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Mechano-chemical synthesis of Cu-doped BiVO4 monoclinic nanopowders and investigation of structural, optical and electronic properties.

Results of the simultaneous in-situ UV-vis and open-circuit potential (OCP) monitoring of the low-concentrated aniline (An) polymerization in the presence of camphorsulfonic acid (CSA) suggested that during the induction period (IP) step a transition state formed, which probably included anilinium cation and the oxidant anion, antecedent to a propagation step. No aniline oligomers were registered at this stage but they appeared at the beginning of the propagation step under the investigation conditions. The moments of formation of insoluble pernigraniline phase and appearance of emeraldine units in the growing pernigraniline chains were ascertained by the comparison of kinetic and OCP profiles of the polymerization process both in the solution and in SiC dispersion water mediums. It is deduced that pernigraniline reduction by aniline molecules begins earlier than it is generally accepted (i.e., earlier than OCP maximum is reached) and probably in parallel to a continuing appearance of pernigraniline units even in the same chains that undergo the reduction. It was found that an addition of the SiC dispersion phase into the polymerization mixture accelerates differently all stages of the aniline polymerization. Finally, this polymerization process leads to the formation of polyaniline (PANI)-CSA shell with thickness in the range from 0.5 nm to a few nm at the SiC nanocrystals surface.

Nickel titanate (NiTiO 3 ) thin films were grown by a radio frequency magnetron co-sputtering process using metal (Ni and Ti) targets on fused quartz substrates at a substrate temperature of 400 C. Annealing of asdeposited (amorphous) films was performed at 1100 C for 2 hours to realize a stable crystalline phase. The effect of the Ti target power (200 and 250 W) and nitrogen doping on the structural, morphological and optical properties of post-annealed NiTiO 3 thin films were investigated besides photocatalytic activity under visible light irradiation. X-ray diffraction measurement on the films revealed a pure ilmenite phase at 250 W Ti power. Preferential orientation changed from [104] to [110] as Ti power increased from 200 to 250 W. Raman studies on NiTiO 3 thin films showed almost all the active modes (5A g + 5E g ) of a crystalline structure. Two different microstructures were observed by scanning electron microscopy, films showed rounded (250 nm) grains at 200 W Ti target power while facet forms (500 nm) develop in the films deposited at 250 W. Chemical bonding and valence states of the involved ions such as Ni 2p, Ti 2p and O 1s were investigated by X-ray photoelectron spectroscopy. Nitrogen doping modifies the rms roughness from 12 nm to 17 nm as demonstrated on 200 W grown films and contributes also to modify the indirect optical band gap from 2.50 to 2.43 eV in films obtained at 250 W Ti target power. As a crucial role of nitrogen doping, photocatalytic activity in a broad visible light range was observed with a good efficiency for the degradation of methylene blue by nitrogen doped NiTiO 3 thin films.

The zwitterionic bipyridinium carboxylate ligand 1,1'-bis(4-carboxyphenyl)-4,4'-bipyridinium (pc1) in the presence of cadmium chloride affords novel porous coordination polymers (PCPs): [Cd4(pc1)3Cl6]·CdCl4·guest (1) crystallizing in the P3̅1c space group. In the structure, [Cd4Cl6(CO2)6] building units are linked together by six pc1 ligands, leading to a 3D high-symmetrical network exhibiting hexagonal channels along the c axis. The walls of this PCP consist of cationic electron-acceptor bipyridinium units. The PCP 1 reversibly adsorbs H2O and CH3OH up to about 0.1 g/g at saturation showing the adsorption isotherms characteristic of a moderately hydrophilic sorbent. Adsorption of ammonia (NH3) follows a different pattern, reaching an exceptional uptake of 0.39 g/g (22.3 mmol/g) after the first adsorption cycle. Although the crystalline structure of 1 collapses after the first adsorption, the solid can be regenerated and maintains the capacity of 0.29 g/g (17 mmol/g) in the following cycles. We found that the high NH3 uptake is due to a combination of pore filling taking place below 150 h·Pa and chemisorption occurring at higher pressures. The latter process was shown to involve two phenomena: (i) coordination of NH3 molecules to Cd(2+) cations as follows from (113)Cd NMR and (ii) strong donor-acceptor interactions between NH3 molecules and pc1 ligands.

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