Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe2 photocatalyst

Systematically study of in-plane intrinsic defects and edge atoms is important to guide the design of low-dimensional photocatalysts. Here the authors investigate photocatalytic CO2 reduction to CH4 over reconstructed edge atoms of monolayer semiconducting WSe2. Ascertaining the function of in-plane intrinsic defects and edge atoms is necessary for developing efficient low-dimensional photocatalysts. We report the wireless photocatalytic CO2 reduction to CH4 over reconstructed edge atoms of monolayer 2H-WSe2 artificial leaves. Our first-principles calculations demonstrate that reconstructed and imperfect edge configurations enable CO2 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 WSe2-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 CO2 reduction reactions.

Automated summary

Systematic study of in-plane intrinsic defects and edge atoms is important for the design of low-dimensional photocatalysts. This study investigates the photocatalytic CO2 reduction to CH4 over reconstructed edge atoms of monolayer semiconducting WSe2. The results demonstrate that the consumed electron rate per edge atom is higher than the in-plane intrinsic defects, and nanoscale redox mapping confirms that the edge is the preferred region for charge transfer. These findings pave the way for designing a new class of monolayer transition metal dichalcogenides as non-precious co-catalysts for hydrogen evolution or CO2 reduction reactions.