Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe(2) photocatalyst

Ascertaining the function of in-plane intrinsic defects and edge atoms is necessary for developing efficient low-dimensional photocatalysts. We report the wireless photocatalytic CO(2) reduction to CH(4) over reconstructed edge atoms of monolayer 2H-WSe(2) artificial leaves. Our first-principles calculations demonstrate that reconstructed and imperfect edge configurations enable CO(2) binding to form linear and bent molecules. Experimental results show that the solar-to-fuel quantum efficiency is a reciprocal function of the flake size. It also indicates that the consumed electron rate per edge atom is two orders of magnitude larger than the in-plane intrinsic defects. Further, nanoscale redox mapping at the monolayer WSe(2)–liquid interface confirms that the edge is the most preferred region for charge transfer. Our results pave the way for designing a new class of monolayer transition metal dichalcogenides with reconstructed edges as a non-precious co-catalyst for wired or wireless hydrogen evolution or CO(2) reduction reactions.