Synthesis and characterization of MXene-based matreials advanced : application to water electrolysis in alkaline media ; Synthèse et caractérisation de matériaux à base de MXène : application à l'électrolyse de l'eau en milieu alcalin

Hydrogen is an energetic vector pointed out to replace fossil fuels. It is being considered for large-scale application in H2/O2 fuel cells. However, it is necessary to produce it at a very high degree of purity and under environmentally friendly conditions. The most efficient way to produce pure "green" hydrogen is water electrolysis, which implies the development of low-cost, active and stable electrodes. In particular, it is required to develop new efficient catalysts that are free from expensive and/or rare noble metals. Nanostructuring of materials is an approach that is increasingly explored to satisfy the above-mentioned criteria. In particular, 2D materials with high electronic conductivity are very promising as they generally present very high specific surface areas and electronic and/or catalytic properties different from their bulk counterparts. Among this material class, transition metal carbonitrides called MXenes and discovered in 2011, have been attracting a growing interest because of their intrinsic characteristics (chemical versatility, very high conductivity, hydrophilicity), which provide them suitable properties for a wide range of applications.In this thesis, MXenes of formula Mn+1XnTx were either synthesized from the corresponding MAX phase Mn+1AXn (where M is titanium and/or molybdenum, A is aluminum and X is carbon and/or nitrogen), or from Mo2Ga2C by exfoliation of aluminum or gallium by acid etching. Firstly, particular attention was paid to the influence of the composition of the exfoliation medium in order to control both the nature of T (terminal groups on the surface of MXenes resulting from the exfoliation process), the nature of the species intercalated between sheets, the structure, the macrostructure, the surface oxidation degree and the state of delamination. The influence of M element in MXene on its electrocatalytic properties was studied by preparing Ti/Mo mixed MXenes. Another study focused on the influence of the X element, by partially or totally substituting carbon for ...