The investigation of optical and photocatalytic properties in Dy2M2O7 (M= Hf, Zr and Ce) 

A great effort has been done to improve the efficiency of materials for photo-catalytic water splitting application. The most famous catalysis is TiO 2 , but its band gap, exceeds 3.0 eV, doesn’t fit into the visible spectrum. so, to exploit this range of energy, we are looking for other materials having band gap lower that 2.0 eV. The research focused on the enhancement of photo-catalysis by modification of TiO 2 by means of metal loading, metal ion doping, …This paper aims to present a group of compounds Dy 2 M 2 O 7 (with M = Hf, Ce and Zr) which could be an alternative having the same function as TiO 2 . Based on our studies and those reported in the literature, we will discuss in detail the roles and the functional mechanism of the catalysts. The results show that Zr 2 Dy 2 O 7 is the best candidate to be a photo-catalyst: it has a band gap close to 2.2 eV, and a good absorption in visible range compared to the other compound having absorption in UV. The quantum efficiency of Zr 2 Dy 2 O 7 reaches up to 3%, and the limit of conduction band and valence band are localized in potential redox zone. Doping with Cerium gives another energy level which allows to have other optical transitions, improve the absorption and reach the quantum efficiency to 4% in a visible range.