Schottky junction coupling with metal size effect for the enhancement of photocatalytic nitrate reduction

Abstract

Nitrate pollution poses a significant environmental challenge, and photocatalytic nitrate reduction has garnered considerable attention due to its efficiency and environmental advantages. Among these, the development of Schottky junctions shows considerable potential for practical applications. However, the impact of metal nanoparticle size within Schottky junctions on photocatalytic nitrate reduction remains largely unexplored. In this study, we propose a novel method to modulate metal nanoparticle size within Schottky junctions by controlling light intensity during the photodeposition process. Smaller Au nanoparticles were found to enhance electron accumulation at active sites by promoting charge transfer from COF to Au, thereby improving internal electron transport. Additionally, the Schottky barrier effectively suppressed reverse electron transfer while enhancing NO₃^– adsorption and activation. The Au₂-COF exhibited remarkable nitrate reduction performance, achieving an ammonia yield of 382.48 μmol g^–1 h^–1, 5.7 times higher than that of pure COF. This work provides novel theoretical and practical insights into using controlled light intensity to regulate metal nanoparticle size within Schottky junctions, thereby enhancing photocatalytic nitrate reduction.