Surface defect engineering toward efficient photocatalytic NO removal

Abstract

Anthropogenic emissions of nitrogen oxides (NO_x, primarily NO) from industrial production, agriculture, and transportation persistently threaten human health and ecosystems. Although selective catalytic reduction technology has proven effective in NO_x abatement, achieving green purification with lower energy consumption and reduced carbon emissions remains a significant challenge. Against this backdrop, photocatalysis emerges as a sustainable alternative, as it utilizes sunlight to generate high-energy electron-hole pairs in semiconductors, enabling the abatement and valorization of NO_x under mild conditions. Building upon existing reviews that survey broad modification strategies, this minireview delves specifically into surface defect engineering for photocatalytic NO_x elimination, exploring the distinct roles of tailored defect types and their structure-activity relationships as a complement to the broader discourse. We first elaborate on the fundamental mechanisms of photocatalytic NO abatement, covering the photooxidation of NO to NO₃^– and its photoreduction to N₂/NH₃. We then discuss the role of surface defect engineering (e.g., surface vacancies, heteroatom doping, and structural distortions) in enhancing the performance of semiconductor-based photocatalysts (e.g., g-C₃N₄, TiO₂, Bi-based materials) for NO removal. Finally, we present perspectives on the future challenges of defect-containing photocatalysts in this field. We anticipate that this minireview will inspire the rational design of advanced defective photocatalysts, facilitating the efficient and selective conversion of NO.