Effective decolorizations and mineralizations of organic dyes over a silver germanium oxide photocatalyst under indoor-illumination irradiation

Abstract

A silver germanium oxide, Ag 2GeO 3, was developed as a novel photocatalyst for degradation of organic dyes. The chemical composition of the sample was investigated via the SEM/EDX, ICP-AES, and TG-DTA techniques. The general activity of the material was characterized by testing the photodegradations of typical organic dyes, such as Methylene Blue (one of the heteropolyaromatic dyes), Rhodamine B (one of the xanthene dyes), Fuchsin Acid (one of the sulfonic dyes), and Orange II (one of the azoic dyes). All of these dyes were degraded more than 90% within 25 min under the visible-light irradiation of Xe lamp. Besides, with a commercial white fluorescent lamp as testing light source (light intensity, 61 μW/cm 2), the efficient decolorizations and mineralizations of the organic dyes were achieved over this material: 79% (90%) of the organic carbon in the Methylene Blue (Rhodamine B) solution was photooxidatized to inorganic carbon forms, when these dyes were totally decolorized. The high performance of this material is due to the photophysical properties of the wide-visible-range absorption and response, and the sufficient oxidative potential of the top of the valence band.