Developing cost effective electrocatalysts with high oxygen evolution reaction (OER) activity is essential for large‐scale application of many electrochemical energy systems. Although the impacts of either lattice strain or oxygen defects on the OER performance of oxide catalysts have been extensively investigated, the effects of both factors are normally treated separately. In this work, the coupled effects of both strain and oxygen deficiency on the electrocatalytic activity of La 0.7 Sr 0.3 CoO 3−δ (LSC) thin films grown on single crystal substrates (LaAlO3 (LAO) and SrTiO3 (STO)) are investigated. Electrochemical tests show that the OER activities of LSC films are higher under compression than under tension, and are diminished as oxygen vacancies are introduced by vacuum annealing. Both experimental and computational results indicate that the LSC films under tension (e.g., LSC/STO) have larger oxygen deficiency than the films under compression (e.g., LSC/LAO), which attribute to smaller oxygen vacancy formation energy. Such strain‐induced excessive oxygen vacancies in the LSC/STO increases the e g state occupancy and enlarges the energy gap between the O 2p and Co 3d band, resulting in lower OER activity. Understanding the critical role of strain–defect coupling is important for achieving the rational design of highly active and durable catalysts for energy devices.

Yttrium-doped barium zirconate (BZY) has emerged as an attractive candidate of oxygen ion (O2–) conducting solid electrolyte because of its high ionic conductivity and excellent chemical stability. In this work, the O2– transport properties and mechanisms of BZY coexisting oxygen vacancies, dopants, and edge dislocations are simulated by reactive molecular dynamics for the first time, and the yttrium concentration (Y%) and temperature (T) dependences of thermodynamic and kinetic properties are studied for the bulk and dislocation (Bulk and Disl) systems, respectively. It is concluded that the Y% under 20 mol % for Bulk BZY can promote O2– conduction, while 30 mol % Y-doped Disl BZY has the highest O2– diffusion coefficient. Besides, dislocations will accelerate O2– diffusion when T is less than 1173.15 K due to the formation of double-bottle diffusion channels that enables facile reorientation of oxygen polyhedron. Therefore, it is feasible to introduce line defects to enhance ion conductivity at low temperature in the practical applications of BZY electrolytes.

No abstract

LaCrO 3 -based ceramic interconnects (ICs) are currently employed in tubular solid oxide cells (SOCs), but they are facing challenges in manufacturability, durability, and cost, primarily due to Cr volatilization issues. Development of Cr-free, easy-to-manufacture, and low-cost ceramic ICs are, therefore, highly desirable for tubular SOCs. Here we report a systematic study on the chemical and physical properties of Cr-free, Y-and Nb-doped SrTiO 3−δ (Sr 1−x Y x Ti 1−y Nb y O 3 , SYTN, 0 ≤ x, y ≤ 0.1) as a ceramic IC. While similar systems have been studied in the literature, our study has focused on optimizing SYTN compositions, examining chemical compatibility between SYTN and anode substrate, fabricating bilayer structure, cosintering it with anode substrate, and testing its performance under practical oxidizing−reducing dual atmospheres. The results show that SYTN(Y 0.08 Nb 0.02 ) is the best composition as an IC since it exhibits high electrical conductivity and can be cosintered with Ni-YSZ anode substrate into a dense microstructure without any chemical reactions. A first-principles theoretical study reveals that Yand Nb-doping transforms semiconducting SrTiO 3 into itinerant large-polarons metal, confirming the high electrical conductivity. A bilayer IC consisting of La 0.8 Sr 0.2 MnO 3−δ (LSM) top-layer and SYTN(Y 0.08 Nb 0.02 ) underlayer cosintered on the anode substrate is also demonstrated with dense microstructure, low area specific resistance and negligible oxygen permeability. Overall, the cosintered bilayer ceramic IC is a promising candidate for next-generation durable, and low-cost tubular SOCs.

Nanoparticle (NP) exsolution from perovskite-based oxides matrix upon reduction has emerged as an ideal platform for designing highly active catalysts for energy and environmental applications. However, the mechanism of how the material characteristics impacts the activity is still ambiguous. In this work, taking Pr0.4Sr0.6Co0.2Fe0.7Nb0.1O3 thin film as the model system, we demonstrate the critical impact of the exsolution process on the local surface electronic structure. Combining advanced microscopic and spectroscopic techniques, particularly scanning tunneling microscopy/spectroscopy and synchrotron-based near ambient X-ray photoelectron spectroscopy, we find that the band gaps of both the oxide matrix and exsolved NP decrease during exsolution. Such changes are attributed to the defect state within the forbidden band introduced by oxygen vacancies and the charge transfer across the NP/matrix interface. Both the electronic activations of oxide matrix and the exsolved NP phase lead to good electrocatalytic activity toward the fuel oxidation reaction at elevated temperature.