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

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 NA/Vs) 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 (Delta G(H)*) 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 improvement of Co-sites but also greatly activate the inert S-sites in CoS2. An overpotential as small as 86 and 191 mV to reach 10 and 100 mA cm(-2) H-2-evolving current, a small Tafel slope of 62.47 mV dec(-1), and long-term operational stability are achieved on the AI doped CoS2 catalyst. This finding opens up an easily accessible in situ doping route via alloying-dealloying followed by inheritance to nanoporous earth-abundant chalcogenide electrocatalyst for regulating their physicochemical and electrochemical properties, accelerating the development of high performance H-2-evolving electrode for electrochemical hydrogen production.