Size-Controlled microporous SiO2 coated TiO2 nanotube arrays for preferential photoelectrocatalytic oxidation of highly toxic PAEs

Abstract

Elimination of toxic environmental endocrine disruptors from wastewater systems is of great significance and still remains a grand challenge. A microporous SiO2 coated TiO2 nanotube arrays photoelectrocatalyst is prepared with controllable thickness and pore size to selectively oxidize highly toxic phthalate esters (PAEs) from complex coexisting systems. With the construction of SiO2 layer, the specific surface area increased from 105.34 m2 g-1 to 237.28 m2 g-1 compared to substrate electrode. Further confirmed by in situ IR spectroelectrochemical measurements, this system exhibited higher affinity towards target PAEs molecules, where the adsorption strength of PAEs was 3.23-fold that on the substrate electrode, while that of H2O only improved by 52%. More importantly, our designed system displayed excellent preferential removal towards PAEs in the coexistence of 10-fold concentrated natural organic matters. Meanwhile, PAEs can only be 12.6% oxidized on the substrate electrode at the same coexisting system. A novel photoelectrocatalysts is proposed employing size filtration technology to realize both effective and selective elimination of defined and highly toxic contaminations in complex coexisting systems.