Mo-doped Ni-S nanostructure towards energy saving for hydrogen productioncoupling urea oxidation reaction

The growing trend of using energy from fossil fuel sources and the gradual reduction of these sourceshas caused concerns about future energy. Therefore, the need to use clean and renewable sources suchas hydrogen has increased. The synthesis and design of effective electrocatalysts are important togenerate hydrogen via urea electrocatalysis with the minimum required energy. In the present research,Ni-S nanostructure doped with Mo supported on nickel foam substrate were synthesized by facile onestepcyclic voltammetry method and some of the efficient factors such as scan rate, number of cycles,and molybdenum concentration are optimized. The proposed electrode was used as a workingelectrode for urea-assisted electrochemical hydrogen production. The activity and electrocatalyticstability of the prepared electrodes were performed by linear scan voltammetry, cyclic voltammetry,Tafel polarization curve, and chronopotentiometry in ۱ M NaOH and ۰.۳۳ M urea electrolyte. Theresults showed that the optimal electrode (۵۰ mV. s-۱ scan rate and ۱۰ cycles) has an excellentelectrocatalytic activity for hydrogen evolution reaction (HER) equal to -۸۷ mV overpotential at acurrent density of ۱۰ mV.cm-۲. In addition, the optimal electrode showed very good activity for ureaoxidation reaction (UOR) with a potential of ۱.۳۶ V to achieve a current density of ۱۰ mV.cm-۲, whichis due to the high surface-to-volume ratio, maximizing the number of active sites, good electricalconductivity and synergistic effect of elements.