Decorated multi-walled carbon nanotubes with Sm doped fluorapatites: synthesis, characterization and catalytic activity

Abstract

Novel and sustainable heterogeneous catalysts, namely, multi-walled carbon nanotubes (MWCNT) decorated with Sm doped fluorapatite nanocomposites (MWCNT/Sm-FAp) were prepared by facile co-precipitation method using glutamic acid as an organic modifier with different loadings of Sm (1%, 2%, 3%, 5%, and 7%). The nanocomposites were characterized by powder X-ray diffraction (PXRD), Fourier transform infra-red spectroscopy (FT-IR), microscopic techniques (FESEM, HRTEM), energy dispersive X-ray spectrometer (EDX) and Brunauer–Emmett–Teller method (BET) surface area, and thermogravimetric analysis (TGA). The SEM and TEM results confirmed that with varying Sm loading, the nanocomposites attained varied particles sizes in the nano-grade scale with different morphologies. The N₂ adsorption isotherm results showed that the BET surface area of nanocomposites enhanced from MWCNT/1% Sm-FAp (47.60 m² g⁻¹) to MWCNT/7% Sm-FAp (62.00 m² g⁻¹). The robust catalytic behavior of the MWCNT/Sm-FAp nanocomposites impressively showcased the esthetic results in the highly selective synthesis of the 1,2,4-triazole moiety from aromatic aldehydes. The catalytic efficiency increased with rise in Sm% from 1% to 5% in the nanocomposite. With MWCNTs/5% Sm-FAp nanocomposite as the catalyst, the reaction recorded 96% yield of triazole in short reaction times (10 min).