High Surface Area of Polyhedral Chromia and Hexagonal Chromium Sulfide by the Thermolysis of Cyclohexylammonium Hexaisothiocyanatochromate(III) Sesquihydrate

Abstract

A new organic-inorganic hybrid salt of cyclohexylammonium hexaisothiocyanatochromate(III) sesquihydrate, (C 6 H 11 NH 3 ) 3 [Cr-(NCS) 6 ] ⋅ 3/2H 2 O, was synthesized at room-temperature by metathesis and ligand addition for the establishment of energysaving chemical synthesis approach. The formation of this new salt was confirmed by FT-IR, UV-Vis spectrophotometry, elemental microanalysis, and single-crystal X-ray diffraction. The TGA study showed low-temperature thermal stability of this salt, where chromium oxide (Cr 2 O 3 ) formed under air and chromium sulfide (Cr 2 S 3 ) under argon, as PXRD confirmed their formation as nanocrystalline. The morphological studies by SEM and TEM revealed the formation of irregular polyhedron particles of Cr 2 O 3 and of hexagonal packed layers of Cr 2 S 3 . The textural study by nitrogen physisorption disclosed the mesoporous nature and high specific surface area of Cr 2 O 3 (∼ 132 m 2 g À 1 ) and Cr 2 S 3 (∼ 241 m 2 g À 1 ). Cyclohexylammonium could act as an organic self-template for the formation of mesopores and the high temperature of thermolysis assisted the formation of such pores.

Cyclohexylammonium Hexaisothiocyanatonickelate(II) Dihydrate as a Single-Source Precursor for High Surface Area Nickel Oxide and Sulfide Nanocrystals

“…Synthesis of (C 6 H 11 NH 3 NCS): cyclohexylammonium thiocyanate (C 6 H 11 NH 3 NCS) was obtained from the metathesis reaction between cyclohexylammonium chloride and sodium thiocyanate in ethanol medium, as it was described in the literature [26,34,38]. The synthesis of C 6 H 11 NH 3 NCS was the second step in our approach.…”

“…The simulated X-ray diffraction pattern can be used as a reference standard when there is a good match between the simulated pattern of the structure and the experimental one. By comparing the experimental XRPD pattern (Figure 6C) with the simulated ones of Figure 6A or Figure 6B, one can observe that the number of peaks of the experimental pattern exceeded those of the simulated ones due to the disorder in the number of carbon and oxygen atoms, as illustrated in Table 5, which obviously broke the standard of two formula units per primitive cell [26,38]. The more atoms, existing inside the primitive cell, might create different families of Bragg reflection planes, and consequently, generate more X-ray diffraction peaks.…”

“…On the basis of the organic cation, cyclohexylammonium is a unique building block due to its capability to form various dimensional structures, depending on the identity of its counter anion and the presence of solvent of crystallization molecules, via its hydrogen donor nature . Another attractive feature of cyclohexylammonium is its usefulness as a soft organic template for the creation of mesopores, after its thermal decomposition, within the produced ceramic [26,38,39].…”

“…Although there have been thorough investigations of several thiocyanate or isothiocyanate metal compounds, none of them has been utilized as an SSP for metal sulfides or oxides [3,8,12,13,[47][48][49][50][51][52][53]. Recently, we have reported cyclohexylammonium tetraisothiocyanatocobaltate(II) as an SSP for cobalt sulfide (CoS) and tricobalt tetraoxide (Co 3 O 4 ) nanoparticles [26], while cyclohexylammonium hexaisothiocyanatochromate(III) sesquihydrate as an SSP for nanocrystalline chromium sulfide (Cr 2 S 3 ) and chromium oxide (Cr 2 O 3 ) [38].…”