Perovskite Oxides: Preparation, Characterizations, and Applications in Heterogeneous Catalysis

Abstract

Perovskite oxides with formula ABO3 or A2BO4 are a very important class of functional materials that exhibit a range of stoichiometries and crystal structures. Because of the structural features, they could accommodate around 90% of the metallic natural elements of the Periodic Table that stand solely or partially at the A and/or B positions without destroying the matrix structure, offering a way of correlating solid state chemistry to catalytic properties. Moreover, their high thermal and hydrothermal stability enable them suitable catalytic materials either for gas or solid reactions carried out at high temperatures, or liquid reactions carried out at low temperatures. In this review, we addressed the preparation, characterization, and application of perovskite oxides in heterogeneous catalysis. Preparation is an important issue in catalysis by which materials with desired textural structure and physicochemical property could be achieved; characterization is the way to explore and understand the textural structures and physicochemical properties of the material; however, application reflects how and where the material could be used and what it can solve in practice, which is the ultimate goal of catalysis. This review is organized in five sections: (1) a brief introduction to perovskite oxides, (2) preparation of perovskite oxides with different textural structures and surface morphologies, (3) general characterizations applied to perovskite oxides, (4) application of perovskite oxides in heterogeneous catalysis, and (5) conclusions and perspectives. We expected that the overview on these achievements could lead to research on the nature of catalytic performances of perovskite oxides and finally commercialization of them for industrial use.

Polymorphism and Structural Distortions of Mixed-Metal Oxide Photocatalysts Constructed with α-U3O8 Types of Layers

“…However, Na2Nb4O11 and Ag2Nb4O11 are not polar at room temperature, and are classified in a rhomobohedral R3c and monoclinic C2/c space groups, respectively [42,43]. Table S2 in the Supporting Information indicates three general trends for extended structures with the composition A m+ (2/m)B4O11: (1) an increase in the "A" site coordination are not polar at room temperature, and are classified in a rhomobohedral R3c and monoclinic C2/c space groups, respectively [42,43]. [44][45][46] shown in Figure 2b.…”

“…Structural families of metal-oxides that have been commonly explored in the literature are ABO 3 pervoskites [1][2][3][4][5], layered Ruddelsden-Popper pervoskites [6][7][8], and spinel structures [9][10][11]. Metal-oxide materials can also be classified by their properties that can include superconductors [12][13][14][15], transparent conducting oxides [16][17][18][19][20], and photocatalysts [21][22][23][24][25][26].…”

“…The photoelectrochemical properties of polycrystalline films of the Cu(I) tantalates of this structural family (e.g., Cu5Ta11O30) have been recently reviewed [85], and this current review will focus on their photocatalytic activity as suspended powders Evaluation of photocatalysts under experimental conditions suitable for water splitting is dependent upon the following: the evolution of O 2 and H 2 gases, stability over time, as a function of wavelength (i.e., ultraviolet or visible light), and overall efficiency of the system [101][102][103][104][105]. Depending upon the overall configuration of the photocatalytic measurements, (i.e., whether in the form of suspended particles or as a polycrystalline film) various parameters are important to assess solar-to-fuel energy conversion, including the photocurrent density, turnover frequency, overall quantum yield, Overall Quantum Yield = rate o f reaction rate o f absorption o f radiation = N mol N ph (1) and the incident photon-to-current-efficiency (IPCE). The photoelectrochemical properties of polycrystalline films of the Cu(I) tantalates of this structural family (e.g., Cu 5 Ta 11 O 30 ) have been recently reviewed [85], and this current review will focus on their photocatalytic activity as suspended powders in aqueous solutions.…”

CO and H2 oxidation over Pt/BaSnO3 catalysts

“…Perovskite type oxides with a general formula ABO 3 or A 2 BO 4 [1] show interesting catalytic properties. They attract great attention as catalysts for many oxidation processes, for example, total oxidation of hydrocarbons (methane, propane) [2,3], chlorinated hydrocarbons [4,5] and ammonia [6], being therefore proposed as an economical substitute for noble metal-based catalysts.…”

Surface-hydrogen-induced metallization and rumpling in thin BaTiO3 films

“…24 OH groups caused by H absorption has also been suggested as a source of resistivity degradation in bulk BTO. 19 The adsorption of atoms and molecules on BTO surfaces is an important topic; perovskites have been shown to be effective catalysts for removing CO and CH 4 , 25 and BTO is a particularly effective catalyst for the combustion of CH 4 . 26 Prior research shows that the adsorption of H 2 O on the TiO 2 -terminated (001)BTO surface leads to disassociation into H + and OH -groups, 27,28 and ~20% of Ti surface atoms have these OH -groups; the OH -adsorbed on Ti is enough to reverse the polarization of the surface TiO 2 layer.…”