Metal-Free Organic Optoelectronic Molecule as a Highly Efficient Photocatalyst for the Degradation of Organic Pollutants

With the increasing consumption of natural resources, photocatalysis converting solar energy to chemical energy has attracted extensive attention of researchers owing to the advantages of developing energy-saving and environmentally benign processes. In this work, a facile and simple method was developed to synthesize a metal-free organic optoelectronic molecule (denoted as DPPRD), which is composed of a central diketopyrrolopyrrole moiety and two terminal units of a rhodanine (RD) moiety. This is a first green strategy toward the synthesis of DPPRD. Because of good thermal stability, narrow band gap, and excellent visible light absorption of solar spectrum, DPPRD exhibited to be an efficient and chemically stable photocatalyst for visible light degradation of organic pollutants such as bisphenol A (BPA) and methyl orange (MO) in aqueous solution. The control experiments with different types of radical scavengers implied that the hole (h+) and hydroxyl radicals (•OH) were the key reactive species during the photodegradation processes. The photodegradation pathways of BPA and MO were thus proposed based on the identified intermediates. This improved method for DPPRD synthesis is expected to widen its applications to industrial production, whereas its excellent visible light photocatalytic activity would be utilized potentially in the field of environmental and industrial applications.