Preparation, structural analysis, efficient photocatalytic degradation mechanism and pathway for p-nitrophenol of Ag-deposited Co-coordination polymer composites

Abstract

This study addressed the problem of photogenerated charge complexation in coordination polymers (CPs), a considerable barrier to stable, high-performance photocatalysts, by hydrothermally preparing a novel cobalt coordination polymer, [Co(DDB)0.5(PTP)(DMA) (H2O)2]·H2O (Co-CP) using the mixed ligands 1,4-di(3,5-dicarboylphenoxy) benzene (H4DDB) and 4′-(4′′-pyridyl)-2,4′,6′,4′′-terpyridine (PTP). Theoretical calculations have demonstrated that the metal-to-ligand charge transfer (MLCT) in Co-CP is crucial in enhancing charge separation efficiency. Additionally, a silver-deposited composite (Ag@Co-CP) was synthesized through photoreduction. With 1.65wt% Ag, the Ag@Co-CP-2 composites exhibited optimal photocatalytic degradation of various organic pollutants, including nitroaromatic, rhodamine B, methylene blue, basic magenta, and methyl orange. Using charge-coupled devices, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, density functional theory, electron spin resonance measurements, and liquid chromatography-mass spectrometry, we extensively examined the morphology, structure, and photoelectric properties of the developed materials. Our exploration of the structural-activity relationship was supported by results from these structural and optoelectronic analyses. Free radical capture tests and analyses of electron spin resonance led us to pinpoint ·O2−, h+, and ·OH as significant contributors to the reaction system. Finally, we outlined the degradation process, reaction mechanism, and potential pathways. This study contributes to the critical task of designing interfaces between noble metals and semiconductors for improved photocatalytic performance.