The electrochemical conversion of small organic molecules to value-added chemicals and hydrogen/electricity without CO2 emissions integrates efficient energy conversions (hydrogen energy or electricity) and value-added chemical productions in one reaction system, which is essentially competitive in the carbon-neutral era. However, the activity, stability, and cost-effectiveness of electrocatalysts, as well as the safety, durability, and scalability of devices, are still challenging for their industrial applications. In addition, a lack of knowledge about relevant and detailed mechanisms restricts the further development of electrocatalysts and devices. A timely review of the electrocatalysts, devices, and mechanisms is essential to shed lights on the correct direction towards further development. In this review, the advances in the design of electrocatalysts, fabrication of devices, and understanding of reaction mechanisms are comprehensively summarized and analyzed. The major challenges are also discussed as well as the potential approaches to overcoming them. The insights for further development are provided to offer a sustainable and environmentally friendly approach to cogeneration of energy and chemicals production.
Abstract The electrolyte/anode interface in solid oxide fuel cells with La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3–δ electrolytes and composite anodes containing La 0.8 Sr 0.2 Cr 0.82 Ru 0.18 O 3–δ and Ce 0.9 Gd 0.1 O 2–δ (GDC) was studied using transmission electron microscope Z‐contrast imaging and energy dispersive X‐ray spectroscopy. The anode/electrolyte interface of an operated cell had numerous defective regions in the electrolyte, immediately adjacent to anode GDC particles. These areas had a different chemical composition than other electrolyte regions and were crystallographically inhomogeneous. These regions were not observed in a cell reduced in hydrogen that was not operated, suggesting that they were the result of combined electrical and chemical potential gradients present during cell operation. Ru nanoparticles were observed on the chromite surfaces of the operated.
Two-dimensional (2D) dopant profiles, in the range of to , in laser-diffused silicon resistors were obtained using dopant selective etching (DSE) in combination with cross-sectional transmission electron microscopy (TEM) and focused ion beam technique. Compared with conventional DSE/TEM dopant evaluation, the properties of this technique, related to the reliability, reproducibility, and accuracy of quantification of dopant concentration from to , have been improved by considering a vector instead of a scalar etching rate, as determined by an etching model and by a novel calibration method. Those evaluated profiles were accurately compared with a numerical simulation based on heat-transfer and diffusion equations.
Solid oxide cells (SOCs) are regarded as a promising energy technology due to their large current density, diverse range of fuels, and high energy conversion efficiency. The double perovskite Sr2FeMoO6 (SFM) has attracted considerable attention for SOCs due to its tunable structure with superior performance of high conductivity, excellent thermal stability, and remarkable carbon deposition resistance in a reducing atmosphere. However, the electrocatalytic activity of SFM is considerably lower than that of commercial Ni-based SOC electrodes. A timely summary of the synthesis, modulation, and application of SFM perovskites is of great significance for its further development for SOCs. In this review, the methods employed in the preparation of SFM electrocatalysts are introduced first. Then, the advancements in the application of different SFM-based electrocatalysts in the field of SOCs are reviewed, and the research progress in the in situ exsolution of SFM-based electrocatalysts through ion regulation is assessed. Finally, the future issues associated with SFM-based electrocatalysts are addressed in the realm of electrocatalysis, to advance their application.
Abstract Sr 2 Fe 1.5 Mo 0.5 O 6‐δ (SFM) perovskite oxide is one of the most promising materials for solid oxide fuel cells (SOFCs) anode. However, the low catalytic activity is a major roadblock that obstructs its practical applications. Although in situ exsolution of B‐site metals is demonstrated as a promising approach to enhancing its performance, it can easily induce the co‐segregation of A‐site Sr, which seriously deteriorates the performance stability. In this work, the A‐site Sr element in SFM is partially replaced by Pr, while B‐site Mo is partially replaced by Ni. The in situ co‐exsolution of both FeNi alloy and PrO x nanoparticles on the reduced Pr 0.8 Sr 1.2 Fe 1.5 Mo 0.3 Ni 0.2 O 6‐δ (R‐PSFMN) perovskite is successfully achieved. It is found that the peak power densities (P max ) of the single cell using R‐PSFMN as the anode reaches as high as 2.29, 1.60, 1.07, and 0.67 W cm − 2 in H 2 atmosphere at the operating temperatures of 850, 800, 750 and 700 °C, respectively. Furthermore, it also exhibits excellent performance stability and anticoke properties when using ethane as fuel. The impregnation experiment further corroborates that the improved performance and stability are partly attributable to the contribution of PrO x nanoparticles, presenting a promising approach to enhance the electrochemical performance of SOFC perovskite anodes.
Fe/Fe oxide nanoparticles, in which the core consists of metallic Fe and the shell is composed of Fe oxides, were obtained by reduction of an aqueous solution of FeCl3 within a NaBH4 solution, or, using a water-in-oil micro-emulsion with CTAB as the surfactant. The reduction was performed either in an inert atmosphere or in air, and passivation with air was performed to produce the Fe/Fe3O4 core/shell composite. Phase identification and particle size were determined by X-ray diffraction and TEM. Thermal analysis was performed using a differential scanning calorimeter. The quasistatic magnetic properties were measured using a VSM, and the specific absorption rates (SARs) of both Fe oxide and Fe/Fe3O4 composite nanoparticles either dispersed in methanol or in an epoxy resin were measured by Luxtron fiber temperature sensors in an alternating magnetic field of 150 Oe at 250 kHz. It was found that the preparation conditions, including the concentrations of solutions, the mixing procedure and the heat treatment, influence the particle size, the crystal structure and consequently the magnetic properties of the particles. Compared with Fe oxides, the saturation magnetization (MS) of Fe/Fe3O4 particles (100-190 emu/g) can be twice as high, and the coercivity (HC) can be tunable from several Oe to several hundred Oe. Hence, the SAR of Fe/Fe3O4 composite nanoparticles can be much higher than that of Fe oxides, with a maximum SAR of 345 W/g. The heating behavior is related to the magnetic behavior of the nanoparticles.
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