New Applications of Zirconium Phosphate Nanomaterials

Abstract

Conspectus The 2-D layers of the inorganic ion exchanger α-zirconium phosphate (Zr­(HPO4)2·H2O, α-ZrP) make this compound particularly stable to low pH, high temperature, and ionizing radiation. Initially studied for its ion exchange properties, once the conditions for its synthesis in crystalline form was accomplished by James Stynes and Abraham Clearfield in 1964, numerous other types of studies and applications followed. Extensive studies in the 1960s and 1970s on the thermodynamics of ion exchange led to insights into the intercalation mechanism of this material. The Clearfield group solved the crystal structure in 1968 and refined it in 1977. Powder methods were pioneered by the Clearfield group to solve the structure of this type of materials. In 1968 Giulio Alberti reported means to prepare zirconium phosphonates expanding the chemistry of these layered compounds. New phases of ZrP were also discovered (e.g., γ, θ, λ, τ) and the applications ranged from heterogeneous catalysis to intercalation chemistry and solid-state proton conductors. Methods to exfoliate the layers of ZrP were developed in the 1990s as interest grew in new applications of these types of materials. For example, protein and enzyme intercalation was accomplished starting in the 1990s by the McLendon, Mallouk, and Kumar groups. In the early 2000s, the Colón group pioneered the use of the θ phase of ZrP for the direct intercalation of large inorganic metal complexes that could not be directly intercalated into the α phase. Initial studies in the Colón group ranged from applications of these directly intercalated ZrP derivatives in photophysics and photochemistry, amperometric biosensors, vapochromism, and vapoluminescence. Over the past decade, new applications of these materials have been developed in anticancer drug delivery and electrocatalysis of the oxygen evolution reaction (OER). ZrP has now proven to be a promising drug nanocarrier and its unique chemical microenvironment provided by the α-type layers and the interlayer space enhances catalytic activity for numerous types of reactions. Further elucidation of the catalytic active species under operando conditions as well as the chemical structure of drug-intercalated derivatives should provide new insights that will advance the design and development of new compounds with desired properties. The initial pioneering efforts of Clearfield and Alberti are being continued by numerous research groups providing new exciting areas of development on the chemistry of layered M­(IV) phosphate and phosphonate compounds. In this Account we present the efforts of the Colón group during the past decade on studies of the applications of ZrP for anticancer drug delivery and electrocatalysis of the OER.

Multilayered Architecture Assembled from Sn(HPO4)2 Nanosheets and Reduced Graphene Oxide As Superior Cyclability Anodes for Sodium-Ion Batteries

“…Figure a,b demonstrates the uniform two-dimensional lamellar morphology of SNSs with a width of ∼1 μm. The AFM image (Figures c and S1) shows that the inner thickness of the partial nanosheet of SNS is about 2.25 nm and the edge thickness is about 3.3 nm, which is attributed to the intercalation of TBA + in the crystals by the diffusion of ions from the outer surface inward with an advancing phase boundary, , leading to a tendency for greater edge thickness. Remarkably, due to the same charge of SNS and GO in aqueous solution, the homogeneous GO/SNS dispersion obtained by adding GO into the above-mentioned SNS aqueous dispersion delivers a zeta potential of up to −34.2 mV under the electrostatic repulsion of both (Table S2).…”

High strontium adsorption performance of layered zirconium phosphate intercalated with a crown ether

“…18,19 a-ZrP (Zr(HPO 4 ) 2 $H 2 O) is a two-dimensional layered phosphate with a layer spacing of 0.76 nm and a large number of P-OH groups between the layers. 20,21 The hydrogen protons in P-OH groups can be exchanged with other metal ions, [22][23][24] demonstrating their good ion-exchange properties. Furthermore, the zirconium phosphate material has a good adsorption capacity for alkali metals and alkaline earth metals, as well as for Sr-90 in radioactive waste streams.…”

“…22,25 As the weak interlayer force makes the a-ZrP layer spacing adjustable, the guest molecules can be inserted under certain conditions to change the properties of the host or the guest. 23,27,28 The pre-intercalation method is generally used to prepare composite of host and guest materials, and the preintercalation materials used to adjust interlayer space of the zirconium phosphate are mainly amine molecules. 28 Aer insertion of an amine molecule, the carbon skeleton of the amine molecule and the layer of the zirconium phosphate are maintained as a single parallel structure or a double-layer oblique insertion structure, which plays a vital role in expanding the interlayer space.…”

Assembly of exfoliated α‐zirconium phosphate nanosheets: Mechanisms and versatile applications

“…Since the first report of crystalline α-ZrP in 1964, [1] thanks to its simple synthesis, rich surface chemistry, ease of intercalation and exfoliation, and unique physicochemical properties, α-ZrP has found widespread application in many fields including mechanical reinforcing, barrier improvement, flame retardancy, anticorrosion, catalysis, environment, energy, and medicine. [29][30][31] Figure 2A presents the number of papers published on α-ZrP every half a decade since 1964, which clearly shows that the number of papers has been soaring, covering many disciplines (Figure 2B). Intercalation and exfoliation have been two key processes to investigate the properties and explore the applications of α-ZrP.…”