Expanded graphite supported TiO2 composites using polyaniline as the anchor: Improved catalytic performance for the electro-Fenton-like reaction

TiO2 has been widely used as the catalyst to generate •OH in advanced oxidation processes. As a semiconductor, TiO2 was usually combined with carbon materials to improve its weak electrical conductivity. However, the metal-nonmetal interface barrier between TiO2 and carbon materials led to an unstable combination, and consequently remained a key obstacle to enhance the catalytic activity of TiO2. To overcome this barrier, polyaniline (PAN) was introduced onto expanded graphite (EG) as the anchor for TiO2 loading in this study. After PAN uniformly distributed on the surface and intercalated between the layers of EG as the anchor, an evident increasing of flaky TiO2 was observed on the EG, while agglomerated TiO2 decreased. Electrochemical analysis proved that these flaky TiO2 induced a higher electrochemical activity and more active sites towards ORR. Density functional theory (DFT) calculations and morphology analysis confirmed that the PAN played a vital role when loading TiO2 on EG. Especially, PAN anchors were proved to increased oxygen vacancies in TiO2. On the other hand, EG supported TiO2 using PAN as the anchor (EG-PAN-TiO2) possessed the advantage in preparing self-supporting electrode due to the decreasing of agglomerated TiO2. When the EG-PAN-TiO2 self-supporting electrode was used as the cathode to establish an electro-Fenton-like system, it displayed a higher •OH yield, enhanced pollutant degradation efficiency, and improved reusability compared with EG supported TiO2 without PAN anchors. This work provided an attractive strategy to enhance the carbon-TiO2 interaction using PAN as the exogenous anchor, which was prospective to improve the catalytic activity of metal-nonmetal composite catalysts.