The role of precursors in MoSe₂ nanoflowers growth mechanism

Nanoflowers have unique morphology of exposed edges that is one of the most promising morphologies for catalysis. Modifying the synthesis of MoSe₂ can change properties such as morphology, crystallinity, average particle size and catalytic activity. In this project 3 different synthesis protocols were used in order to study the correlation between different precursors and the final morphology and the resulting effect on the catalytic performance of HER. The protocols included the following precursors combinations: I) Na₂MoO₄∙2H₂O/ ODE-Se, II) MoO₂(acac)₂/ ODE-Se, and III) MoO₂(acac)₂/ DBDSe. Moreover, additional parameters such as the feed ratio between Se and Mo and the reaction duration were varied in order to systematically study the effect of crystallinity and stoichiometry over the catalytic performance towards the HER. The characterized samples show connection between reaction time and average size of particles and crystallinity. Not all precursors combinations resulted in the nanoflower structure. The combination that showed the best results is Na₂MoO₄∙2H₂O/ODE-Se where the particles are bigger than the other two precursors combination. The Na₂MoO₄∙2H₂O/ODE-Se exhibit low Tafel slope values (54-68 mV/dec) and low overpotentials of 0.221-0.245 mV. In this project, various MoSe₂ structures were produced and fully characterized to gain insights into the growth mechanism and the final products’ applicability to serve as HER catalysts.