Development of heterogeneous catalysts from biomass-derived activated carbon is a challenging task. Biomass-derived activated carbon possesses a large specific surface area, highly porous structure, and good thermal/chemical stability. Magnetic copper catalysts based on biomass-derived activated carbon exhibited good catalytic activity in base-free Chan–Lam coupling and oxidations. Herein, biomass-derived activated carbon was prepared by the carbonization of neem dead leaves (abundant waste biomass) followed by chemical activation with KOH. Such a porous carbon material was used as a low cost and highly efficient support material for the preparation of inexpensive and environmentally benign magnetic catalysts [Cu@KF-C/MFe2O4, M = Co, Cu, Ni, and Zn]. In addition, KF modification was done to impart basic character to the catalyst that can perform C–N coupling under base-free conditions. Initially, Brunauer–Emmett–Teller (BET) analysis of the synthesized catalysts was carried out, which indicated that Cu@KF-C/CoFe2O4 possess more surface area as well as pore volume, and so accounting for the highest activity among the other synthesized catalysts. Further, X-ray photoelectron spectroscopy (XPS) analysis was performed, which inferred that Cu@KF-C/CoFe2O4 contains most of the copper in reduced form, i.e., Cu(0), which is the active species responsible for better catalytic activity toward Chan–Lam coupling reactions as well as oxidation of alcohols and hydrocarbons. The physiochemical properties of the most active catalyst, Cu@KF-C/CoFe2O4, was examined by BET, XPS, Fourier transform infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission gun scanning electron microscopy (FEG-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX) mapping, energy dispersive X-ray (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), powder X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Moreover, Cu@KF-C/CoFe2O4 shows excellent stability as well as reusability and could be easily separated with the help of an external magnet.

Cu@Ag–TiO2–NGO prepared from modified graphene by simple methodology exhibits enhanced catalytic activity towards oxidation and Chan–Lam coupling due to the synergistic effect between Ag and Cu NPs.

Chromium(III)‐doped layered double hydroxide supported copper nanoparticles (Cr3+‐Cu0/LDH) has been prepared as an efficient and reusable catalyst using simple and versatile synthetic method. Effect of doping of Cr3+ to the layered double hydroxide supported Cu0 nanoparticles was evaluated for the oxidation of alcohols and hydrocarbons by varying the amount of Cr3+ loading in the catalyst. The catalyst with Cu:Cr ratio= 1:1 afforded highest catalytic activity among the synthesized catalysts towards the oxidation using TBHP (tBuOOH) in aqueous medium and was structurally characterized by Fourier Transform Infrared Spectroscopy (FTIR), X‐Ray Diffraction Spectroscopy (XRD), Field Emission Gun‐Scanning Electron Microscopy (FEG‐SEM), Energy‐dispersive X‐Ray Spectroscopy (EDX), High Resolution‐Transmission Electron Spectroscopy (HR‐TEM), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP‐AES) and X‐Ray Photoelectron Spectroscopy (XPS). The high activity and selectivity was assigned to the synergistic electronic interaction between copper(0) nanoparticles and chromium(III) ions based on experimental data and XPS results. Moreover, the high stability of Cu0 and Cr3+ in the catalyst was attributed to the strong metal‐support interactions, which make the catalyst recyclable upto five runs.

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Tuning the catalytic activity and selectivity of a heterogeneous transition nano-metal catalyst by the controlled incorporation of a foreign entity (dopant) into its structure is of paramount importance although a...