C. Boulanger

Molybdenum cluster chalcogenide electrochemistry—I. Potentiodynamic study of topotactic insertion reactions

Abstract The insertion/de-insertion topotactic reactions in the Chevrel-type molybdenum cluster chalco-genides Mo6X8 (X = S, Se) are studied in the potentiodynamic mode on crystallite bed electrodes. We define the best conditions for the identification of the successive steps of the insertion (MxMo6X8). The phenomenon of the cation diffusion in the host lattice is responsible for the voltamperogram features.

Molybdenum cluster chalcogenide electrochemistry—III. Study of cadmium insertion into the host-lattices MoyXz

Abstract The insertion of the Cd2+ cation is studied by the potentiodynamic way in the case of the Chevrel Mo6X8phases (X = S, Se, Te) and the condensed cluster phases MoyXz. The voltamperogram analysis allows different redox systems to be classified. Comparison of the results does not give evidence for a simple relationship with the parameters governing the insertion phenomena.

Molybdenum cluster chalcogenide electrochemistry—II. Determination of the insertion system normal potentials from the analysis of the i = f(E) curves in the potentiodynamic way

Abstract In the electrochemical study of the topotactic insertion/de-insertion reactions, the behaviour of the crystallite-bed electrodes have been considered from a theoretical point of view. The diffusional models give evidence that the normal potential of the M n + , Mo y X z /M x Mo y X z system can be determined by using a potentiodynamic method.

Biosourced polymetallic catalysis : a surprising and efficient means to promote the Knoevenagel condensation

Zn hyperaccumulator (Arabidobsis halleri) and Zn accumulator Salix “Tordis” (Salix schwerinii × Salix viminalis) have shown their interest in the phytoextraction of polluted brownfields. Herein, we explore a novel methodology based on the chemical valorization of Zn-rich biomass produced by these metallophyte plants. The approach is based on the use of polymetallic salts derived from plants as bio-based catalysts in organic chemistry. The formed ecocatalysts were characterized via ICP-MS, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) in order to precise the chemical composition, structure, and behavior of the formed materials. The Doebner-Knoevenagel reaction was chosen as model reaction to study their synthetic potential. Significant differences to usual catalysts such as zinc (II) chloride are observed. They can principally be related to a mixture of unusual mineral species. DFT calculations were carried out on these salts in the context of the Gutmann theory. They allow the rationalization of experimental results. Finally, these new bio-based polymetallic catalysts illustrated the interest of this concept for green and sustainable catalysis.