Hybrid Metal–Organic-Framework/Inorganic Nanocatalyst toward Highly Efficient Discoloration of Organic Dyes in Aqueous Medium

Abstract

Nanoscale metal–organic frameworks (NMOFs) represent a unique class of solids with superior adsorption, mass transport, and catalytic properties. In this study, a facile and novel approach was developed for the generation of hybrid Cu-NMOF/Ce-doped-Mg-Al-LDH nanocatalyst through in situ self-assembly and solvothermal synthesis of a 2D Cu-NMOF, [Cu2(μ-OH)­(μ4-btc)­(phen)2] n ·5nH2O {H3btc, trimesic acid; phen, 1,10-phenanthroline}, on a cerium-doped Mg-Al layered double hydroxide (Ce-doped-Mg-Al-LDH) matrix. Self-assembly between Cu-NMOF nanocrystals and exfoliated LDH led to their nanoscale mixing and prevented the formation of aggregated Cu-NMOF nanoparticles. In the resulting hybrid nanostructure, Cu-NMOF nanocrystals (∼10–20 nm particle size) are anchored uniformly on a Ce-doped-Mg-Al-LDH’s surface, possessing a dimension of several hundred nanometers. Catalytic activity of Cu-NMOF/Ce-doped-Mg-Al-LDH and Cu-NMOF was evaluated under ambient conditions in the reductive degradation (discoloration) of aqueous solutions of 4-nitrophenol (4-NP, model substrate) and a series of commercial organic dyes by applying sodium borohydride as a reducing agent. The Cu-NMOF/Ce-doped-Mg-Al-LDH nanocatalyst exhibited an outstanding catalytic activity toward degradation of 4-NP, with k app (rate constant) of 0.03 and a catalyst TOF (turnover frequency) up to 7.1 × 103 h–1. Full and very quick discoloration of organic dyes {rhodamine B (RhB), methylene blue (MB), Congo red (CR), methyl orange (MO), and rhodamine 6G (R6G)} was also achieved with TOF values of up to 1.4 × 105/h. A superior activity of the hybrid nanocatalyst over Cu-NMOF can be regarded as a synergic effect among Cu-NMOF and Ce-doped-Mg-Al-LDH components, while the Ce-doped-Mg-Al-LDH carrier acts as a cocatalyst. The hybrid nanocatalyst can easily be recovered and reused successfully for the five consecutive reaction runs with the same catalytic performance. This study also shows that NMOFs can be easily incorporated onto conventional catalyst supports, resulting in hybrid nanocatalysts with a highly uniform structural architecture, controlled chemical composition, and excellent catalytic function.

Preparation of Magnetically Recoverable MPCTP-Ag Composite Nanoparticles and Their Application as High-Performance Catalysts

“…The rate constants of 4-NP, MB, and MO are 0.6035, 0.7589, and 0.5787 min –1 , respectively, which are higher than those reported in studies ( k 4‑NP = 0.518 min –1 , k MB = 0.270 min –1 , and k MO = 0.254 min –1 ). , In order to evaluate the catalytic efficiency of the catalyst more accurately, we calculated its turnover frequency (TOF). The TOF is obtained from calculation by dividing the concentration of the reactant material (4-NP, MO, and MB) with the amount of decorated metal particles and the reaction time . The Ag content of the catalyst determined by ICP-AES was about 5.11 wt %, and the specific data are provided in Table S2.…”

“…The TOF is obtained from calculation by dividing the concentration of the reactant material (4-NP, MO, and MB) with the amount of decorated metal particles and the reaction time. 37 The Ag content of the catalyst determined by ICP-AES was about 5.11 wt %, and the specific data are provided in Table S2. The TOF values were calculated to be 155.93, 727.66, and 172.34 h −1 for the reduction of 4-NP, MO, and MB, respectively.…”

Hollow N‐ZIFs@NiCo‐LDH as highly efficient catalysts for 4‐nitrophenol and dyes

“…The absorption of this peak remains constant within 5 h which indicates that the reduction does not proceed in the absence of catalyst (Figure 7b). [34] However, after N-ZIFs@NiCo-LDH were added, the peak at 400 nm decreased rapidly and an increase in the peak at 300 nm was seen due to the formation of 4-AP, along with the yellow color fading, suggesting the reduction of 4-NP had occurred. [35] The results for the catalytic reaction are displayed in Figure S4.…”

Recent Revolutions in Nanoscience and Nanotechnology with Its Application’s

“…The use of cancer specific targeting residues (e.g. antibodies, ligands, and lectins) can also achieve tumor cell targeting [34][35][36][37][38][39][40][41][42][43].…”