Synthesis of Silica@Ni‐Co Mixed Metal Oxide Core–Shell Nanorattles and Their Potential Use as Effective Adsorbents for Waste Water Treatment

Abstract

SiO2@Ni‐Co mixed metal oxide core–shell nanorattles with different Ni2+/Co2+ molar ratios have been successfully synthesized through a facile, inexpensive self‐template route by the calcination of SiO2@Ni‐Co layered double hydroxides at 500 °C. The formation of SiO2@Ni‐Co mixed metal oxide core–shell nanorattles has been confirmed by an array of characterization techniques. Field‐emission scanning electron microscopy (FE‐SEM) analysis indicates a hierarchical flowerlike morphology for the SiO2@Ni‐Co mixed metal oxide core–shell nanorattles, and transmission electron microscopy (TEM) analysis confirms the formation of core–shell nanorattles. The diffuse reflectance spectra of the SiO2@Ni‐Co mixed metal oxide core–shell nanorattles show two band‐gap absorptions attributed to metal‐to‐ligand charge‐transfer transitions (Mn+→O2–). The SiO2@Ni‐Co mixed metal oxide core–shell nanorattles have been explored as effective adsorbents for the removal of rhodamine B, methylene blue, and their mixture from aqueous solutions. The adsorption of the single dye systems follows Langmuir and Freundlich isotherms, whereas a binary Langmuir model has been applied for the binary dye systems. The SiO2@Ni‐Co mixed metal oxide core–shell nanorattles possess higher adsorption capacity for the individual dyes than for the mixture of dyes. Kinetic studies indicate that the adsorptions of rhodamine B, methylene blue, and their mixture follow pseudo‐second‐order kinetics.

Fabrication of a 3D Hierarchical Sandwich Co9S8/α‐MnS@N–C@MoS2 Nanowire Architectures as Advanced Electrode Material for High Performance Hybrid Supercapacitors

“…Urea decomposes to produce NH 3 and CO 2 in the aqueous solution. After achieving the optimum temperature (e.g., 120 °C) under high pressure during hydrothermal reaction, NH 3 undergoes hydrolysis, and slowly releases OH − ions into aqueous solution that contains Mn 2+ and Co 2+ ions, which leads to the formation of MnCo layered double hydroxides (LDHs) . Here, ammonium fluoride acts as a structure directing agent, and it can promote the formation of 1D MnCo LDH nanowires.…”

“…In the first step, the weight loss (≈2.1%) from room temperature to 210 °C is attributed to desorption of the physisorbed water molecules. The major weight loss (≈22.7%) between 210 and 410 °C is attributed to the loss of interlamellar water molecules, and anions accompanied by the decomposition of the MnCo LDH, to form spinel MnCo 2 O 4 . The minimal weight loss (≈1.3%) between 410 and 900 °C is due to the decomposition of spinel MnCo 2 O 4 .…”

Facile Synthesis of Porous Flower‐Like Co3O4‐SiO2 Composite for Catalytic Decoloration of Rhodamine B

“…However, the atomic ratio of Si to Co increases from 0.49 to 1.28, attribute to the grown of silica onto Co(OH) 2 , which can also be proved by the thickening of the plates (as marked in Figure b‐d). In addition, the morphology of the sample in Figure d is similar to that in Figure a, implying the flower‐like structure is stable during the annealing process …”

A Facile and Effective Method for Constructing Rambutan‐Like NiCo2O4 Hierarchical Architectures for Supercapacitor Applications

“…The powder XRD (PXRD) pattern of the precursor (NiCo‐pre; Figure a) clearly shows typical features of nickel/cobalt double hydroxides . The overall crystallinity and phase purity of the NiCo 2 O 4 samples were also examined; the results are illustrated in Figure a.…”