Microwave-Assisted Coprecipitation Synthesis and Local Structural Investigation on NiO, ß-Ni(OH)2/Co3O4 Nanosheets, and Co3O4 Nanorods Using X-ray Absorption Spectroscopy at Co-Ni K-edge and Synchrotron X-ray Diffraction.

Developing the most straightforward, cheapest, and eco-friendly approaches for synthesizing nanostructures with well-defined morphology having the highest possible surface area to volume ratio is challenging for design and process. In the present work, nanosheets of NiO and ß-Ni(OH)2/Co3O4, and nanorods of Co3O4 have been synthesized at a large scale via the microwave-assisted chemical coprecipitation method under low temperature and atmospheric pressure. X-ray absorption spectroscopy (XAS) measurements, which comprises both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques, have been carried out at Co and Ni K-edges to probe the electronic structure of the samples. Also, the local atomic structural, chemical bonding, morphological, and optical properties of the sample were systematically investigated using XAS, synchrotron X-ray diffraction (SXRD), Raman spectroscopy, FTIR, transmission electron microscopy (TEM), and UV-visible spectroscopy. The normalized XANES spectra of the ß-Ni(OH)2/Co3O4 nanosheets show the presence of Ni2+ and a mixed oxidation state of Co. The disorder factor decreases from ß-Ni(OH)2/Co3O4 to Co3O4 with increasing Co-O bond length. The SXRD pattern analyzed using Rietveld refinement reveals that NiO has a face-centered cubic phase, Co3O4 has the standard spinal structure, and ß-Ni(OH)2/Co3O4 has a mixed phase of hexagonal and cubic structures. TEM images revealed the formation of nanosheets for NiO and ß-Ni(OH)2/Co3O4 samples and nanorods for Co3O4 samples. FTIR and Raman spectra show the formation of ß-Ni(OH)2/Co3O4, which reveals the fingerprints of Ni-O and Co-O.

Single Mn Atom Doping in Chiral Sensitive Assembled Gold Clusters to Molecular Magnet.

Chiral stirred optical and magnetic properties, through the doping of assembled ultrasmall metal clusters (AMCs), are promising discernment to rivet the molecule-like quantum devices. Here, the single manganese (Mn) atom doping and assembly of the gold cluster (Au8), leading to the chirality driven magnetism, has been achieved through a ligand-mediated growth. The X-ray absorption near edge structure and electron paramagnetic resonance studies corroborate the tetrahedral coordinated local structure of Mn dopant in the Au host. The optical and vibrational circular dichroic analysis affirms the modulation of chirality (negative to positive) in the presence of the Mn. A distinct ferromagnetic hysteresis loop at 300 K shows Mn ridden chiral sensitive ferromagnetism in contrary to the ligand influenced superparamagnetic undoped AMCs. The spin-polarized density functional theory level of calculations reveal the partial overlapping of spin-up and -down density of states in the doped AMCs, attributing to the ferromagnetic nature as like a molecular magnet suitable for the opto-spintronics application.