Viologen-Directed Silver-Thiocyanate-Based Photocatalyst for Rhodamine B Degradation in Artificial Seawater

Photocatalytic degradation is a leading technology for complete mineralization of organic dyes in the ocean. In this work, a new viologen-bearing silver-thiocyanate-based photocatalyst, i.e., {(i-PrV)[Ag₂(SCN)₄]} (i-PrV²⁺ = isopropyl viologen) has been synthesized and structurally determined, with results showing that it can exhibit excellent degradation performance on rhodamine B (RhB) in artificial seawater. The planar i-PrV²⁺ dications are confined in the free voids of the [Ag₂(SCN)₄]² layer with a two-dimensional (6,3) mesh, and strong C-H···S hydrogen bonds contribute to its structural stabilization. This photocatalyst was further characterized by powder X-ray diffraction (PXRD), UV-Vis, fluorescence, and photo/electrical responsive measurements, pointing to its application in visible-light-driven catalysis. Interestingly, using this photocatalyst, good photocatalytic degradation performance on rhodamine B in artificial seawater could be observed. The dye pollutant could be degraded with a high degradation ratio of 87.82% in 220 min. This work provides a promising catalyst for organic dye-type ocean pollutant treatments.