B-doped, B-N co-doped and B-N-F tri-doped TiO2 catalysts were prepared via a sol-gel method using H3BO3, NH4Cl and NH4F as B, N and N-F dopant precursors, respectively. N-doped, N-F co-doped and a pure TiO2 (undoped) samples were also prepared by the same method as blank samples, for comparison. The catalysts were evaluated for the simultaneous photocatalytic reduction of Cr(VI) and oxidation of benzoic acid (BA). XRD analysis shows the formation of pure TiO2 anatase phase in all cases, with crystallite size varying from 10.1 nm to 14.6 nm for all doped samples. UV-vis DRS spectra show narrowing of the band gap (E-g) for all doped samples, compared to the undoped TiO2. Concomitant presence of N and F ions i.e. in N-F co-doped and B-N-F tri-doped TiO2 catalysts, causes the most pronounced decrease of Eg while B-N co-doped and B-N-F tri-doped TiO2 have lower E-g values than mono B-doped but higher than N-doped and N-F co-doped TiO2. B and N doping also causes an increase of specific surface area and a decrease in mean pore diameter. Electron Paramagnetic Resonance (EPR) spectroscopy was employed for a detailed investigation of the structure and photoexcited species formed in these catalysts. The EPR data show that N-doping forms N-b(center dot) photoexcited species which react as holes, Ti4+-O- oxygen vacancies (OVs) and Ti3+ lattice and surface defects. B-doping enhances the formation of Ti4+-O- oxygen vacancies and the quantities of (O2H)-O-center dot and (OH)-O-center dot radicals. In B-doped and B-N co-doped samples, boron causes the most prominent induction of Ti3+ lattice centers. Boron in interstitial sites, with oxygen atoms [BO3] behaves as a three-electron donor leading to the formation of B3+ and reduction of Ti4+ to Ti3+. Under UV-vis irradiation, Cr(VI) reduction followed the trend: TB1>TBN1>TBNF1>TNF1>TN1>undoped TiO2; while benzoic acid (BA) oxidation trend was: TB1>TBNFI>TBN1>TNFI>TNI>undoped TiO2. Cr(VI) reduction and BA oxidation rates are in agreement with EPR-detected Ti4+-O- oxygen vacancies and (O2H)-O-center dot, (OH)-O-center dot photoexcited radicals, respectively. (C) 2015 Elsevier B.V. All rights reserved.