Transformative chelation pathways unveiling NiMOF-LDH hybrids on MgO for high-efficiency photocatalysis

Abstract

The significant influence of the sequential addition of EDTA on the growth of NiMOF on an inorganic surface (MgO) was studied. By precisely controlling the sequence of EDTA introduction, we successfully engineered two distinct structures: a highly crystalline and robust NiMOF coating and a NiMg layered double hydroxide (LDH) structure. When EDTA was applied directly to the MgO surface prior to NiMOF formation, a well-adhered, high-performance NiMOF coating was achieved. In contrast, simultaneous or post EDTA introduction resulted in the formation of a NiMg LDH layer. This peculiar behavior, observed for the first time, indicates that EDTA critically influences NiMOF crystallization, either facilitating the formation of a robust NiMOF coating or triggering its breakdown, leading to NiMg LDH formation. Photocatalytic degradation experiments using an organic dye (rhodamine B) and an antibiotic (tetracycline) were conducted to evaluate the effectiveness of the coatings. The results demonstrated that the EDTA addition prior to NiMOF formation yielded the most efficient photocatalyst, degrading 99.2% of Rhd B within just 25 minutes, approximately 6% higher than the next best performer, the NiMOF–EDTA sample. Furthermore, the EDTA–NiMOF coating achieved 90.7% degradation of TC in 120 minutes, significantly surpassing the NiMOF–EDTA sample with a 40% increase in efficiency. In contrast, samples featuring the NiMg LDH structure exhibited markedly lower photocatalytic activity, particularly in the degradation of TC, implying the superior performance of the EDTA–NiMOF complex. This superior photocatalytic activity can be attributed to the higher density of active sites and enhanced adsorption properties of the EDTA–NiMOF complex. This research underscores how synthesis parameters influence the structure and function of hybrid materials, providing insights for designing durable, efficient photocatalysts for environmental remediation.