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Based on the data of thin section, scanning electron microscope, X-ray diffraction of clay minerals, formation water and physical property parameters, we systematically analyzed the petrology, and formation water of the Lower Jurassic The Formation sandstone in the Yiqikeiike Structural Belt of Kuqa Depression, Tarim Basin, combined with the thermal-burial history and the distribution law of fractures and faults of the Ahe Formation in the Yiqikelike Structural Belt, the sealing characteristics of diagenetic fluid, and the oil and gas preservation conditions of the The Formation sandstone reservoirs in the axis and limb of Yiqikelike Anticline are discussed. The results show that volume fraction of authigenic kaoiinite in the Ahe Formation sandstone is relatively high in the aniline axis, but relatively low in the limb. The difference of dlagenetic evolution sequence between the axis and limb of the Yiqikelike Anticline is about 5 Ma ago. Compared with the antilime limb, the sodium chloride coefficient and desulfurization coefficient in the formation water of Ahe Formation in the anticline axis are higher, and the metamorphic coefficient is lower; the sealing property of dlagenetic and system of the Ahe Formation sandstone in the anticline axis is weaker than that in the anticline limb, which affects the accumulation of natural gas. The results have great significance for predicting the distribution of oil and gas reservoirs in Yqqikelike Structural Belt. [ABSTRACT FROM AUTHOR]

Pt-group metal (PGM)-free catalysts of the Me–N–C type based on abundant and inexpensive elements have gained importance in the field of oxygen reduction reaction (ORR) electrocatalysis due to their promising ORR-activities. Their insufficient stability, however, has fueled the interest in obtaining an in-depth understanding of their composition, which requires highly sensitive techniques compatible with their low metal contents (typically <5 wt%). In the particular context of iron-based materials, 57Fe-Mössbauer spectroscopy is often used to provide such compositional information, but requires (partially) 57Fe-enriched precursors. As a consequence, the extrapolation of conclusions drawn from Mössbauer measurements on 57Fe-enriched catalysts to equivalent materials with the standard isotope distribution relies on the assumption that the metal precursor's isotopic profile does not affect the catalysts' composition and ORR-activity. To verify this hypothesis, in this study we prepared two series of Fe-based catalysts using distinctively different synthesis approaches and various relative contents of 57Fe-enriched precursors, and observed that the extent of the latter parameter significantly affected the catalysts' ORR-activity. This effect was successfully correlated with the Fe-speciation of the catalysts inferred from the characterization of these samples with Mössbauer and X-ray absorption spectroscopies. Ultimately, these results highlight the crucial importance of verifying the consistency of the catalysts' activity and composition upon comparing standard and 57Fe-enriched samples. [ABSTRACT FROM AUTHOR]

Perovskite oxides with mixed ionic and electronic conductivities are very promising candidates for their application as energy materials related to fuel cell and metal air battery integration. In this article, we report on the systematic characterization of mixed proton and electron conducting compounds of composition BaFe1−xCoxO3−y−δ(OH)y synthesized via nebulized spray pyrolysis. Independent of the value of x, all samples BaFe1−xCoxO3−y−δ(OH)y were found to crystallize in an orthorhombic ordering/distortion variant of the perovskite type structure (space group Cmcm) and are isotypic to the border phases (x = 0 or 1) reported previously. A minimum water content was observed for the composition with x = 0.5, which increases steadily for Co or Fe richer compositions. Impedance studies show that the conductivity increases with increasing Co-content, with BaCo0.5Fe0.5O2.07(OH)0.74 showing a total electrical conductivity of 10−7 S cm−1 at 298 K, an order of magnitude higher than found for BaFeO2.33(OH)0.33. Further, bifunctional catalytic activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was found for the compounds of the series as investigated in 0.1 M KOH, with BaFe0.8Co0.2O3−y−δ(OH)y possessing the best bifunctional performance parameter of ΔU = 1.10 V, which is comparable to that of other non-precious metal catalysts. [ABSTRACT FROM AUTHOR]

In this work, the effect of porphyrin loading and template size is varied systematically to study its impact on the oxygen reduction reaction (ORR) activity and selectivity as followed by rotating ring disc electrode experiments in both acidic and alkaline electrolytes. The structural composition and morphology are investigated by 57 Fe Mössbauer spectroscopy, transmission electron microscopy, Raman spectroscopy and Brunauer-Emmett-Teller analysis. It is shown that with decreasing template size, specifically the ORR performance towards fuel cell application gets improved, while at constant area loading of the iron precursor (here expressed in number of porphyrin layers), the iron signature does not change much. Moreover, it is well illustrated that too large area loadings result in the formation of undesired side phases that also cause a decrease in the performance, specifically in acidic electrolyte. Thus, if the impact of morphology is the focus of research it is important to consider the area loading rather than its weight loading. At constant weight loading, beside morphology the structural composition can also change and impact the catalytic performance. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.

Pt-group metal (PGM)-free catalysts of the Me-N-C type based on abundant and inexpensive elements have gained importance in the field of oxygen reduction reaction (ORR) electrocatalysis due to their promising ORR-activities. Their insufficient stability, however, has fueled the interest in obtaining an in-depth understanding of their composition, which requires highly sensitive techniques compatible with their low metal contents (typically <5 wt%). In the particular context of iron-based materials, 57Fe-Mössbauer spectroscopy is often used to provide such compositional information, but requires (partially) 57Fe-enriched precursors. As a consequence, the extrapolation of conclusions drawn from Mössbauer measurements on 57Fe-enriched catalysts to equivalent materials with the standard isotope distribution relies on the assumption that the metal precursor's isotopic profile does not affect the catalysts' composition and ORR-activity. To verify this hypothesis, in this study we prepared two series of Fe-based catalysts using distinctively different synthesis approaches and various relative contents of 57Fe-enriched precursors, and observed that the extent of the latter parameter significantly affected the catalysts' ORR-activity. This effect was successfully correlated with the Fe-speciation of the catalysts inferred from the characterization of these samples with Mössbauer and X-ray absorption spectroscopies. Ultimately, these results highlight the crucial importance of verifying the consistency of the catalysts' activity and composition upon comparing standard and 57Fe-enriched samples.

This work addresses the importance of Mössbauer spectroscopy for the characterization of iron-containing electrocatalysts. The most important aspects of electrocatalysis and Mössbauer spectroscopy are summarized. Next, Fe-N-C catalysts and important conclusions made by this technique on preparation, active site identification and degradation are summarized. Furthermore, recent highlights derived for other iron-containing electrocatalysts are summarized., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)