Role of Pr-Vacancies and O-Interstitials on the Activity and Stability of (Pr1-xLnx)2NiO4 (Ln = La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) towards Oxygen Reduction Reactions: A DFT Study

Praseodymium nickelate, Pr2NiO4 (PNO), is a promising electrode to promote oxygen reduction reaction (ORR) in a solid oxide fuel cell, but it exhibits phase transformation during electrochemical operation. The origins of the simultaneous phase transformation and high electrochemical performance still remain obscure. We carried out a systematic density functional theory study to elucidate the mechanism for this conjugated phenomenon. Both electronic structure/charge and normal-mode analysis suggest the presence of peroxide. Our study shows that the formation of peroxide (O22-) is attributed to both oxygen interstitials and Pr vacancies. The peroxide species limits the oxygen ion migration due to the additional energy required to break its O-O bond, which leads to a decrease in ORR activity. Subsequently, we investigate the diffusion paths of Pr-ions while comparing them with those of other Ln3+ ions (La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) in PNO. The formation energies for various Ln3+ cation occupancies are calculated, as well as segregation energies in CeO2(111) surfaces. Finally, criteria for effective Ln3+ dopants are developed. La, Nd, and Pm are proposed as potential substituents in PNO to obtain a stable structure.

Influence of Oxygen Ion Migration from Substrates on Photochemical Degradation of CH3NH3PbI3 Hybrid Perovskite

Measurements of XPS survey, core levels (N 1s, O 1s, Pb 4f, I 3d), and valence band (VB) spectra of CH3NH3PbI3 (MAPbI3) hybrid perovskite prepared on different substrates (glass, indium tin oxide (ITO), and TiO2) aged under different light-soaking conditions at room temperature are presented. The results reveal that the photochemical stability of MAPbI3 depends on the type of substrate and gradually decreases when glass is replaced by ITO and TiO2. Also, the degradation upon exposure to visible light is accompanied by the formation of MAI, PbI2, and Pb0 products as shown by XPS core levels spectra. According to XPS O 1s and VB spectra measurements, this degradation process is superimposed on the partial oxidation of lead atoms in ITO/MAPbI3 and TiO2/MAPbI3, for which Pb–O bonds are formed due to the diffusion of the oxygen ions from the substrates. This unexpected interaction leads to additional photochemical degradation.

Fast oxygen ion migration in Cu–In–oxide bulk and its utilization for effective CO2 conversion at lower temperature

Efficient activation of CO2 at low temperature was achieved by reverse water–gas shift via chemical looping (RWGS-CL) by virtue of fast oxygen ion migration in a Cu–In structured oxide, even at lower temperatures.

First-Principles Studies of Oxygen Ion Migration Behavior for Different Valence B-site Ions Doped SrFeO3-δ Ceramic Membrane

Density functional theory calculations were performed to investigate the structural, electronic, and oxygen ion migration properties of B-site ions doped SrFeO3-δ perovskite (B = Al, Zr, Nb, and W) materials,...

Facilitating room-temperature oxygen ion migration via Co-O bond activation in cobaltite films

Oxygen ion migration in strongly correlated oxides can elicit dramatic changes in crystal structure, chemical and magnetoelectric properties, which holds promising for wide applications in catalysis, energy conversion, and electronics....

Investigation of the Resistive Switching Mechanisms and Rectification Characteristics of HfO2-Based Resistive Random Access Memory Devices with Different Electrode Materials

To study the substitutability of noble metal electrodes in memristors, the effect of Pt/HfO2/Ti structure on the replacement of noble metal electrode Pt by different electrodes was studied. Compared with the unsubstituted devices, the HfO2-based RRAM devices with TiN and TiOxNy electrodes devices showed good resistive switching performance and resistive switching mechanism under oxygen ion migration. Five devices were prepared, and their resistive switching mechanism under oxygen ion migration was investigated. Moreover, besides the resistive switching phenomenon of these RRAM devices, it was found that significant rectifying characteristics were exhibited in a highresistance state (HRS). This phenomenon can be explained by regulation of the Schottky barrier of the interface between the top electrode and the resistive layer, which can be influenced by the migration of oxygen vacancies.

Fast Oxygen Ion Migration in Cu–In–oxide Bulk and Its Utilization for Effective CO2 Conversion at Lower Temperature

Efficient activation of CO₂ at low temperature was achieved by reverse water–gas shift <i>via</i> chemical looping (RWGS‑CL) by virtue of fast oxygen ion migration in Cu–In–structured oxide, even at lower temperatures. Results show that novel Cu–In₂O₃ structured oxide can show a remarkably higher CO₂ splitting rate than ever reported. Various analyses revealed that RWGS‑CL on Cu–In₂O₃ is derived from redox between Cu–In₂O₃ and Cu<i>_x</i>In<i>_y</i> alloy. Key factors for high CO₂ splitting were fast migration of oxide ions in alloy and the preferential oxidation of the interface of alloy–In₂O₃ in the bulk of the particles. The findings reported herein can open up new avenues to achieve effective CO₂ conversion at lower temperatures.

Fast Oxygen Ion Migration in Cu–In–oxide Bulk and Its Utilization for Effective CO2 Conversion at Lower Temperature

Efficient activation of CO₂ at low temperature was achieved by reverse water–gas shift <i>via</i> chemical looping (RWGS‑CL) by virtue of fast oxygen ion migration in Cu–In–structured oxide, even at lower temperatures. Results show that novel Cu–In₂O₃ structured oxide can show a remarkably higher CO₂ splitting rate than ever reported. Various analyses revealed that RWGS‑CL on Cu–In₂O₃ is derived from redox between Cu–In₂O₃ and Cu<i>_x</i>In<i>_y</i> alloy. Key factors for high CO₂ splitting were fast migration of oxide ions in alloy and the preferential oxidation of the interface of alloy–In₂O₃ in the bulk of the particles. The findings reported herein can open up new avenues to achieve effective CO₂ conversion at lower temperatures.