Theoretical Expectation and Experimental Implementation of In Situ Al-Doped CoS2 Nanowires on Dealloying-Derived Nanoporous Intermetallic Substrate as an Efficient Electrocatalyst for Boosting Hydrogen Production

Abstract

Foreign atom doping is known to not only modify the electronic structure but also improve the intrinsic activity of catalysts. Herein, we fabricate three-dimensional (3D) self-supporting nanoporous cobalt–aluminum intermetallic (np-Co(Al)) through dealloying of Al90Co10 master alloy to in situ introduce Al element into the precursor. The intrinsic Al dopant is determined to be insensitive to S vapor but beneficial to generate numerous Al-doped CoS2 nanowires (Al-CoS2 NWs) when they were subjected to solid–vapor sulfurization treatment. The density functional theory (DFT) calculations evidence that spontaneous Al-doping in CoS2 crystal could enhance the hybridization between Co d-orbital and S p-orbital near the Fermi level. On the one hand, the Co-sites are more active than that of the S-sites, and the intermediate hydrogen (H*) adsorption free energy (ΔGH*) of Al-CoS2 is only −0.16 eV when adsorbed on the bridge site of Co. On the other hand, the embedded Al can not only facilitate the activity improveme...