Synthesis, characterization of Mo and Mn doped ZnO and their photocatalytic activity for the decolorization of two different chromophoric dyes by Umar, Khalid, Aris, Azmi, Parveen, Tabassum, Jaafar, Jafariah, Abdul Majid, Zaiton, Vijaya Bhaskar Reddy, Ambavaram, Talib, Juhaizah