Oxide ion conductors based on niobium-doped bismuth vanadate: conductivity and phase transition features

Abstract

Oxide ion conductors are technologically important materials, essential for electrochemical devices such as oxygen separation membranes and solid oxide fuel cells (SOFCs). Bi 4 V 2−x Me x O 11−δ (BiMeVOx) is a well-known family of material with high ionic conductivity at low operating temperatures. However, it is often reported to possess three structurally related phase changes that affect the vacancy order/ disorder over the oxygen atom positions. This might be overcome by a careful chemical design of an oxide ion conductor by introducing the stabilizing dopants. Here, it is found that niobium (Nb) doping on the V site can increase the stability (tetragonal structure) and ionic conductivity at a temperature range of 200-600°C. This study demonstrates the effect of the doping amount on the ionic conductivity and characterizes the obtained materials by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analyses. The oxidation state of vanadium that related to the electronic structure of BiMeVOx is investigated by X-ray photoelectron spectroscopy (XPS) analysis. It is expected to understand the conductivity and phase transition features of this kind of oxide ion conductor.

Role of Al and Ti doping in modulating electrical properties of BIVOX system

“…Particularly for the compositions, with the tragonal phase at room temperature, a steady shift towards lower 2θ, has been observed. This shifting of peak position indicates the lattice expansion due to the substitution of V by Al and Ti in the initial structure of the parent compound [28].…”

Niobium Doping in BiVO4: Interplay Between Effective Mass, Stability, and Pressure

“…In fact, doping with appropriate ions and synthesizing it in a corresponding tuned chemical environment is one of the good strategies to overcome the limitations and hence enhancing the photocatalytic properties of BiVO 4 . There have been both experimental and theoretical works of BiVO 4 in the presence of defects and impurities, to understand such strategies. Theoretical predictions of such strategies and growth environment for the desired dopant in BiVO 4 can be an important tool to expedite the search process.…”

Multifunctionality of Partially Reduced Graphene Oxide–CrVO4Nanocomposite: Electrochemical and Photocatalytic Studies with Theoretical Insight from Density Functional Theory

“…The electronic band gap of the compounds is evaluated with the help of diffuse reflectance UV visible spectra, where the band gap of CrVO 4 and rGO−CrVO 4 were found to be 2. 44…”

“…It is very clear from Figure that the quantum capacitance is higher for GO-supported CrVO 4 compared to pure CrVO 4 which supports our experimental data. Here, we point out that in experiment, we measure total capacitance, and for low-dimensional electrode, it is expressed as where C EDL is the EDLC which depends on electrode–electrolyte interfacial interaction. In Figure , we plot the partial density for Cr d orbital (lower panel), V d orbital, O p orbital, and C p orbital (upper panel) for (100) surface of CrVO 4 and GO + (100) surface of CrVO 4 .…”

“…Hence, vanadium-based oxides possess disparate structure combined with variations in physical and chemical properties. , Transition metal vanadates are widely studied for electrochemical, catalysis, gas sensing, and photoluminescence applications. Orthovanadates such as zinc vanadate, sodium vanadate, silver vanadate, niobium-doped bismuth vanadate, manganese vanadate, lithium vanadate, copper vanadate, bismuth vanadate, RVO 4 where (R = La, Ca, Nd, Sm, Eu, and Gd), lanthanum vanadate, and BiVO 4 /FeVO 4 heterojunction have shown great electrochemical properties. These wide range of compounds are scarcely studied as composites with carbonaceous materials, and this leaves huge potential to develop new multifunctional materials for future applications.…”