Exfoliablity, magnetism, energy storage and stability of metal thiophosphate nanosheets made in liquid medium

Abstract

The family of antiferromagnetic layered metal hexathiohypo diphosphates, M2P2S6 represents a versatile class of materials, particularly interesting for fundamental studies on magnetic properties in low dimensional structures, and yet exhibiting great potential for a broad variety of applications including catalysis, energy storage and conversion, and spintronics. In this work, three representatives of this family of 2D materials (M = Fe, Ni, and Mn) are exfoliated in the liquid phase under inert conditions and the nanosheet’s properties are studied in detail for different sizes of all three compounds. Centrifugation-based size selection is performed for this purpose. The exfoliability and structural integrity of the nanosheets is studied by statistical AFM and TEM measurements. Further, we report size and thickness dependent optical properties and spectroscopic metrics for the average material dimensions in dispersion, as well as the nanomaterials’ magnetic response using a combination of cryo-Raman and SQUID measurements. Finally, the material stability is studied semi-quantitatively, using time and temperature dependent extinction and absorbance spectroscopy, enabling the determination of the materials’ half-life, portion of reacted substance and the macroscopic activation energy for the degradation.

Solution-Processed NiPS3 Thin Films from Liquid Exfoliated Inks with Long-Lived Spin-Entangled Excitons

“…However, the emission already disappears at approximately 100 K, which is below the Neél temperature of LPE NiPS 3 confirmed by our previous study. 51 Thus, we identify an additional effect from thermal heating on the excitonic luminescence in LPE NiPS 3 , beyond the reported connection to the presence of antiferromagnetic order. The blue shift of the subpeaks (A, B, and C see Supporting Information Figure 6a) upon cooling is typical of the temperature-dependent bandgap energy 52 change in semi-conductors.…”

“…The luminescence from Peak I vanishes as temperature increases (Figure c and Supporting Information Figure 6a), which is in line with previous reports and can be considered as a result of the antiferromagnetic-to-paramagnetic phase change in the NiPS 3 thin films. However, the emission already disappears at approximately 100 K, which is below the Néel temperature of LPE NiPS 3 confirmed by our previous study . Thus, we identify an additional effect from thermal heating on the excitonic luminescence in LPE NiPS 3 , beyond the reported connection to the presence of antiferromagnetic order.…”

Structural Transformations in Few-Layer MnPSe3 Stimulated by Thermal Annealing and Electron Irradiation

“…As an example, pressure-driven compression has been reported to change the magnetic properties, as well as to cause transitions from a semiconductor to a metal in MnPS 3 and MnPSe 3 . 63,64 Moreover, several TEM studies 60,62,65,66 on fewlayer TMPTs proved that few-layer TMPTs can be successfully prepared. Furthermore, strong modifications of the structure and properties of few-layer transition metal phosphorus trisulfides caused by electron irradiation were reported.…”

“…Theoretical and experimental studies showed the possibility of tailoring the properties of these materials by different stimuli. As an example, pressure-driven compression has been reported to change the magnetic properties, as well as to cause transitions from a semiconductor to a metal in MnPS 3 and MnPSe 3 . , Moreover, several TEM studies ,,, on few-layer TMPTs proved that few-layer TMPTs can be successfully prepared. Furthermore, strong modifications of the structure and properties of few-layer transition metal phosphorus trisulfides caused by electron irradiation were reported. ,, A predominant removal of sulfur in few-layer TMPTs by electron irradiation in the low-voltage regime (i.e., 30–80 kV) in TEM was observed. ,, Calculations revealed that the elastic knock-on displacement threshold of S is significantly lower compared to, for instance, MoS 2 or MoSe 2 . , Thus, elastic damage plays a significant role in investigating transition metal phosphorus trisulfides in TEM above 50 kV. , Further, inelastic damage channels cause the primary removal of S in TMPTs as well below the knock on threshold .…”

“…Promising 2D materials with interesting properties are transition metal phosphorus trichalcogenides (TMPTs). − They display a wide variety of band gaps, , ranging from 1.3 to 3.5 eV, , and their constituent chemical elements are mostly earth-abundant and nontoxic, making them suitable candidates for distinct optoelectronic applications. , In particular, TMPTs exhibit inherent magnetic properties . They are among the most recently studied 2D antiferromagnetic materials − because the magnetism persists to the limit of only a few layers, , suggesting them as test objects for studying the fundamental aspects of 2D magnetism. , In addition, TMPTs are excellent candidates for intercalation by ions or molecules, which makes them suitable materials for energy storage applications. − Particularly, applications of TMPTs as anode materials in Li-ion batteries have already been proposed due to the high binding energy of Li on their surface. , Here, it has to be noted that TMPTs can be susceptible to oxidation. − For instance, for MnPSe 3 it was shown that mainly Mn and also P oxidize during exposure to the air …”