63079 2025 eng 2255 2265 8 7 article Royal Society of Chemistry 1 -- -- -- Metal–organic frameworks (MOFs) have attracted increasing attention for the removal of organic pollutants in wastewater via photocatalysis. Here, we design a multivariate modification of ZIF-9 to tune its electronic properties for use in visible light photocatalysis. A controllable synthesis of ZIF-9 and its multivariate forms with the incorporation of copper and the 2-imidazolecarboxaldehyde (ica) ligand was carried out. The materials are tested for the removal of the model dye methylene blue (MB) by a heterogeneous photo-Fenton-like reaction at neutral pH and room temperature. Cu-ZIF-9-ica (UPO-3) shows high photocatalytic activity under both visible and ultraviolet A (UVA) light, achieving 94% MB degradation in 45 min, compared to 65% MB degradation in 120 min using bare ZIF-9. The study revealed a first-order rate constant of 0.0475 min−1 for Cu-ZIF-9-ica compared to 0.0088 min−1 for ZIF-9 under visible light. The improvement of the catalyst was clearly attributed to the co-incorporation of Cu and the ica ligand in the MOF, which reduces the band gap, in agreement with DFT calculations. Reproducibility and recyclability tests proved that Cu-ZIF-9-ica can be used for at least 3 cycles without a significant loss of efficiency, making it a promising material for the study and application of wastewater treatment. Nanoscale Advances 2516-0230 10.1039/d4na00954a urn:nbn:de:kobv:b43-630797 publish 14.05.2025 false true Noelia Rodríguez-Sánchez Biswajit Bhattacharya Franziska Emmerling Carsten Prinz P. Prieto-Laria A.R. Ruiz-Salvador M. Ballesteros eng uncontrolled Metal-Organic Framework (MOF) eng uncontrolled Heterogeneous photo-Fenton eng uncontrolled ZIF-9 eng uncontrolled Methylene Blue Ingenieurwissenschaften und zugeordnete Tätigkeiten Sanitär- und Kommunaltechnik; Umwelttechnik 6 Materialchemie 6.3 Strukturanalytik Umwelt Umwelt-Material-Interaktionen Material Verlagsliteratur Datei für die Öffentlichkeit verfügbar ("Open Access") Wissenschaftliche Artikel der BAM Materialdesign Bundesanstalt für Materialforschung und -prüfung (BAM) https://opus4.kobv.de/opus4-bam/files/63079/d4na00954a (1).pdf