The phenomenon of color-change was first observed in the simple physical mixed Ag3PO4/TiO2 compounds in dark, called "self-corrosion". The difference between self-corrosion and photo-corrosion was clarified. It is found that the chemical environment of Ag is altered in Ag3PO4/TiO2 compounds compared with that in bare Ag3PO4. Furthermore, the change in self-corrosion and its impact on photocatalytic activity were investigated. It is found that under ultraviolet (UV) light irradiation the advantage over bare Ag3PO4 is still maintained in the self-corrosion Ag3PO4/TiO2 compounds due to the similar adsorption capacity. Meanwhile, the photocatalytic activity of self-corrosion Ag3PO4/TiO2 under visible light irradiation is lower than that of fresh Ag3PO4/TiO2 due to the decrease of Ag3PO4. In addition, the identification of oxidative degradation intermediates in the solution was conducted by mass spectra (MS) for the explanation of the degradation mechanism. (C) 2014 Elsevier B.V. All rights reserved.