Enhanced photoelectrocatalytic performance for degradation of dimethyl phthalate over well-designed 3D hierarchical TiO2/Ti photoelectrode coupled dual heterojunctions

A novel A/R-TiO2 NSs/NRs photoelectrode was constructed through electrodeposition of anatase TiO2 nanosheets (A-TiO2 NSs) with highly exposed {001} facet onto the 1D upright rutile TiO2 nanorods (R-TiO2 NRs). At first, A/R-TiO2 NSs/NRs exhibited enhanced adsorption of dimethyl phthalate (DMP) due to the specific recognition between Lewis acid sites of {001} facet and Lewis basic DMP. NH3-TPD and Py-IR revealed that the Lewis acidity on the {001} facet of A-TiO2 NSs was much stronger than that of R-TiO2 NRs, demonstrating superior adsorption capacity to DMP. DFT theoretical calculations coupled with in-situ ATR-FTIR spectra were performed to investigate the binding adsorption behavior of DMP on A/R-TiO2 NSs/NRs. Secondly, the rapid separation of excited charges and strong oxidation of h+ were achieved by the synergistic effect of dual heterojunctions (A/R "phase heterojunction" and {111}/{110} "facet heterojunction"). The A/R-TiO2 NSs/NRs exhibited 100% degradation efficiency for the target pollutant DMP within 3 h, whose rate constant (k) was 18.02 × 10-3 min-1, 2.16 times that of pure R-TiO2 NRs. In real wastewater application, A/R-TiO2 NSs/NRs achieved 93.8% elimination of DMP during 4 h and preserved excellent stability after 5 cycles, promising a wide-range of applications in water environment remediation.