Two birds, one stone: Rational design of Bi-MOF/g-C3N4 photocatalyst for effective nitrogen fixation and pollutants degradation

Abstract

With the goal of transforming wastewater into suitable irrigation water, the combined approach of pollutant degradation and nitrogen fixation holds immense potential. This strategy not only purifies water by removing contaminants but also supplies vital nitrogen fertilizer nutrients to crops. However, designing a photocatalyst with efficient photocatalytic activity is a significant challenge. In our study, we present a novel composite photocatalyst, featuring a bismuth-based metal-organic framework (Bi-MOF) and graphitic carbon nitride (g-C3N4). This composite exhibits remarkable performance in pollutants degradation and ammonia production. The complex multi-channeled interior of Bi-MOF facilitates effective N2 or organic molecule adsorption, while g-C3N4 generates abundant photocarriers in response to visible light. The hetero-interface between Bi-MOF/g-C3N4 ensures efficient photocarriers separation. Notably, ammonia yield achieved 209.96 μmol h−1 gcat−1 and 168.56 μmol h−1 gcat−1 in Rhodamine B and glyphosate solutions, respectively, under air bubbling, surpassing levels in N2-fed pure water by 1.8 and 1.5-fold. Optimal Rhodamine B and glyphosate degradation rates stood at 0.3496 min−1 and 0.0067 min−1. This study offers valuable insights for transforming polluted water into clean, nutrient-rich agricultural irrigation water, addressing crucial sustainability concerns.