Ammonium fluoride mediated mechanochemical synthesis of A2MF6 (A=K, Rb; M=Pd, Mn, Ni) along with their catalytic role in environmental remediation

6^th International Conference and Exhibition on Materials Science and Chemistry

May 17-18, 2018 | Rome, Italy

Pooja Rawat and Rajamani Nagarajan

University of Delhi, India

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

Bond breaking and bond making triggered by stress are usually referred to as mechanochemical reactions. To highlight the power of mechanochemistry to oxidize metal ions leading to the discovery of newer phases, ammonium fluoride mediated synthesis of A2MF6 (A=Rb, K; M=Pd, Mn, Ni) has been carried out. Stability of high oxidation state of transition elements using mechanochemical approach has been demonstrated. Grinding reactions of ammonium fluoride with metal (II) acetate and further cation exchange with AF (A=Rb, K) were closely monitored ex-situ characterizations such as high resolution powder xâ�?ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy measurements. For the reaction involving AF (A=Rb, K), A2MF6 possessing K2PtCl6 type structure was confirmed from the Rietveld refinement of PXRD pattern, high-resolution transmission electron microscopy (HR-TEM) and selectedâ�?area electron diffraction (SAED) measurements. Elemental composition and oxidation state of palladium in Rb2PdF6 were examined using x-ray photoelectron spectroscopy (XPS) analysis. Ligand to metal charge transfer and d-d transitions of Pd(IV) were present in the UV-visible diffuse reflectance spectrum of Rb2PdF6 with a band gap of 2.67 eV estimated using the Kubelkaâ�?�?Munk function. Other than ligand-to-metal charge-transfer (LMCT), they also show a broad band in visible region for d-d transitions. Its role as a photocatalyst to degrade the aqueous dye solutions (MB, RhB, Rh6G and MG) under UV-visible radiation has been evaluated along with their kinetic studies. The reduction of Pd(IV) to Pd(0) by NaBH4 has been favourably used for the efficient and rapid conversion of highly carcinogenic, toxic, mutagenic Cr6+ to less toxic Cr3+. Application of Mn4+ in K2MnF6 as red phosphors has been demonstrated by using PL spectroscopy. poojarawatchemistry@gmail.com