Examination of the Bonding in Binary Transition-Metal Monophosphides MP (M = Cr, Mn, Fe, Co) by X-Ray Photoelectron Spectroscopy

Abstract

The binary transition-metal monophosphides CrP, MnP, FeP, and CoP have been studied with X-ray photoelectron spectroscopy. The shifts in phosphorus 2p(3/2) core line binding energies relative to that of elemental phosphorus indicated that the degree of ionicity of the metal-phosphorus bond decreases on progressing from CrP to CoP. The metal 2p(3/2) core line binding energies differ only slightly and show similar line shapes to those of the elemental metals, reaffirming the notion that these transition-metal phosphides have considerable metallic character. The satellite structure observed in the Co 2p(3/2) X-ray photoelectron spectra of Co metal and CoP was examined by reflection electron energy loss spectroscopy and has been attributed to plasmon loss, not final state effects as has been previously suggested. Valence-band spectra of the transition-metal phosphides agree well with the density of states profiles determined from band structure calculations. The electron populations of the different electronic states were extracted from the fitted valence-band spectra, and these confirm the presence of strong M-P and weak P-P bonding interactions. Atomic charges determined from the P 2p core line spectra and the fitted valence-band spectra support the approximate formulation M(1+)P(1-) for these phosphides.

Ferric phosphide nanoparticles film supported on titanium plate: A high-performance hydrogen evolution cathode in both acidic and neutral solutions

“…The high-resolution P(2p) region shows two peaks at 130.3 and 129.5 eV reflecting the BE of P 2p 1/2 and P 2p 3/2 , respectively, along with one peak at 133.6 eV. The peaks at 707.4 and 129.5 eV are close to the BE for Fe and P in FeP [36]. The peaks at 711.9 and 133.6 eV can be assigned to oxidized Fe and P species arising from superficial oxidation of FeP exposed to air [37].…”

Phase‐Controlled Synthesis of Transition‐Metal Phosphide Nanowires by Ullmann‐Type Reactions

“…The results are consistent with the previous observations that the P 2p region of transition-metal phosphides usually splits into two peaks for P 2p 1/2 and P 2p 3/2 in highresolution XPS spectra. [17] The peak centered at 133.93 eV corresponds to P 2p from oxidized P. The presence of oxidized P species in the samples is probably due to two processes: separation of product in air after the reaction, which can lead to surface oxidization of nanoscale phosphides due to absorbed gaseous molecules indicated by the close-up oxygen XPS spectrum, which are often observed in nanomaterials, [16b] and oxidization of phosphides by residual oxygen in the sealed tube during reaction.…”

Electromagnetic properties and electronic structure of the iron-based layered superconductor LaFePO

“…Therefore, paramagnetism of itinerant electrons is dominant in 8 the normal conducting states, although Van Vleck paramagnetism due to orbital moments and the more negligible core electron diamagnetism may contribute to the observed susceptibility. [43] and Fe-P inter-metallic compounds (FeP [44] and LaFe 4 P 12 [45]). On the other hand, it is distinctly different from those of FeO [46] and FeS 2 [35], suggesting that the Fe-P chemical bond in LaOFeP has less of an ionic nature and is more likely to be metallic or covalent.…”