Synthesis of High-Performance Ru-doped MoSe₂ Heirarchical Nanoflowers for Hydrogen Evolution Reaction

Hydrogen production using a stable, cost-effective and earth abundant catalyst via electrochemical and photochemical water-splitting has received enormous research interest in recent years. Two dimensional layered materials, such MoS₂, WS₂ and MoSe₂, are efficient catalyst electrode material for electrochemical hydrogen evolution reaction (HER). It has been reported that the catalytic activity of these materials originates from the active edge sites, while Basel plane electrically and chemically remains inert. Therefore, syntheses of MoS₂ and MoSe₂ novel nanostructures have effective active edge sites with enhanced HER activity are greatly appreciate. In the present study, Ru doped MoSe₂ 3D heirarchical nanoflowers were synthesized using colloidal method and the HER activity of the catalyst was investigated as a function Ru atomic percentage. Flower-like structure was stabilized in Mo_1-xRu_xSe₂ samples for different x values (x= 0, 0.075, 0.11, 0.18 and 0.3) and the sizes were spanning in the range 500-200 nm respectively. X-ray diffraction (XRD) pattern revealed that the Ru-doped MoSe₂ nanoflowers were crystallized into 2H-hexagonal crystal structure. Optical excitons A and B show red shift in absorption spectra with increasing Ru atomic percentage. Mo_1-xRu_xSe₂ samples shows improved electrochemical catalytic activity with Ru doping, in which undoped MoSe₂ nanoflower exhibits an over potential of 245 mV and Tafel slope of 65 mV/dec. These values reached to minimum of 165 mV and 46 mV/dec for Mo_1-xRu_xSe₂ of x=0.18 respectively.