Abstract
Transition metals' exceptional ability and properties at the nanoscale level transcend their corresponding bulk metals in chemical transformation both in the laboratories and the industries. However, the nanoparticles are prone to particle growth and agglomeration at this nanoscale state, inhibiting their excellent performance and compromising their uniqueness. Hence, the stability of the particles presents a significant factor in governing their innovative attributes. Therefore, organic polymers, such as polyvinylpyrrolidone (PVP) and dendrimer, were considerably employed as soft templates to ensure stability and prevent the agglomeration of these nanoparticles in a homogeneous phase. These synthesized nanoparticles include AuPVP, PdPVP, AuPdPVP nanoparticles, and CuDENs. Although conventional homogeneous catalysts possess a vast tendency to enhance high conversion and product selectivity in chemical reactions, nevertheless, they present limiting phenomenon of recoverability, recyclability, and deactivation at high temperatures. Therefore, to circumvent these limitations, we fabricated metal nanoparticles through the dispersion of metals onto an insoluble and solid mesoporous silica and metal oxide support by adapting a dual templating approach, followed by a galvanic replacement protocol. In addition, inverse micelle, sol-gel, and wet impregnation methods were also employed to design ideal heterogeneous catalysts such as Cun@SiO2, Au@SiO2, Pd@SiO2, CoMMO, and MnMMO, which are capable of high operating procedures, easy recoverability, and reusability for oxidation and reduction reactions. Different analytical techniques were used to characterize and obtain the properties of these catalysts. These techniques include nitrogen sorption with Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) to examine the surface area, pore size, and pore volume distribution, high-resolution transmission electron microscopy (H-TEM) for internal morphologies, powder X-ray diffraction (p-XRD), for the diffraction patterns of the materials. While thermogravimetric analysis (TG) was performed to determine the sample’s thermal stability, Fourier transform infrared spectroscopy (FT-IR) identified the specific functional groups present. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) obtained the surface morphologies and identification of metal composition. In addition, hydrogen-temperature programmed reduction (H2-TPR) was used to examine the reducibility of the catalyst...
Ph.D. (Chemistry)