Topological insulator path toward efficient hydrogen evolution catalysts in the Li2Pt family

Topological materials, such as topological semimetals and topological insulators, with robust topological surface states have bright application prospects in electrochemical catalysis. Here, the first-principles calculations indicate the strong topological insulator ${\mathrm{Li}}_{2}\mathrm{Pt}$ family promotes efficient catalytic response to the hydrogen evolution reaction. For ${\mathrm{Li}}_{2}\mathrm{Pt}$ and ${\mathrm{Li}}_{2}\mathrm{Pd}$, the calculated Gibbs free energy $\mathrm{\ensuremath{\Delta}}{G}_{{\mathrm{H}}^{*}}$ of the bridge site is 0.054 eV and 0.041 eV, while that for the top site is 0.187 eV and 0.641 eV, respectively. The better hydrogen evolution reaction performance of the bridge site can ascribe to H hybridizes with the ${d}_{xy}+{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbital, which donates the nontrivial topological surface states, while H hybridizes with the ${d}_{{z}^{2}}$ orbital that withholds contribution to topological surface states for the top site. Noticeably, the $\mathrm{\ensuremath{\Delta}}{G}_{{\mathrm{H}}^{*}}$ of the bridge site for ${\mathrm{Li}}_{2}\mathrm{Pt}$ (0.054 eV) and ${\mathrm{Li}}_{2}\mathrm{Pd}$ (0.041 eV) is nearly half of the value of Pt (0.09 eV), indicating an excellent hydrogen evolution reaction activity. This work uncovers the hybridization between adsorbate and topological surface states plays a vital role in enhancing the hydrogen evolution reaction performance and provides a promising route to design topological quantum catalysts.