BACKGROUNDIron (Fe)(3+) has much a smaller ion radius than cerium (Ce)(4+) but praseodymium (Pr) ions have a similar radius to Ce ions with the same valence. Hence, it is interesting to tune the structural properties, including lattice deformation, band gap and oxygen vacancy (O-v), of CeO2 by Pr and Fe codoping for enhanced visible-light catalytic activity. RESULTSA series of Ce1-x-yPrxFeyO2-sigma (x=0 approximate to 0.012, y=0.003 approximate to 0.031) nanoparticles were prepared by a simple one-step sol-gel method. The structural properties of CeO2, including crystal deformation (cell lattice from 5.4069 to 5.4195), band gap (from 2.20 to 2.93), oxygen vacancies (O-v from 0.15% to 9.03%), and peroxide species (O-2(2-) from 0.37% to 1.09%) can be finely tuned by Pr and Fe codoping. Among ten samples, Ce0.982Pr0.003Fe0.015O2-sigma with proper structural properties showed the highest photocatalytic activity towards the degradation of acid orange 7. The first reaction rate constant reaches 0.0687min(-1), 9.3 and 7.7 times that of Ce0.994Pr0.006O2-sigma and Ce0.985Fe0.015O2-sigma, respectively. The mechanism was found to involve OH , O- 2(-) and photogenerated holes. CONCLUSIONThe structural properties of CeO2 can be finely and easily tuned by Pr and Fe codoping. Thus, the photocatalytic activity of CeO2 under visible light irradiation was boosted. (c) 2019 Society of Chemical Industry