Facile Synthesis of CuMgFe Layered Double Hydroxides for Efficient Catalytic Phenol Hydroxylation under Mild Conditions

Abstract

A series of CuMgFe layered double hydroxides (denoted as X/CuMgFe–LDHs) with different Cu contents were synthesized by co‐precipitation as catalysts for phenol hydroxylation under mild conditions. The as‐prepared samples were analyzed by X‐ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP‐ES), N2 adsorption–desorption, Fourier transform infrared (FT‐IR), thermogravimetric differential scanning calorimetry (TG‐DSC), X‐ray photoelectron spectroscopy (XPS) and hydrogen temperature‐programmed reduction (H2‐TPR) to investigate the morphologies and physicochemical properties. As presented by the characterization results, introducing a certain amount of copper not only increased the amount of active metal centers but also formed more oxygen vacancies and lattice oxygen to promote electron transport between the double layers in LDHs. However, the excess copper would significantly disrupt the X/CuMgFe–LDH framework, declining the activity. Therefore, the 20/CuMgFe–LDH sample presented the best catalytic performance among all the catalysts in terms of activity, which was correlated with the layered structure, low‐temperature reducibility, oxygen species and low Cu+/Cu2+ and Fe2+/Fe3+ ratios. The catalyst could maintain good stability even after recycling for five times. Finally, a possible mechanism for phenol hydroxylation via Cu+–OV–Fe2+ and Cu2+–O–Fe3+ redox cycles on CuMgFe–LDHs was proposed.

A bimetallic synergistic effect on the atomic scale of defect-enriched NiV-layered double hydroxide nanosheets for electrochemical phenol hydroxylation

“…The huge specific surface area and hydrophilic characteristic of NiV-LDH-NS allowed the reactants to be more vulnerable to access into the active center. 47–49 Because the Ni( ii )-containing species were difficult to oxidize to a higher valent state but much easier for the conversion of V, the higher valent state of V was preferentially generated. 31 Electrochemical results indicated that the activity of phenol hydroxylation was dominated by the higher valent states of V (V 4+ /V 5+ ), which could be further affected by the synergistic behavior of Ni in NiV-LDH-NS.…”

Ternary layered double hydroxide cathode materials for electrochemical energy storage: a review and perspective

“…11e). 50 In 2020, Li et al synthesized a binderless NiMnCr-LDHs@CS/NF composed of NiMnCr-LDHs coated on carbon balls (CS) coated on foamed nickel by a two-step hydrothermal method, and applied it to the anode of SCs. In addition, a hybrid SC was fabricated by using NiMnCr-LDHs@CS/NF as the positive electrode and FeOOH nanorods (FeOOH/NF) deposited on NF as the negative electrode.…”

“…LDHs have been shown to be extraordinary catalyst supports in different heterogeneous reactions, including the oxidation of organics, the synthesis of 2-ethyl-1-hexanol, and the hydroxylation of phenol. 50 In terms of electrochemistry, electrodes still suffer from low capacitance and inferior rate performance at high current densities. LDHs have been introduced into carbon materials with the aim of obtaining enhanced energy density and life cycles of SCs.…”

“…(e) Cycling properties of the assembled capacitor. The inset shows the CV curves for the 1st and 5000th cycles measured at 50 mV s À1 50. Copyright 2022, Elsevier.…”

A Type of MOF-Derived Porous Carbon with Low Cost as an Efficient Catalyst for Phenol Hydroxylation

“…It can also be used to produce dyes, photosensitive materials, electroplating materials, special inks, auxiliaries, and so on. Hydroquinone was mainly used in developer, anthraquinone dyes, azo dyes, synthetic ammonia cosolvents, rubber antioxidants, polymerization inhibitors, stabilizers for coatings and flavors, and antioxidants [1][2][3][4][5].…”