Preparation of Magnetic CuFe2O4@Ag@ZIF-8 Nanocomposites with Highly Catalytic Activity Based on Cellulose Nanocrystals

Abstract

A facile approach was successfully developed for synthesis of cellulose nanocrystals (CNC)-supported magnetic CuFe 2 O 4 @Ag@ZIF-8 nanospheres which consist of a paramagnetic CuFe 2 O 4 @Ag core and porous ZIF-8 shell. The CuFe 2 O 4 nanoparticles (NPs) were first prepared in the presence of CNC and dispersant. Ag NPs were then deposited on the CuFe 2 O 4 /CNC composites via an in situ reduction directed by dopamine polymerization (PDA). The CuFe 2 O 4 /CNC@Ag@ZIF-8 nanocomposite was characterized by TEM, FTIR, XRD, N 2 adsorption-desorption isotherms, VSM, and XPS. Catalytic studies showed that the CuFe 2 O 4 /CNC@Ag@ZIF-8 catalyst had much higher catalytic activity than CuFe 2 O 4 @Ag catalyst with the rate constant of 0.64 min −1 . Because of the integration of ZIF-8 with CuFe 2 O 4 /CNC@Ag that combines the advantaged of each component, the nanocomposites were demonstrated to have an enhanced catalytic activity in heterogeneous catalysis. Therefore, these results demonstrate a new method for the fabrication of CNC-supported magnetic core-shell catalysts, which display great potential for application in biocatalysis and environmental chemistry.Molecules 2020, 25, 124 2 of 15 More often, hybrid composites are fabricated through an in-situ method, where the templates have a high affinity towards metal ions that allows for the synthesis of metallic nanoparticles [8]. Cellulose nanocrystals (CNC) are derived from abundant cellulosic resources such as plants and microbial cellulose via sulfuric acid hydrolysis [9,10]. CNC have well-defined size and morphology, high specific surface area, high aspect ratio, high crystalline order, chirality, high mechanical strength, and controllable surface chemistry [11], which are appealing in a plethora of materials to catalytic applications. As reported in our previous research [12], the CuFe 2 O 4 /CNC nanocomposites show good dispersity and it has been suggested that the nanocomposites do catalyze 4-NP reduction.To further improve the catalytic activity, various core/shell-structured magnetic nanocatalysts have been applied in nanocatalysis [13][14][15][16]. The as-obtained CuFe 2 O 4 based core-shell nanocomposites showed excellent catalytic activity, magnetic separation, and magnetic carrying in nanocatalysis. Recently, the Ag modified magnetic composites have gained increasing attention because of the high catalytic activity of the Ag component, the good magnetic responsiveness of the magnetic core, and the relatively facile fabrication process [17][18][19]. Various noble metals, including Au, Pd, and Pt have been widely employed as catalysts for the reduction of 4-NP to 4-AP by NaBH 4 in aqueous media [20][21][22][23]. Moreover, Ag is more suitable for large-scale application than other noble metals (Au, Pd, and Pt) because of its low price [24]. Dopamine can self-polymerize under specific conditions to form a polydopamine (PDA) complex which has the ability of adhering onto the surface of various materials due to the strong stickiness [25][26][27] and the abundant catech...

Statistically Analyzed Heavy Metal Removal Efficiency of Silica-Coated Cu0.50Mg0.50Fe2O4 Magnetic Adsorbent for Wastewater Treatment

“…The image of Figure (c) shows the high-resolution TEM images of the nanoparticle, clearly showing the patterns of lattice fringes in the nanoparticles. The prominent lattice fringes with 0.248 nm interplanar spacing correlate well with (311) crystal plane of the cubic spinel structure . TEM images showed the predictable orientation of lattice fringes by suggesting a better crystallinity of the structures.…”

Improving SERS Sensing Efficiency and Catalytic Reduction Activity in Multifunctional Ternary Ag-TiO2-GO Nanostructures: Roles of Electron Transfer Process on Performance Enhancement

“…A model of catalytic reduction was selected as its performance is directly related to electron transfer phenomena. The catalytic reduction model was studied through the reduction of 4-NP to 4-AP using NaBH 4 as an electronic providing source from BH 4 - to investigate the catalytic reduction properties of ATG Nces [34]. To clarify the role of TiO 2 and GO on the catalytic reduction performance of ATG Nces, we prepared two sets of samples.…”

“…The peak at 400 nm in UV-Vis spectra, which is ascribed to 4-nitrophenolate ions, would be decreased gradually with time in the presence of catalytic materials, signifying the degradation of 4-NP. Contemporaneously, the appearance of a new band at 300 nm represents the formation of 4-AP [34]. Figure 4 demonstrates the absorption spectra of the reaction samples using different catalytic materials in the two experimental sets.…”

Molecular Linking Selectivity on Self-Assembled Metal-Semiconductor Nano-Hybrid Systems

“…The 6e − catalytic reduction of 4-NP was used as a model reaction to test the photocatalytic performance of the systems since this is a trusted reaction to test nanoparticles reactivity [28] and plasmonic photocatalysis [29,30]. The mechanism of the reduction has been studied thoroughly elsewhere [31,32], in which the surface of transition metal is a favorable binding site of 4-NP. In the presence of NaBH 4 , the reduction follows the Langmuir-Hinshelwood mechanism, which involves the reaction of the active hydrogen (hydride) from NaBH 4 produced on the metal with the adsorbed 4-NP.…”