A kinetic and mechanistic study into the formation of the Cu–Cr layered double hydroxide

Abstract

The formation of the layered double hydroxide [Cu 2 Cr(OH) 6 ]ClÁyH 2 O from the reaction between CuO and aqueous CrCl 3 Á6H 2 O was explored using synchrotron X-ray diffraction and ex situ analyses. The use of hard X-rays permitted time-resolved in situ studies to be performed as the reaction proceeded under a range of conditions. Additional information was obtained from ex situ experiments in which aliquots of the reaction mixture were removed, quenched, and subsequently analysed by laboratory X-ray diffraction, IR, UV-visible, and atomic emission spectroscopies. On the basis of these data, it is proposed that the reaction involves three steps. First, the solid CuO starting material is hydrolysed to give Cu(OH) 2 chains, releasing Cu 2+ ions into solution. The Cu hydroxide chains subsequently condense with aqueous Cr 3+ species, Cl À ions and water molecules to give a hydrated form of the LDH. This material then extrudes some water to form a phase with a reduced interlayer spacing.

Layered Double Oxides for Sensing Reducing Volatile Organic Compounds: The Effect of Local Charge Region Modulation

“…Figure 2 showed the representative FESEM images of CuCr‐, ZnCr‐ and ZnTi‐LDOs samples and their corresponding LDHs precursors. Note that the synthesis of 2D CuCr‐LDHs in Figure 2(a) was rarely explored before, for Cu atoms are generally enforced to lie in the energetically unfavorable position in the brucite‐type structure due to Jahn‐Teller effect [22–25] . In present work, the 2D CuCr‐LDHs were synthesized successfully by a soft template (SDS) assisted hydrothermal precipitation method, as shown in Figure 2(a).…”

“…Note that the synthesis of 2D CuCr-LDHs in Figure 2(a) was rarely explored before, for Cu atoms are generally enforced to lie in the energetically unfavorable position in the brucite-type structure due to Jahn-Teller effect. [22][23][24][25] In present work, the 2D CuCr-LDHs were synthesized successfully by a soft template (SDS) assisted hydrothermal precipitation method, as shown in Figure 2(a). Observe that the obtained CuCr-LDHs show morphology of well-defined 2D nanosheets with thickness of about 30-50 nm.…”

In Situ Growth and Interlayer Modulation of Layered Double Hydroxide Thin Films from a Transparent Conducting Oxide Precursor

“…Therefore, in situ synthetic methods that can grow uniform LDH thin films are required for more widespread utilization of LDH materials. In situ methods using metal foil or foam as either reactants or substrates have been demonstrated to synthesize [Zn 2+ -Cr 3+ ], [Zn 2+ -Al 3+ ], [Cu 2+ -Al 3+ ], [Mg 2+ -Al 3+ ], [Ni 2+ -Co 3+ ], and Fe 3+ -based LDHs thin films. − Others have investigated the use of metal oxides as LDH reactants and growth substrates . ZnO powder was first demonstrated as a reactant to synthesize bulk [Zn 2+ -Cr 3+ ] LDH powder in 1977; however, the reaction required several days .…”

Size-dependent effect of MgAl-layered double hydroxides derived from Mg(OH)2 on thermal stability of poly(vinyl chloride)

“…More recently, the so-called "green" synthesis route has been developed using mixture between metal oxide and hydroxide or salt-oxide and hydroxide to reduce drastically the amount of water used during the washing step [26][27][28][29][30]. However, the former is difficult to yield LDH platelets suitable as thermal stabilizer for transparent PVC due to their sizes too large beyond micrometer [31], while the latter is not reported to fabricate LDH filler as PVC stabilizer so far [20].…”