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

Novel and sustainable heterogeneous catalysts, namely, multi-walled carbon nanotubes (MWCNT) decorated with Sm doped fluorapatite nanocomposites (MWCNT/Sm-FAp) were prepared by facile coprecipitation 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 Xray 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 N-2 adsorption isotherm results showed that the BET surface area of nanocomposites enhanced from MWCNT/ 1% Sm-FAp (47.60 m(2) g(-1)) to MWCNT/7% Sm-FAp (62.00 m(2) 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).