Enhanced performance of TiO2/reduced graphene oxide doped by rare-earth ions for degrading phenol in seawater excited by weak visible light

La 3+ - or Yb 3+ -doped TiO 2 supported on the surface of reduced graphene oxide were fabricated by adsorbed-layer nanoreactor synthesis (ANS) coupling with a solvothermal treatment to extend photocatalysis application in the advanced treatment of simulated wastewater with high salt concentration. Results showed that La 3+ or Yb 3+ could distribute in the TiO 2 lattice, only in ANS preparation with graphene oxide as the carrier, to replace Ti 4+ during the solvothermal treatment, thus introducing TiO 2 mixed-crystal and heterojunction structures in the catalysts. La 3+ or Yb 3+ caused lattice distortion structures and anionic vacancies in the TiO 2 lattice. The anionic vacancies (oxygen vacancies) might generate Ti 3+ in catalysts, thus enhancing visible-light response, due to impurity levels introduced by La 3+ or Yb 3+ . As the strong adsorption capability of the catalyst for phenol was not interfered by salt ions in the simulated wastewater, the catalysts could efficiently degrade phenol. The highest removal rate of phenol was approximately 90%.