In‐Situ Constructing Eosin Y Sensitized Cs₂PtSnCl₆ Perovskites for Enhanced Photocatalytic Hydrogen Evolution

Abstract Vacancy‐ordered Cs 2 SnX 6 perovskites, with low‐toxicity and high stability, have emerged as promising photocatalysts for hydrogen evolution reaction (HER). However, most Cs 2 SnX 6 and derivatives have low catalytic activity mainly due to their insufficient light utilization efficiency. Herein, a simple in situ method is introduced to sensitize Cs 2 PtSnCl 6 with Eosin Y (EY), forming EY‐Cs 2 PtSnCl 6 for HER in aqueous solution. Various characterizations indicate that the EY is immobilized onto the Cs 2 PtSnCl 6 during the synthesis process. The EY‐Cs 2 PtSnCl 6 displayed extended light absorption range and efficient charge transfer from EY to Cs 2 PtSnCl 6 . The resulting EY‐Cs 2 PtSnCl 6 material exhibits high HER rate of 17.6 mmol g −1 h −1 , ≈1760 folds than that of the pristine Cs 2 PtSnCl 6 . This work demonstrates an effective method to construct dye‐sensitized perovskites and highlights the importance of interaction between dye and perovskite. It provides useful guidance for the design of new perovskite‐based photocatalysts and it will advance the development of perovskites for solar energy conversion into renewable fuels.