Thin films of fluorinated 3d-metal phthalocyanines as chemical sensors of ammonia: an optical spectroscopy study

A comparative study of the sensor response toward gaseous ammonia of hexadecafluorinated 3d-metal phthalocyanine (MPcF16, MCu(II), Co(II), Zn(II), Ni(II)) thin films was performed using complementary experimental (viz., surface plasmon resonance, SPR, and IR absorption spectroscopy) along with theoretical (density functional theory calculations, DFT) techniques. SPR measurements revealed changes of both thickness and optical parameters (refraction indices and extinction coefficients) of the MPcF16 films caused by adsorption of NH3. The MPcF16 species studied exhibited the following order of sensor response: ZnPcF16>CoPcF16≥CuPcF16>NiPcF16. A good correlation was found between the DFT calculated (B3LYP/6-311++G(2df,p)) binding energies, experimentally measured shift of the selected IR bands, and the optical sensor response. Apart from this, we performed a detailed assignment of all intense..

VS₂/Graphene Heterostructures as Promising Anode Material for Li-Ion Batteries

Two-layer freestanding heterostructure consisting of VS₂ monolayer and graphene was investigated by means of density functional theory computations as a promising anode material for lithium-ion batteries (LIB). We have investigated lithium atoms’ sorption and diffusion on the surface and in the interface layer of VS₂/graphene heterostructure with both H and T configurations of VS₂ monolayer. The theoretically predicted capacity of VS₂/graphene heterostructures is high (569 mAh/g), and the diffusion barriers are considerably lower for the heterostructures than for bulk VS₂, so that they are comparable to barriers in graphitic LIB anodes (∼0.2 eV). Our results suggest that VS₂/graphene heterostructures can be used as a promising anode material for lithium-ion batteries with high power density and fast charge/discharge rates