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-electrocatalytic (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 pi 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.