Os/Si nanocomposites as excellent hydrogen evolution electrocatalysts with thermodynamically more favorable hydrogen adsorption free energy than platinum

The development of highly efficient electrocatalysts for hydrogen evolution reaction is a fundamental undertaking of the hydrogen economy . Herein, we investigated the electrocatalytic performance of M/Si (M = Os, Rh, Pt, Pd, Re, Ru, Au or Ag) nanocomposites for hydrogen evolution reaction. The results show that Os/Si nanocomposites exhibit the best catalytic efficiency with a negligible onset overpotential (−25   mV), a small Tafel slope of −24   mV   dec −1 and remarkable long-term stability. Of most importance, at a current density of the typical industrial production (−1000   mA   cm −2 ), the energy conversion efficiency of the Os/Si nanocomposite is 29.3% higher than that of the commercial 40   wt% Pt/C. The density functional calculations reveal that such outstanding catalytic activity of the Os/Si catalyst arises from the thermodynamically more favorable hydrogen adsorption free energy (Δ G H* = −0.03   eV) at the osmium/silicon interfaces than that on platinum (Δ G H* = −0.09   eV) or osmium (Δ G H* = −0.26   eV).