Constructing Layered Double Hydroxide‐Based Micro‐Nano Reactors for Enhanced Nitrogen Photofixation

ABSTRACT Efficient photofixation of N 2 in aqueous photocatalyst dispersions is hampered by the very low solubility and diffusion coefficient of N 2 in water. Herein, we designed and constructed 3D micro‐nano reactors based on zinc‐aluminum layered double hydroxide (3D‐LDH) to overcome these challenges. Notably, the unique spatial architecture of the micro‐nano reactors (containing vertical ZnAl‐LDH arrays) visually captured by confocal laser scanning microscopy enriches the local concentration of small gas molecules during photocatalysis. The spillover kinetic analysis using oxygen as a probe molecule verified the enhanced diffusion of small gas molecules in the local vicinity of the 3D‐LDH catalyst. Accordingly, 3D‐LDH delivered superior photocatalytic activity for nitrogen photofixation compared to traditional LDH photocatalysts (2D‐LDH and bulk‐LDH). As a demonstration of the universality of this approach, 3D‐BiOBr and 3D‐TiO 2 equipped with micro‐nano reactors were also prepared, demonstrating notably enhanced performance for photocatalytic H 2 O 2 synthesis and aqueous dye degradation compared to their 2D counterparts. This work thus identifies a practicable strategy for enhancing the rates of photocatalytic reactions in aqueous media that utilize a gas‐phase reactant.