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CeO2-based surface modification is established as an effective strategy for improving the electrochemical performance of solid oxide electrolysis cells (SOECs), but the relevant mechanism has not been fully explored yet. Here, we employ focused ion beam-scanning electron microscopy to examine the microstructural evolution of bare nickel-based yttrium-stabilized zirconia (Ni/YSZ) electrode (reference cell) and Gd-doped CeO2 (CGO)-infiltrated Ni/YSZ electrode (optimized cell) before and after 100-h durability test. The initial current density of the optimized cell was 1.16 A cm−2 (at 1.3 V), which was 1.5 times larger than that of the reference cell. The voltage of the reference cell degraded dramatically due to a 1.16% reduction in the volume fraction of Ni, while the optimized cell showed a negligible degradation with a minor change in the volume fraction of Ni. It was confirmed that CGO nanoparticles formed a protective layer on the Ni surface during the electrolysis process, which prevented further evaporation of Ni. Overall, the infiltration of CGO into traditional Ni/YSZ electrode prevented decrease in the triple-phase boundary density and reduced the resistance by providing additional active sites for hydrogen evolution reaction. We believe that this work provides an efficient strategy for developing high-performance and long-term stable SOECs.

By first applying a thorium-organic framework (Th-SINAP-2) as a radiation attenuator and by incorporating a terpyridine derivative (Htpbz) as a photo-responsive guest, selective photochromism in response to X-rays was achieved in the host-guest assembly of Htpbz@Th-SINAP-2. Such a combination endows the afforded material with the lowest detection limit of X-ray dose among all photochromic sensors and a brand-new function of X-ray dosimetry for thorium containing materials.

A novel molten salt method was employed to synthesize 10% Nb doped La0.6Sr0.4FeO3−δ (LSFN). The as-synthesized powders were pure and adopted a porous structure. Using LSFN as the oxygen electrode for a reversible solid oxide cell, the button cell exhibited a peak power density of 0.79 W cm−2 in H2 and an electrolysis current density of 0.89 A cm−2 at 1.3 V in 50% CO2/50% H2 at 800 °C. A large fraction of Fe2+ was found in LSFN, resulting in the improved performance. Our results indicate that the molten salt method is a promising approach for the synthesis of highly active perovskite electrode with a dopant of Nb.

High-temperature (700-900 degrees C) steam electrolysis based on solid oxide electrolysis cells (SOECs) is valuable as an efficient and clean path for large-scale hydrogen production with nearly zero carbon emissions, compared with the traditional paths of steam methane reforming or coal gasification. The operation parameters, in particular the feeding gas composition and pressure, significantly affect the performance of the electrolysis cell. In this study, a computational fluid dynamics model of an SOEC is built to predict the electrochemical performance of the cell with different sweep gases on the oxygen electrode. Sweep gases with different oxygen partial pressures between 1.01 x 10(3) and 1.0 x 10(5) Pa are fed to the oxygen electrode of the cell, and the influence of the oxygen partial pressure on the chemical equilibrium and kinetic reactions of the SOECs is analyzed. It is shown that the rate of increase of the reversible potential is inversely proportional to the oxygen partial pressure. Regarding the overpotentials caused by the ohmic, activation, and concentration polarization, the results vary with the reversible potential. The Ohmic overpotential is constant under different operating conditions. The activation and concentration overpotentials at the hydrogen electrode are also steady over the entire oxygen partial pressure range. The oxygen partial pressure has the largest effect on the activation and concentration overpotentials on the oxygen electrode side, both of which decrease sharply with increasing oxygen partial pressure. Owing to the combined effects of the reversible potential and polarization overpotentials, the total electrolysis voltage is nonlinear. At low current density, the electrolysis cell shows better performance at low oxygen partial pressure, whereas the performance improves with increasing oxygen partial pressure at high current density. Thus, at low current density, the best sweep gas should be an oxygen-deficient gas such as nitrogen, CO2, or steam. Steam is the most promising because it is easy to separate the steam from the by-product oxygen in the tail gas, provided that the oxygen electrode is humidity-tolerant. However, at high current density, it is best to use pure oxygen as the sweep gas to reduce the electric energy consumption in the steam electrolysis process. The effects of the oxygen partial pressure on the power density and coefficient of performance of the SOEC are also discussed. At low current density, the electrical power demand is constant, and the efficiency decreases with growing oxygen partial pressure, whereas at high current density, the electrical power demand drops, and the efficiency increases.

© 2020 Elsevier B.V. Molten salts are a unique type of electrolyte enabling high-temperature electrochemical energy storage (EES) with unmatched reversible electrode kinetics and high ion-conductivities, and hence impressive storage capacity and power capability. However, their high tendency to evaporate and flow at high temperatures challenges the design and fabrication of the respective EES devices in terms of manufacturing cost and cycling durability. On the other hand, most of these EES devices require lithium-containing molten salts as the electrolyte to enhance performances, which not only increases the cost but also demands a share of the already limited lithium resources. Here we report a novel quasi-solid-state (QSS) electrolyte, consisting of the molten eutectic mixture of Na2CO3-K2CO3 and nanoparticles of yttrium stabilized zirconia (YSZ) in a mass ratio of 1:1. The QSS electrolyte has relatively lower volatility in comparison with the pristine molten Na2CO3-K2CO3 eutectic, and therefore significantly suppresses the evaporation of molten salts, thanks to a strong interaction at the interface between molten salt and YSZ nanoparticles at high temperatures. The QSS electrolyte was used to construct an iron-air battery that performed excellently in charge-discharge cycling with high columbic and energy efficiencies. We also propose and confirm a redox mechanism at the three-phase interlines in the negative electrode. These findings can help establish a simpler and more efficient approach to designing low-cost and high-performance molten salt metal-air batteries with high stability and safety.

Targeted synthesis, through a heteroleptic methodology, has resulted in three types of lanthanide (Ln) coordination polymers (CPs) with tailored dimensionality, tunable photoluminescent colors, and distinct luminescence quenching upon UV and X-ray irradiation. The homoleptic Ln(tpbz)(NO

Exploring high-performance electrocatalysts for the oxygen evolution reaction (OER) is pivotal for renewable energy storage and conversion. The surface self-reconstruction during the OER is considered as the key of highly active catalysts, whereas identifying the local electronic and geometric structure of the reconstruction-derived components is challenging. Herein, an in situ exsolution method towards the typical LaCo0.8Fe0.2O3−δ perovskite is developed to obtain a new type of lanthana-anchored CoFe catalyst. The optimized catalyst exhibits a low overpotential of 293 mV to reach the current density of 10 mA cm−2 in 0.1 M KOH. Most importantly, operando X-ray absorption spectroscopy (XAS) measurements demonstrate that the CoFe species in the catalyst are nearly transformed into unique (Co/Fe)O(OH) with a definite coordination-unsaturated structure under electrochemical conditions, which actually contributes to this superior performance. Moreover, the presence of the lanthana support promotes this transformation. Our work not only suggests a facile reconstructive strategy to dramatically enhance the OER activity of perovskite oxides in alkaline media, but also unravels the fine structure of true active sites through operando X-ray spectroscopic tracking.