Silver(I)‐Based Complexes Used as High‐Performance Photocatalysts for the Degradation of Organic Dyes in Water

Abstract

Coordination compounds have been used as efficient photocatalysts for the degradation of pollutive organic dyes due to their semiconductive nature and diverse structures that may be adjusted by the central metals and ligands. Herein we prepared N′,N′‐2,2‐tetrakis(diphenylphosphanylmethyl)thiocarbohydrazide (tpptch) and utilized it to react with AgX (X = Br, I, CN) in different solvent systems. These reactions afforded two dicationic tetranuclear complexes {[Ag4X2(tpptch)2]X2 (1: X = Br; 2: X = I)}, one 1D coordination polymer [Ag2I2(tpptch)]n (3) and one neutral tetranuclear complex [Ag4(CN)2(dptpptch)2] (4, dptpptch is the anion of deprotonated tpptch after an enolization). In 1–4, the S atom of the C=S group binds at one AgI atom in 1 or 2, or remains uncoordinated in 3, or connects with two AgI atoms after transforming into the C–S– end in 4. The catalytic activities of these compounds toward the photodegradation of nine organic dyes under UV irradiation were examined, among which 3 showed the best performance. Their anodic photocurrent responses and HOMO–LUMO energy gaps derived from density functional theory (DFT) calculations correlated well with the photocatalytic activities. The different bindings of the S end of tpptch and dptpptch ligands with AgI centers in 2–4 may be contributed to the discrepancy in their catalytic activities. The results provide a ready route to design and prepare highly stable and efficient photocatalysts for treating dye‐polluted water.