 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) photocatalysts.

Section: Introductionmentioning

confidence: 98%

Synthesis, photocatalytic performance and negative thermal expansion property of nanorods ZrMo2−x V x O8−x/2 with cubic structure

Fan

et al. 2015

J Sol-Gel Sci Technol

“…ZrMo 2 O 8 has several crystal phases: monoclinic phase (β), trigonal phase (α), cubic phase (γ), orthorhombic phase (LT) and high-pressure phases (monoclinic (δ) and triclinic (ε)). Their conversion is mainly caused by temperature and pressure [56]. The relatively stable crystal phases, under atmospheric pressure, are the α and β crystal phases [43].…”

Section: Introductionmentioning

confidence: 99%

“…•iPrOH as a precursor to form ZrMo 2 O 8 pristine gels, which were later subjected to heat treatment to obtain α-ZrMo 2 O 8 ; Shivanekar and Chudasama[60] used zirconyl chloride octahydrate and ammonium molybdate as raw materials to synthesize ZrMo 2 O 8 for the catalytic decomposition of hydrogen peroxide; Lind et al[54] obtained γ-ZrMo 2 O 8 by calcinating zirconium molybdate precursors for the synthesis of cubicphase zirconium tungstate in the first preparation and characterization of γ-ZrMo 2 O 8 ; Lind et al[58] found that zirconium perchlorate was the most suitable precursor, followed by zirconium nitrate and zirconium chloride, when forming ZrMo 2 O 8 with a rod-shaped structure; Mancheva et al[56] prepared ZrMo 2 O 8 precursors with ZrOCl 2 •2H 2 O and Na 2 MoO 4 •2H 2 O as raw materials using a co-precipitation method, and systematically investigated the phase transition conditions of ZrMo 2 O 8 . ZrMo 2 O 8 also shows advantages in electrochemical detection.…”

mentioning

confidence: 99%

Zirconium Molybdate Nanocomposites’ Sensing Platform for the Sensitive and Selective Electrochemical Detection of Adefovir

Xiao

Yao

et al. 2022

Molecules

Adefovir (ADV) is an anti-retroviral drug, which can be used to treat acquired immune deficiency syndrome (AIDS) and chronic hepatitis B (CHB), so its quantitative analysis is of great significance. In this work, zirconium molybdate (ZrMo2O8) was synthesized by a wet chemical method, and a composite with multi-walled carbon nanotubes (MWCNTs) was made. ZrMo2O8-MWCNTs composite was dropped onto the surface of a glassy carbon electrode (GCE) to prepare ZrMo2O8-MWCNTs/GCE, and ZrMo2O8-MWCNTs/GCE was used in the electrochemical detection of ADV for the first time. The preparation method is fast and simple. The materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry (CV). It was electrochemically analysed by differential pulse voltammetry (DPV). Compared with single-material modified electrodes, ZrMo2O8-MWCNTs/GCE showed a vastly improved electrochemical response to ADV. Moreover, the sensor complements the study of the electrochemical detection of ADV. Under optimal conditions, the proposed electrochemical method showed a wide linear range (from 1 to 100 μM) and a low detection limit (0.253 μM). It was successfully tested in serum and urine. In addition, the sensor has the advantages of a simple preparation, fast response, good reproducibility and repeatability. It may be helpful in the potential applications of other substances with similar structures.

Giant Volume Change and Topological Gaps in Temperature‐ and Pressure‐Induced Phase Transitions: Experimental and Computational Study of ThMo₂O₈

Xiao

Kegler

Gesing

et al. 2015

Chemistry A European J

By applying high temperature (1270 K) and high pressure (3.5 GPa), significant changes occur in the structural volume and crystal topology of ThMo2 O8 , allowing the formation of an unexpected new ThMo2 O8 polymorph (high-temperature/high-pressure (HT/HP) orthorhombic ThMo2 O8 ). Compared with the other three ThMo2 O8 polymorphs prepared at the ambient pressure (monoclinic, orthorhombic, and hexagonal phases), the molar volume for the quenched HT/HP-orthorhombic ThMo2 O8 is decreased by almost 20 %. As a result of such a dramatic structural transformation, a permanent high-pressure quenchable state is able to be sustained when the pressure is released. The crystal structures of the three ambient ThMo2 O8 phases are based on three-dimensional (3D) frameworks constructed from corner-sharing ThOx (x=6, 8, or 9) polyhedra and MoO4 tetrahedra. The HT/HP-orthorhombic ThMo2 O8 , however, crystallizes in a novel structural topology, exhibiting very dense arrangements of ThO11 and MoO4+1 polyhedra connecting along the crystallographic c axis. The phase transitions among all four of these ThMo2 O8 polymorphs are unveiled and fully characterized with regard to the structural transformation, thermal stability, and vibrational properties. The complementary first principles calculations of Gibbs free energies reveal the underlying energetics of the phase transition, which support the experimental findings.