Robust Polarized Fields Generated by Organic–Inorganic Hybrid Perovskite Ferroelectrics Crystallization for Boosting Hydrogen Production Activity

ABSTRACT Using sunlight and water to get hydrogen (H ₂ ) offers a promising pathway toward a sustainable future. Severe recombination of photogenerated electron–hole pairs directly impedes photocatalytic H ₂ production, while the strong polarized field from ferroelectric materials has been demonstrated to effectively promote charge separation. However, several drawbacks still remain, such as low piezoelectric coefficient, difficulty in forming a polarized field, and complex calcination preparation process. Herein, we present an in situ heterogeneous nucleation crystallization strategy for organic‐inorganic hybrid perovskite ferroelectrics, involving heterogeneous crystallization on the surface of solid photocatalyst, the emanation of a polarized field, and the enhancement of photocatalytic H ₂ production. Under the mechanical stimulus, a polarized field is generated with deformation of the molecular ferroelectrics, which reinforces the charge separation efficiency. Thus, photocatalytic H ₂ production increases to 6.725 mmol g ⁻¹ h ⁻¹ , almost 26‐fold compared to the control C ₃ N ₄ catalyst (0.255 mmol g ⁻¹ h ⁻¹ ). Our work demonstrates the extensive application of molecular ferroelectrics for high performance photocatalyst design with enhanced photocharge separation.