Atomic Sandwiched p‐n Homojunctions

Abstract Semiconductor p‐n junctions have been explored and applied in photoelectrochemical (PEC) water splitting, but serious carrier recombination and sluggish oxygen evolution reaction (OER) dynamics have demanded further progress in p‐n junction photoelectrode design. Here, via a controllable NH 3 treatment, we construct sandwiched p‐n homojunctions in three‐unit‐cells n‐type SnS 2 (n‐SnS 2 ) nanosheet arrays using nitrogen (N) as acceptor dopants. The optimal N‐doped n‐SnS 2 (pnp‐SnS 2 ) with such unique structure achieves a record photocurrent density of 3.28 mA cm −2 , which is 21 times as high as that of n‐SnS 2 and the highest value among all the SnS 2 photoanodes reported so far. Moreover, the stoichiometric O 2 and H 2 evolution from water was achieved with Faradaic efficiencies close to 100 %. The superior performance could be attributed to the facilitated electron–hole separation/transfer, accelerated surface OER kinetics, prolonged carrier lifetime, and improved structural stability.