Exploring the intercalation chemistry of layered yttrium hydroxides by 13C solid-state NMR spectroscopy

Layered rare earth hydroxides(LREHs)are a novel class of two-dimensional materials with potential applications in various fields.The exchange reactions with organic anions are typically the first step for the functionalization of LREHs.Although the laminar structures seem to be clear for anion-exchanged compounds,the state of intercalated organic anions and their interactions with cationic rare earth hydroxide layers remain unclear.Herein,we demonstrate that the use of 13C solid-state nuclear magnetic resonance(ssNMR)spectroscopy enables to extract key information on the state of intercalated organic anions such as their local chemical environment,stacking,and dynamics,which are often difficult or impossible to obtain previously.In combination with powder X-ray diffraction and ab initio density functional theory calculations,the intercalation chemistry of two representative layered yttrium hydroxides with selected monovalent organic anions was studied in detail.The products can undergo secondary exchange with a divalent organic anion,depending on the match between the basal spacing of two phases,i.e.,the replacement of benzenesulfonate(BS^(-)
),2,4-dimethylbenzene sulfonate(DMBS^(-)
),and 4-ethylbenzene sulfonate(EBS
)with 2,6-naphthalene disulfonate(NDS^(2-)
)is allowed due to the insignificant change in basal spacing after exchange,while the replacement of very long dodecyl benzene sulfonate(DBS^(-)
)and dodecyl sulfate(DS
)with NDS^(2-)is forbidden.The results therefore provide valuable insights into the structure-property relationships of LREH-based functional materials.

Synthesis and characterization of branched yttrium hydroxide fluoride microcrystals with hierarchical tubular structure

Hexagonal yttrium hydroxide fluoride microcrystals were prepared by a two-step hydrothermal routte using yttrium nitrate, sodium hydroxide and sodium fluoride as raw materials to react in propanetriol solvent. The samples were characterized by powder X-ray diffraction （XRD）, energy dispersive spectrum （EDS）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Fourier trans- form infrared spectroscopy （FT-1R）, thermogravimetre and differential-thermogravimetric analysis （TG-DTA）, which revealed that Y（OH）2.14F0.86 microerystals were multi-branched and that the branches of Y（OH）2A4F0.86 microcrystals were composed of hierarchical tubes. This novel multi-branched and intriguing hierarchical tubular structure of yttrium hydroxide fluoride maybe has a potential application in photoelectric crystals. The formation of branched Y（OH）2.14F0.86 microcrystals with hierarchical tubular structure were due to the substitution reaction and Oswald ripening.

Uptake and Speciation of Inorganic Arsenic with Cellulose Fibre Coated with Yttrium Hydroxide Layer as a Novel Green Sorbent

A novel adsorbent was developed by coating yttrium hydroxide precipitate layer on cellulose fibre. This material takes up ca. 98% of 5 μg·L 1 As（Ⅲ） and As（V） at low pH （pH〈7）, while a favorable selectivity for As（V） was achieved within pH 11--12. In practice, a mini-column packed with Y（OH）3 precipitate layer coated cellulose fibre particles was incorporated into a sequential injection system for selective uptake of arsenate at pH 11.5. The retained arsenate was afterwards recovered with 50μL of 0.8 mol.L l NaOH solution as eluent, followed by hydride generation in a reaction medium of 2.0 mol·L-1 HCl and 1.0% NaBH4 solution （W/V, in 0.5% NaOH） after pre-reduction of arsenate to arsenite by KI-ascorbic acid （5%, W/V）, with detection by atomic fluorescence spec- trometry. Total inorganic arsenic was quantitatively taken up at pH 6.0 by following the same procedure and arsenic speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 16.4 was derived with a detection limit of 17 ng.L-1 within a linear range of 0.05--2.0μg.L ]. A relative standard deviation （RSD） of 2.6% （0.5 μg·L-1, n= 11） was achieved. The procedure was validated by analyzing arsenic in a certified refer- ence material GBW 09101 （human hair）, and speciation process requires no organic solvents, thus Y（OH）3 coated of inorganic arsenic in natural water samples. The entire cellulose fibre provides a green adsorbent.