On the high structural heterogeneity of Fe impregnated graphite-carbon catalysts from Fe nitrate precursor

Arrigo, R; Schuster, ME

Abstract

Wet impregnation is broadly applied for the synthesis of carbon supported metal/metal oxide nanostructures because of its high flexibility, simplicity and low cost. By contrast, impregnated catalysts are typified by a usually undesired nanostructural and morphological heterogeneity of the supported phase resulting from a poor stabilization at the support surface. This study on graphite-supported Fe based materials from Fe nitrate precursor is concerned with the understanding of the chemistry that dictates during the multi-step synthesis, which is key to designing structurally homogeneous catalysts. By means of core level X-ray photoelectron spectroscopy, near edge X-ray absorption fine structure spectroscopy and atomic resolution electron microscopy, we not only found a large variety of particles sizes and morphologies but also chemical phases. Herein, thermally stable single atoms and few atoms clusters are identified together with large agglomerates of an oxy-hydroxide ferrihydrite-like phase. Moreover, the thermally induced phase transformation of the initially poorly ordered oxy-hydroxide phase into several oxide phases is revealed, together with the existence of thermally stable N impurities retained in the structure as Fe-N-O bonds. The nature of the interactions with the support and the structural dynamics induced by the thermal treatment rationalize the high heterogeneity observed in these catalysts.

Citation

Arrigo, R., & Schuster, M. (2019). On the high structural heterogeneity of Fe impregnated graphite-carbon catalysts from Fe nitrate precursor. Catalysts, 9(4), 303. https://doi.org/10.3390/catal9040303

• Journal Article Type: Article
• Acceptance Date: Mar 25, 2019
• Online Publication Date: Mar 27, 2019
• Publication Date: Mar 27, 2019
• Deposit Date: Mar 26, 2019
• Publicly Available Date: Mar 29, 2019
• Journal: Catalysts
• Publisher: MDPI
• Volume: 9
• Issue: 4
• Pages: 303
• DOI: https://doi.org/10.3390/catal9040303
• Publisher URL: https://doi.org/10.3390/catal9040303
• Related Public URLs: https://www.mdpi.com/journal/catalysts