My work focuses on the theoretical study of the reactivity of surfaces and nanoparticles related to emblematic reactions in heterogeneous catalysis as Fischer-Tropsch (FTS) or Dry Reforming of Methane (DRM). DFT calculations are my principal tool to model my systems using quantum codes (mostly, VASP, GAUSSIAN, DFTB+ and ADF). My previous studies were applied in the Photo-catalysis of TiO2 surfaces and the modeling of the first step of Fischer-Tropsch reaction on a size range of iron catalysts (Fen). My recent investigations are devoted to the modeling of new catalysts as Metal Phosphide for DRM, the conversion of methane on Pdn@CeO2 core-shell nanoparticles, the study of the binding modes of Citrate to Gold nanoparticles and the generation of nanoalloys for many applications in catalysis (Pt/Au, Pd/Au, Cu/In, Ni/Zn,…).