Polyaniline hybridization promotes photo-electro-catalytic removal of organic contaminants over 3D network structure of rGH-PANI/TiO2 hydrogel

Herein, reduced graphene oxide-polyaniline/titanium dioxide composite (rGH-PANI/TiO2) with three-dimensional (3D) network structure was successfully synthesized by a two-step method involving a hybridization process and a water bath approach. The rGH-PANI/TiO2 hydrogels showed excellent performance in the degradation of various organic contaminants. The efficiencies of rGH-PANI/TiO2 hydrogels for photo-electro-catalytic (PEC) removal of phenol was 100% much higher than that of photocatalysis (42%) and electrocatalysis (68%) alone. Meanwhile, the efficiencies of bisphenol A and 2,4-dichlorophenol were 100% after 4.5 and 3.5 h. More important, rGH-PANI/TiO2 hydrogels have excellent mineralization ability for coking wastewater, and the removal rates of total organic carbon (TOC) and chemical oxygen demand (COD) reached 53.1% and 71.9%, respectively. Furthermore, the activities of rGH-PANI/TiO2 for PEC degradation of phenol were also investigated under different conditions, such as phenol concentrations, sodium sulfate (Na2SO4) concentrations, and pH value. The results revealed that rGH-PANI/TiO2 had outstanding PEC performance for the degradation of contaminants. This is because PANI is an excellent material for transporting holes. The large π bonds on graphene promote the rapid transfer of electrons. The addition of PANI and rGH promotes the separation of electron-hole pairs, and the degradation efficiencies of contaminants were improved. Therefore, the reported rGH-PANI/TiO2 composites have excellent potential to purify industrially generated wastewater thanks to their outstanding PEC performance.