Abstract
Spherical materials with yolk‐shell structure have great potential for a wide range of applications. The main advantage of the yolk‐shell geometry is the possibility of introducing different chemical or physical properties within a single particle. Here, a one‐step hydrothermal synthesis route for fabricating amphoteric yolk‐shell structured aluminum phenylphosphonate microspheres using urea as the precipitant is proposed. The resulting microspheres display 3D sphere‐in‐sphere architecture with anionic core and cationic shell. The controllable synthesis of aluminum phosphates with various morphologies is also demonstrated. The anionic core and cationic shell of the aluminum phenylphosphonate microspheres provide docking sites for selective adsorption of both cationic methylene blue and anionic binuclear cobalt phthalocyanine ammonium sulphonate. These new adsorbents can be used for simultaneous capture of both cations and anions from a solution, which make them very attractive for various applications such as environmental remediation of contaminated water.
Highlights
Introduction shellsBy adapting an organosilane-assisted etching method, Yang et al demonstrated the fabrication of yolk-shell nanoparticles (YSNs) with a basicPorous microspheres are of great interest for a variety of core and an acidic shell.[5]
The high-resolution scanning electron microscopy (SEM) (HRSEM) images (Figure 1b,c) further reveal that the surface of ys-AlPhPO is relatively smooth, the 500 nm thick porous shells are disorderly self-assembled by a large number of rod-like nanoparticles with a size of 50 × 200 nm, and the size of hollow space between core and shell is around 200 nm
The energy dispersive X-ray (EDX) mapping analysis (Figure 1d–f) indicates aluminum and phosphorus homogeneously distributed throughout the whole microsphere
Summary
The synthesis involves a facile template-free hydrothermal process using urea as a precipitant, in the presence of phenylphosphinic acid (PPA, C6H7O3P) and aluminum nitrate to form yolk-shell structured aluminum phenylphosphonate microspheres. As can be seen in the panel (a) of this figure the sample is composed of uniform and well-dispersed yolk-shell structured microspheres with an average diameter of about 7 μm. The energy dispersive X-ray (EDX) mapping analysis (Figure 1d–f) indicates aluminum and phosphorus homogeneously distributed throughout the whole microsphere. The morphology of yolk-shell structured microspheres is confirmed by the transmission electron microscopy (TEM) image (Figure 2). The porous structure of ys-AlPhPO microspheres is further evidenced by N2 sorption analysis (Figure S1, Supporting Information). The solid-state NMR together with the FT-IR data (Figure S4, Supporting Information) demonstrate the incorporation of phenylphosphonate into the framework through the coordination between aluminum and phenylphosphonate, and confirm that the phenylphosphonate can retain the structural integrity during the hydrothermal synthesis process
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