Preparation, characterization of N-I co-doped TiO2 and catalytic performance toward simultaneous Cr(VI) reduction and benzoic acid oxidation

- N-I co-doped TiO2 catalysts were characterized by EPR spectroscopy.
- Nb, O2− radicals and TiO4+-O− holes, Ti3+ surface defects were detected.
- The reduction efficiency of N-I co-doped TiO2 depends on Nb species quantity and Eg values.
- TNI5 (Ti:N/I molar ratio of 1:5) showed higher photocatalytic reduction of Cr(VI).
- TiO4+-O− holes are inversely correlated with benzoic acid oxidation rates.