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 (Delta G(H*) = -0.03 eV) at the osmium/silicon interfaces than that on platinum (Delta G(H*) = -0.09 eV) or osmium (Delta G(H*) = -0.26 eV).