Molecular Precursor-Driven Synthesis of Copper Telluride Nanostructures for LIB Anode Application.

Copper tellurides have garnered substantial interest for their applicability as an electrocatalyst for water splitting, battery anodes and photodetectors, etc. Moreover, synthesis of phase pure metal tellurides using the multi-source precursor method is challenging. Therefore, a facile synthesis protocol for copper tellurides is anticipated. The current study involves a simplistic single source molecular precursor pathway for the synthesis of orthorhombic-Cu2.86Te2 nano blocks and -Cu31Te24 faceted nanocrystals employing the [Cu{TeC5H3(Me-5)N}]4 cluster in thermolysis and pyrolysis, respectively. The pristine nanostructures were carefully characterized by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, electron microscopic techniques (scanning electron microscopy and transmission electron microscopy), and diffuse reflectance spectroscopy to know the crystal structure, phase purity, elemental composition, distribution of elements, morphology, and optical band gap. These measurements suggests that the reaction conditions fetch nanostructures of different sizes, crystal structures, morphologies, and band gaps. As prepared nanostructures were evaluated for lithium-ion batteries (LIBs) anode material. The cells fabricated with orthorhombic Cu2.86Te2 and orthorhombic Cu31Te24 nanostructures deliver capacities of 68 and 118 mA h/g after 100 cycles. The LIB anode made up of Cu31Te24 faceted nanocrystals exhibited good cyclability and mechanical stability.

BiPO4: a better host for doping lanthanide ions.

In the present manuscript it is demonstrated that BiPO(4) is a better alternative to lanthanide phosphate host for making lanthanide ion-based luminescent materials. Hexagonal and monoclinic forms of BiPO(4) phase were prepared based on the reaction of Bi(3+) and PO(4)(3-) ions in ethylene glycol medium at 100 and 185 °C, respectively. From the differential thermal analysis (DTA) studies it is confirmed that the difference in the nucleation mechanism rather than the phase transition is responsible for the monoclinic phase formation at low temperatures (125 °C). Monoclinic BiPO(4) is quite stable and forms random solid solutions with lanthanide phosphates having both monoclinic (monazite) and tetragonal (xenotime) structures, as confirmed by XRD, FTIR and (31)P solid state nuclear magnetic resonance studies. On excitation corresponding to the (1)S(0)→(3)P(1) transition of Bi(3+) in BiPO(4):Ln samples, energy transfer from host to lanthanide ions takes place. The studies are quite relevant as there is a growing interest all over the world in replacing lanthanide based host used for different applications with easily available, easily purifiable and cheap main group elements (like Sb, Bi etc.) based hosts.