Efficient hydrogen evolution reaction due to topological polarization

Materials carrying topological surface states (TSS) provide a fascinating platform for the hydrogen evolution reaction (HER). Based on systematic first-principles calculations ${A}_{3}B$ ($A$ = Ni, Pd, Pt; $B$ Si, Ge, Sn), we propose that electric polarization characterized by Zak phase can be crucial to designing efficient catalysts HER. For ${A}_{3}B$, show takes nontrivial value of $\ensuremath{\pi}$ in whole (111) projected Brillouin zone, which causes quantized charges at surface. There, depending adsorption sites, (H) atom hybridizes with TSS rather than bulk states. When hybridization has an intermediate character between covalent and ionic bonds, H are localized energy spectrum, change Gibbs free ($\mathrm{\ensuremath{\Delta}}G$) due becomes small. Namely, interaction substrate considerably weak, is highly favorable situation Notably, $\mathrm{\ensuremath{\Delta}}G$ ${\mathrm{Pt}}_{3}\mathrm{Sn}$ ${\mathrm{Pd}}_{3}\mathrm{Sn}$ just $\ensuremath{-}0.066$ $\ensuremath{-}0.092$ eV, respectively, almost half Pt.