Experimental Requirements for High-Temperature Solid-State Electrochemical TEM Experiments

The ability to perform both electrochemical and structural/elemental characterization in the same experiment and at the nanoscale allows to directly link electrochemical performance to the material properties and their evolution over time and operating conditions. Such experiments can be important for the further development of solid oxide cells, solid-state batteries, thermal electrical devices, and other solid-state electrochemical devices. The experimental requirements for conducting solid-state electrochemical TEM experiments in general, including sample preparation, electrochemical measurements, failure factors, and possibilities for optimization, are presented and discussed. Particularly, the methodology of performing reliable electrochemical impedance spectroscopy measurements in reactive gases and at elevated temperatures for both single materials and solid oxide cells is described. The presented results include impedance measurements of electronic conductors, an ionic conductor, and a mixed ionic and electronic conductor, all materials typically applied in solid oxide fuel and electrolysis cells. It is shown that how TEM and impedance spectroscopy can be synergically integrated to measure the transport and surface exchange properties of materials with nanoscale dimensions and to visualize their structural and elemental evolution via TEM/STEM imaging and spectroscopy.

Advancing Electrode Properties through Functionalization for Solid Oxide Cells Application: A Review

Hydrogen energy has emerged as the only renewable which is capable of sustaining the prevalent energy crisis in conjunction with other intermittent sources. In this connection, solid oxide cell (SOC) is the most sustainable solid-state devices capable of recycling and reproducing green hydrogen fuel. It is operable in reversible modes viz, fuel cell (FC) and electrolysis cell (EC). SOC is capable of engaging multiple fuels thereby promoting carbon neutral planet. The all-solid design further augments the optimization of cost, efficiency, durability and endurance at higher temperature. Electrodes are therefore, an important component which is responsible for electrocatalytic processing of fuel and oxidant for higher recyclability of cell/stack. The present review article embarks a detailed overview on the past and present status of electrode composition, heterointerface engineering applicable for SOC's. Recent trends in electrode engineering and the possibilities for advancement in SOC is also reviewed with respect to both experimental and computational aspects.

Experimental Clarification of the RWGS Reaction Effect in H2O/CO2 SOEC Co-Electrolysis Conditions

In the present investigation, modified X-Ni/GDC electrodes (where X = Au, Mo, and Fe) are studied, in the form of half-electrolyte supported cells, for their performance in the RWGS through catalytic-kinetic measurements. The samples were tested at open circuit potential conditions in order to elucidate their catalytic activity towards the production of CO (rco), which is one of the products of the H2O/CO2 co-electrolysis reaction. Physicochemical characterization is also presented, in which the samples were examined in the form of powders and as half cells with BET, H2-TPR, Air-TPO and TGA re-oxidation measurements in the presence of H2O. In brief, it was found that the rate of the produced CO (rco) increases by increasing the operating temperature and the partial pressure of H2 in the reaction mixture. In addition, the first results revealed that Fe and Mo modification enhances the catalytic production of CO, since the 2wt% Fe-Ni/GDC and 3wt% Mo-Ni/GDC electrodes were proven to perform better compared to the other samples, in the whole studied temperature range (800–900 °C), reaching thermodynamic equilibrium. Furthermore, carbon formation was not detected.

Tensile mechanical performance of Ni–Co alloy nanowires by molecular dynamics simulation

In this present contribution, tensile mechanical properties of Ni–Co alloy nanowires with Co content from 0 to 20% were studied by molecular dynamics. The simulation results show the alloy nanowire with the Co content of 5% has the highest yield value of 9.72 GPa. In addition, more Frank dislocations were generated during the loading process to improve the performance of the alloy nanowire. The Young's modulus increases little by little from 105.68 to 179.78 GPa with the increase of Co content. Secondly, with the increase of temperature, the yield strength gradually decreases to 2.13 GPa. Young's modulus tends to decrease linearly from 170.7 GPa to 48.21 GPa. At the temperatures of 500 K and 700 K, it is easier to form Frank dislocation and Hirth dislocation, respectively, in the loading process. The peak value of the radial distribution function decreases and the number of peaks decreases, indicating the disappearance of the ordered structure. Finally, after the introduction of the surface and inner void, the yield strength of the nanowire drops about to 8.97 and 6.6 GPa, respectively, and the yield strains drop to 0.056 and 0.043. In the case of the existence of internal void, perfect dislocation and Hirth dislocation can be observed in the structure.

The addition of a little Co can promote the formation of Frank and other fixed dislocations, making the alloy system have high yield strength. The defects in nanowires accelerated the occurrence of yield behavior.

Electrochemical behavior of thin-film Sm-doped ceria: insights from the point-contact configuration

The electrochemical behavior of chemical vapor deposition (CVD) grown porous films of Sm-doped ceria (SDC) for hydrogen oxidation has been evaluated by impedance spectroscopy using a point contact geometry at a temperature of 650 °C.