In-situ synthesis of {111}TiO2/Ti photoelectrode to boost efficient removal of dimethyl phthalate based on a bi-functional interface

We report a novel strategy for preferentially removing dimethyl phthalate (DMP) over rutile {111}TiO/Ti photoelectrode. One-dimensional ordered TiO nanorod arrays with highly-exposed {111} facet on top were in situ grown on Ti mesh via vapor-phase hydrothermal method. {111}TiO/Ti provided a bi-functional interface with a combination of high reaction activity and Lewis acid sites. The photoelectrocatalytic degradation results revealed that {111}TiO/Ti exhibited the highest removal enhancement towards DMP compared with non-target bisphenol A (BPA) and atrazine (ATZ) in both single pollutant and co-existed systems. The factor F was defined to quantitatively analyze the removal enhancement, which were as high as 12.81 and 11.06 towards DMP in the above two systems, respectively. In addition, {111}TiO/Ti also presented an outstanding anti-interference ability when DMP was presented with 10-fold concentration of non-target pollutants. The specific PEC removal of DMP on {111}TiO/Ti photoelectrode was investigated in detail. In situ ATR-FTIR spectroscopy results indicated that the {111} facet displayed stronger Lewis acidity in comparison with TiO/Ti, promoting characteristic adsorption towards target DMP molecule (Lewis base site). DFT results further explored the favorable adsorption configuration of DMP on {111} facet. The time-resolved photoluminescence decay spectra (TRPL) and electron paramagnetic resonance (EPR) spectra confirmed the highly-exposed {111} facet possessed a significant photo-generated holes accumulation. The quenching experiments indicated that •OH was the major active specie in the PEC degradation of DMP. The possible degradation pathways of DMP were proposed by deeply analyzing intermediates. {111}TiO/Ti exhibited excellent stability in recycling experiments, which would have wide applications in practical treatment.