Pyrolysis behaviour of metalloporphyrins. Part 2.—A mössbauer study of pyrolysed Fe^IIItetraphenylporphyrin chloride

Abstract

Fe"' tetraphenylporphyrin chloride (FeCITPP) has been pyrolysed at different temperatures (450-850 "C) for different lengths of time (10-260 min). Some of the samples were mixed with carbon black in a 50/50 (w/w) proportion. Mossbauer spectra were obtained for these catalyst powders. The spectra reveal a number of different sites, occurring with different relative abundance depending on the pretreatment. XPS and electrochemical measurements have also been performed using the same samples. The electrocatalytic properties can be described as a function of the abundance of the various sites and the XPS data were used to support the interpretation.

Elucidating the Structural Composition of an Fe–N–C Catalyst by Nuclear‐ and Electron‐Resonance Techniques

“…First, we would like to discuss the structural composition of the catalyst as derived by Mössbauer spectroscopy at RT (Figure b), scanning transmission electron microscopy (STEM) (c), and EPR spectroscopy at K (d). The Mössbauer spectrum looks very similar to other porphyrin‐based catalysts prepared at low pyrolysis temperature . It was fitted with three iron sites, all assigned to doublet species.…”

Graphene-supported metal single-atom catalysts: a concise review

“…The substrates of supported catalysts can be divided into traditional metal substrate, metal oxide substrate and new 2D material substrate. Many outstanding active metals of SACs, such as Pt [56,57], Au [58], Pd [59], Fe [60][61][62], Co [63][64][65], Ni [66] and Cr [67], have exhibited extraordinary activity in many catalytic reactions. There are also some common metal-oxide supporting substrates of SACs, such as FeO x [5], TiO 2 [68], ZrO 2 [69] and ZnO [70].…”

Experimental and theoretical modeling of Fe-, Co-, Cu-, Mn-based electrocatalysts for oxygen reduction

“…XPS (data not shown in this work) was helpful in confirming the nature of nitrogen in the catalytic centers, but turned out to be too insensitive for reliable measurements of metal concentrations in catalysts after treatment with acid for high performance. Mössbauer Spectroscopy of Co/Fe/S shows next to Doublet 1 two more doublets in contrast to the asymmetric doublet related to iron porphyrins, but the determined structure is similar to other porphyrin based heat treated catalysts [9], and materials with a MN x structure [30]. Theoretical research and model experiments will be required to find out more about the nature of these centers.…”