Doped Ceria Catalyst System: Catalyzing Carbon Monoxide Transformation (A-Review)

As ceria chemistry broadens, it is needed to generalize the behavior of ceria surfaces towards molecules for carrying out a reaction. The endowing capacity of mobile oxygen due to rapid redox switching between Ce+4/Ce+3 is a key point for ceria containing surfaces. Herein we have presented a review which is broadly divided into two parts. First part focuses on surface property as how electronic structure, vacancy and surface energy would be modified after interaction of ceria with dopant (noble metal, metal of variable oxidation state, higher valent metal and lower valent metal). The second part focuses on catalysis as how the doped ceria surface influences the carbon monoxide transformations (CO oxidation, CO and H2O reaction, CO and NO reaction, CO and H2 reaction). This through study will be helpful to predict the ceria surface for a designed reaction.

Oxygen Generation Using Catalytic Nano/Micromotors

Gaseous oxygen plays a vital role in driving the metabolism of living organisms and has multiple agricultural, medical, and technological applications. Different methods have been discovered to produce oxygen, including plants, oxygen concentrators and catalytic reactions. However, many such approaches are relatively expensive, involve challenges, complexities in post-production processes or generate undesired reaction products. Catalytic oxygen generation using hydrogen peroxide is one of the simplest and cleanest methods to produce oxygen in the required quantities. Chemically powered micro/nanomotors, capable of self-propulsion in liquid media, offer convenient and economic platforms for on-the-fly generation of gaseous oxygen on demand. Micromotors have opened up opportunities for controlled oxygen generation and transport under complex conditions, critical medical diagnostics and therapy. Mobile oxygen micro-carriers help better understand the energy transduction efficiencies of micro/nanoscopic active matter by careful selection of catalytic materials, fuel compositions and concentrations, catalyst surface curvatures and catalytic particle size, which opens avenues for controllable oxygen release on the level of a single catalytic microreactor. This review discusses various micro/nanomotor systems capable of functioning as mobile oxygen generators while highlighting their features, efficiencies and application potentials in different fields.

Oxygen Vacancies in Perovskite Oxide Piezoelectrics

The excellent electro-mechanical properties of perovskite oxide ferroelectrics make these materials major piezoelectrics. Oxygen vacancies are believed to easily form, migrate, and strongly affect ferroelectric behavior and, consequently, the piezoelectric performance of these materials and devices based thereon. Mobile oxygen vacancies were proposed to explain high-temperature chemical reactions half a century ago. Today the chemistry-enabled concept of mobile oxygen vacancies has been extrapolated to arbitrary physical conditions and numerous effects and is widely accepted. Here, this popular concept is questioned. The concept is shown to conflict with our modern physical understanding of ferroelectrics. Basic electronic processes known from mature semiconductor physics are demonstrated to explain the key observations that are groundlessly ascribed to mobile oxygen vacancies. The concept of mobile oxygen vacancies is concluded to be misleading.

Non-ohmic conduction in sodium bismuth titanate: the influence of oxide-ion conduction

A maximum conductivity enhancement of >2000% is achieved in Na0.5Bi0.51TiO3.015 under a small dc bias, in which the highly mobile oxygen ions and the electrode reactions play a critical role.