Instantaneous and Continuous Construction of Perovskite Heterojunctions with Intensified Built‐in Electric Field for Efficient Photocatalytic CO ₂

Abstract Enhancing the built‐in electric field (BIEF) in heterojunctions remains a pivotal challenge for developing efficient photocatalysts. Herein, a high‐gravity‐assisted approach utilizing rotating packed bed (RPB) is proposed to instantaneously and continuously construct Cs ₃ Bi ₂ Br ₉ /TiO ₂ (CBB/TiO ₂ ) heterojunctions with intensified BIEF, intimate interfacial contact, and accelerated charge‐transfer kinetics, overcoming the constraints of traditional electrostatic self‐assembly techniques. Compared to the counterpart of batch‐type stirred tank (ST), the optimized heterojunction exhibits a 1.8‐fold elevation in surface charge density and a 2.3‐fold enhancement in BIEF strength, offering a robust driving force for directional charge‐transfer. These advancements result in remarkable carbon dioxide (CO ₂ ) photoreduction performance, achieving a high CO production rate of 259 µmol g ⁻¹ h ⁻¹ , which is 1.5 times higher than that of ST, 3.6 and 6.0 times exceeding both pristine components. Mechanistic investigations indicate that the enhanced activity stems from ameliorated charge carrier separation and transport at the high‐quality interface. The generality of this approach is corroborated through successful extension to CBB/ZnO (1.92‐fold BIEF enhancement) and CBB/CuO (2.04‐fold) systems. This study establishes high‐gravity engineering as a potent platform for the fabrication of high‐performance photocatalytic heterojunctions.