Structural Studies of Multifunctional SrTiO₃ Nanocatalyst Synthesized by Microwave and Oxalate Methods: Its Catalytic Application for Condensation, Hydrogenation, and Amination Reactions

Abstract

The present study deals with the synthesis of SrTiO 3 (STO) nanocatalysts by conventional oxalate and microwave-assisted hydrothermal methods. Thorough characterization of the nanocatalysts synthesized has been done by using various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, N 2 physisorption, transmission electron microscopy, total acidity by pyridine adsorption method, and acidic strength by n -butylamine potentiometric titration, respectively. Structural parameters were estimated by Rietveld refinement analysis from XRD data which confirms cubic structure of SrTiO 3 . Traces of impurities such as TiO 2 and SrCO 3 were found in conventional catalysts, whereas these are absent in microwave catalyst. Brunauer–Emmett–Teller (BET) surface area of the microwave catalyst was enhanced 14-folds compared to conventional catalyst. Increase in Lewis acid sites and their strength were also observed in STO microwave catalyst. Catalytic performance of the catalysts was evaluated for various reactions, such as Knoevenagel condensation of benzaldehyde, catalytic transfer hydrogenation of nitrobenzene, and amination of benzaldehyde. Catalytic results reveal that microwave-synthesized catalyst showed 100% conversion and selectivity (>99% yield) for the chosen reactions than the conventional catalyst. Excellent catalytic activity of the STO microwave catalyst was due to high BET surface area, pore volume, and acidity of the catalyst, as compared to conventional catalyst. The present study marks the first-time application of perovskite-based SrTiO 3 as a potential multitasking cost-effective catalyst for the above reactions and synthesized using environment friendly microwave synthesis method.

Synthesis of ZnTiO3@TiO2 Heterostructure Nanomaterial as a Visible light Photocatalyst

“…The corresponding SAED (selected area electron diffraction) pattern (see Figure (b)) shows the nanoparticles are well crystalline and the calculated (012), (004), and (211) plane corresponds to ZnTiO 3 , anatase TiO 2 , and rutile TiO 2 . Figure (c) shows the EDX (Energy dispersive X‐ray) spectra of the ZnTiO 3 @TiO 2 heterostructure nanomaterial, indicating the presence of Zn, Ti, and O only in the ZnTiO 3 @TiO 2 heterostructure nanomaterial …”

Superparamagnetic and photocatalytic activity of CoCe0.02Dy0.02Fe1.96O4 nanoparticles synthesized by citrate-gel autocombustion technique

“…During the experiments, we observed that the colour of MB changed to light blue and eventually to a clear solution with degradation process. The decolourization of MB is not an indication of mineralization as it may be converted to a colourless substances [12,13]. The change in concentration of MB as a function of time in the presence of asprepared samples is shown in Fig.…”

Analyzing the surface of functional nanomaterials—how to quantify the total and derivatizable number of functional groups and ligands

“…Potentiometric titrations have been used for characterizing the surface chemistry of different types of organic and inorganic NM with various FG, and have been applied to determine the number and nature of acidic sites (carboxy, lactone, phenol, and ester groups) on carbonbased materials like carbon dots (CD), nanocellulose/ nanobentonite composites, biochar particles, multi-walled carbon nanotubes, or cellulose nanocrystals [76][77][78][79][80], or to quantify hydroxy (silanol) and thiol groups on hybrid silica particles [81]. Potentiometric titrations have also been used to determine the total number of acidic sites on different catalyst materials like phosphotungstic acid-functionalized Sn-TiO 2 and organic-inorganic polyoxometalate NP, SrTiO 3 particles used to catalyze condensation, hydrogenation, and amination reactions, functionalized silica particles employed as catalysts for the esterification of linoleic acid, and photocatalytic TiO 2 / S-doped carbon hybrids [82][83][84][85][86]. For example, Wang et al potentiometrically quantified carboxy and amino groups on fluorescent CD prepared with different amounts of L-arginine or L-glycine (see Fig.…”