Mesoporous Strontium Hydroxide Hydrate As a Nanostructure-Dependent Electrocatalyst for Hydrogen Evolution Reaction

Tremendous efforts have been directed to developing reliable electrocatalysts to gain clean hydrogen energy from water splitting and encounter energy challenges. The morphology at the nanoscale of electrocatalysts has also a significant influence on hydrogen evolution reaction. An alkaline-based electrocatalyst, strontium hydroxide hydrate, has been synthesized at temperatures of 80, 140, and 200 degrees C using the hydrothermal process. The employed growth temperature capably influences the morphology and intrinsic characteristics of the strontium hydroxide hydrate for the hydrogen evolution reaction. The mesoporous nature, greater electrochemical and specific surface area of nanorods, and facile proton donation by the acid jointly enhance the HER activity. Hy-Sr(OH)2-200 nanorods have exhibited a good overpotential of 84 mV in 0.5 M H2SO4 at the current density of 10 mA cm-2, which is better than the nanopallets (Hy-Sr(OH)2-80) and the hybrid morphology consisting of nanopallets and nanorods (Hy-Sr(OH)2-140). The mesoporous nature, greater electrochemical and specific surface area, and nanorod-like morphology have promoted and facilitated the adsorption and desorption of the active hydrogen atoms at the active sites inside the Hy-Sr(OH)2-200 nanorods. As a result, Hy-Sr(OH)2-200 nanorods exhibit the Tafel slope of 81 mV dec-1 in 0.5 M H2SO4 and follow the Volmer-Heyrovsky phenomena. Moreover, Hy-Sr(OH)2-200 nanorods show a good turnover frequency of 142.84 ms-1 at the fixed reversible hydrogen potential of 0.5 V, which is better than the other employed electrolytes and electrocatalysts fabricated at temperatures of 80 and 140 degrees C. The symmetric system, consisting of HySr(OH)2-200 nanorods, shows a good overpotential of 240 mV at a current density of 10 mA cm-2, along with a Tafel slope of 79 mV dec-1 in 0.5 M H2SO4. The electrocatalyst of Hy-Sr(OH)2-200 nanorods comprehensively exhibits good performance for the hydrogen evolution reaction.