Selective Photoelectrocatalytic Degradation of Recalcitrant Contaminant Driven by an n-P Heterojunction Nanoelectrode with Molecular Recognition Ability

With in situ molecular imprinting technique, a novel nanoelectrode (MI, n-P)-TiO2 with n-P heterojunction and molecular recognition ability was fabricated by liquid phase deposition at low temperature. Using bisphenol A (BPA) as template, the spindle-like TiO2 particles 40-80 nm in size compactly grew on the boron-doped diamond (BDD) substrate. Several spectroscopy measurements demonstrate that the BPA molecules were successfully imprinted on the TiO2 matrix and numerous specific recognition sites to template were formed after calcination. The transient photocurrent response experiments have confirmed that the (MI, n-P)TiO2 nanoelectrode displays outstanding photoelectrocatalytic (PEC) activity and selectivity. The (MI, n-P)-TiO2 is further employed in degrading the mixture containing BPA and interference 2-naphthol (2-NP). After 2 h, BPA removal reaches 97%, and corresponding kinetic constant is 1.76h(-1), which is 4.6 times that of 2-NP removal even if 2-NP is much more concentrated. On the electrode without molecular imprint, the removal rate constants of BPA and 2-NP approximately equal, only about 0.5 h(-1). The results indicate that selective PEC oxidation can be realized readily on the (MI, n-P)-TiO2 nanoelectrode due to the synergetic effects including strong recognition adsorption, formation of n-P heteojunction, and external electrostatic field. The effect of formation of n-P heterojunction on the enhanced PEC performances is also discussed.