Efficient photocatalytic NO oxidation over novel NiAl layered double hydroxide/Bi4Ti3O12 Z-scheme heterojunctions with boosted charge separation and O2 activation

Abstract

Suffering from inefficient carrier migration and the lack of active sites, the effective photocatalytic removal of low-concentration NO is still a formidable challenge. In this work, a NiAl-LDH/Bi₄Ti₃O₁₂ Z-scheme heterojunction photocatalyst was prepared successfully through a facile two-step hydrothermal procedure. In this, the Fermi-level difference at the interface of Bi₄Ti₃O₁₂ and NiAl-LDH results in the formation of a strong built-in electric field (BIEF). The strong BIEF enables the formation of a Z-scheme heterojunction, offering a novel charge transfer pathway that promotes the efficient migration of photogenerated electrons and holes while retaining their strong redox capability. Additionally, the unique NiAlLDH-modified sheet-like stacked nano-flower structure has a large specific surface area, which is beneficial for semiconductor absorption of sufficient photons to increase the concentration of charge carriers, and providing more reaction sites for the adsorption and activation of oxygen, thereby generating more reactive oxygen species. As a result, the optimized NiAl-LDH/Bi₄Ti₃O₁₂ catalyst exhibits enhanced photocatalytic NO removal efficiency (75.51%), which significantly surpasses that of pristine Bi₄Ti₃O₁₂ (62.35%) and NiAl-LDH (5.12%). The findings of this research offer insights into the rational development of Bi₄Ti₃O₁₂-based heterostructure photocatalysts for air purification.