Efficient spatial charge separation in the Ruddlesden-Popper phase-based S-scheme Fe₂SnO₄-g-C₃N₄ heterojunction for visible light-induced H₂ generation

A Ruddlesden-Popper (RP)-based Fe₂SnO₄ (FSO) perovskite was coupled with g-C₃N₄ (gCN) to fabricate an S-scheme heterojunction. The intimate heterojuction is formed by anchoring the FSO particles over gCN using ultrasonication followed by calcination. The internal electric field generated post-catalyst copuling faciliates the isolation and directional movement of photogenerated charge carriers. The FSO-gCN heterojunction with the S-scheme configuration shows a good light-harvesting capability and provides a significant number of active sites. The photocatalyst generated an impressive hydrogen rate of 1204 μmol g⁻¹ h⁻¹. This rate is 3.7 and 133 times greater than that by gCN and FSO alone, respectively. Furthermore, the heterojunction shows an excellent photostability, experiencing only a marginal decrease in activity over 4 cycles. Such an improved photocatalytic performance is ascribed to the S-scheme charge transfer mechanism, corroborated by XPS analysis and radical trapping test. This study is instructive for the design of an efficient RP-based stannate S-scheme heterojunction for many photochemical reactions.