Polyoxometalate functionalized matrix material: synthesis, characterization, reductive and thermal degradation kinetics

Abstract

One-pot synthesis of polyoxometalate (POM) based hybrid material 1 was synthesized by mixing copper nitrate, silicomolybdic acid and urea under hydrothermal condition. The reduction ability of 1 was examined by employing 2,4,6-trinitrophenol (2,4,6-TNP) and 4-nitrophenol (4-NP) in the presence of sodium borohydride in water. The catalytic reduction into the corresponding amine was monitored by UV-Visible spectroscopy. The rate and order of catalytic reduction were studied through chemical kinetics and follows pseudo-first-order. The efficiency of the catalyst was investigated by employing used catalyst 1 for at least ten cycles. Leaching experiments and performance of the reusability of catalyst were supported by FT-IR analyses. In addition, the electrochemical reduction ability of catalyst 1 was also executed by Cyclic Voltammetry (CV). Catalyst 1 was characterized by Fourier-Transform Infrared spectroscopy (FT-IR), Powder X-ray diffraction (PXRD), UV-Diffused Reflectance (UV DRS), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS), and Bruner-Emmet-Teller analyses (BET). Solid-state decomposition kinetics of 1 was performed from Thermogravimetric Analysis (TGA) data by fitting into model equations such as Flynn-Wall-Ozawa (FWO) and corrected (C-FWO).of steps in synthesis, reporting with a lower yield, specific and selectivity, etc. [17]. Copious reports were available with gracious metals such as Pd and Pt catalysts, however, the expensive nature of such metals restrict the common usage [18,19]. Hence, the development of a novel simple methodology for the reductive conversion with selectivity is currently required research area [20]. In this present work, we adopt the simple one-pot synthesis route of title compound by hydrothermal technique.The Polyoxometalates (POM) are metal-oxo clusters of molybdenum, tungsten, and vanadium, etc. attracting considerable interest because of their versatility [21]. The POMs are well known for their usage in multiple fields such as medicine, electronics, magnetism, optics [22], conductance, supramolecular chemistry [23], adsorption [24], antitumor [25], anti-cancer [26], anti-bacterial [27] and catalysis etc. [28]. Usage of POM cluster as a catalyst along with transition metal support in the form of matrix composite could have an added advantage over to either as bare transition metals/plain POM treatment like controlled oxidation, deactivation in air, stopping magnetically induced aggregation, etc. [29][30][31]. It is worth mentioning that in the presence of NaBH 4 the POM has been reported as an efficient reductive catalyst as the reduction concern [32]. In this present work, we report a novel inorganic-organic hybrid composite POM-hybrid (1) material isolated in situ and applied as a reductive catalyst for aromatic nitrophenol derivatives in an aqueous medium.

Tetrahedral Keggin Core Tunes the Visible Light-Assisted Catalase-Like Activity of Icosahedral Keplerate Shell

“…The core–shell clusters, however, proved to be more persistent against H 2 O 2 as evidenced by unaltered XRD patterns (Figure S6). Just a few very weak peaks were detected in the XRD pattern of the used SiMo 12 @K (2θ = 19, 22, 33, and 38°) with no match with the XRD pattern of the core SiMo 12 , ruling out the core release from the capsule caused by the destruction of the core–shell system. These results demonstrate well that the host–guest compounds and particularly PMo 12 @K are much less sensitive to oxidation than those of the K shell clusters.…”

Photocatalytic reduction of mono, di, and tri-nitrophenols over a Bi2MoO6/carbon nitride heterojunction

“…S7, ESI†). 44 However, the photoreduction rate of di- and tri-nitrophenols was lower compared to mono-substituted nitrophenols. A comparative analysis of the photoreduction rates for all three nitrophenols revealed that an increase in the substitution decreased the photocatalytic conversion.…”