Photoactivity of Fe and Zn-doped TiO2 in phenol degradation under visible light Panadda Yodsomnuk, Kanya Junjeam and Mutsee Termtanun MATEC Web Conf., 192 (2018) 03047 Published online: 14 August 2018 DOI: 10.1051/matecconf/201819203047