Though CO₂ is a potential carbon source, it has found only a few direct applications so far, and is best known as an environmentally harmful waste ("greenhouse gas"). Its industrial use often implies a preliminary reduction into products of higher added value like CO, formic acid or, preferentially, methanol.^[1] Unfortunately, with carbon in its highest oxidation state, CO₂ is a highly stable molecule (C=O bond: 803 kJ.mol^-1) and its successive reductions require a catalyst for both activation and selectivity. So far, Cu-based catalysts have remained the most popular ones due to their ability to allow CO₂ reduction up to methane, but their good activity is usually at the expense of a low selectivity.

   Contrariwise, molybdenum is a relatively abundant and non-toxic element of which the CO₂ reduction properties have received little attention. However, two recent results have been hinting to its potential as a catalyst: commercial MoO₂ microparticles have been shown to present electrocatalytic CO₂ reduction abilities, especially in the presence of an ionic liquid as co-catalyst,^[2] and some mixed Mo-Bi systems exhibit good selectivity towards methanol, one of the most interesting CO₂ reduction products.^[3]

   This poster will present some of our recent results on the synthesis, characterization and study of the (electro)catalytic properties of different materials prepared by grafting molybdenum-based precursors (Mo(CO)₆, MoCl₅, polyoxomolybdates) on either TiO₂ particles or TiO₂-coated fluorine tin oxide (FTO) electrodes. The CO₂ reduction ability of these systems has been followed by spectroscopy (IR, UV-Vis) and electrochemistry, and the reduction products analyzed by on-line GC and HPLC techniques.

[1] Green Carbon Dioxide: Advances in CO₂ Utilization; G. Centi, S. Parathoner, Eds.; John Wiley & Sons: Hoboken, NJ, 2014.
[2] Y. Oh, X. Hu, Chem. Commun., 2015, 51, 13698.
[3] X. Sun, Q. Zhu, X. Kang, H. Liu, Q. Qian, Z. Zhang, B. Han, Angew. Chem. Int. Ed., 2016, 55, 6771.