▎ 摘　　要

Microbial electrochemical system (MES) for enhancing methane production has gained significant interest during the recent years, but the practical applications of MES are still far away due to several limitations such as low efficiency of cathodic electrochemical kinetics. In this study, novel porous reduced-graphene oxide/hollow titania (rGO/TiO2) was successfully synthesized to be used as cathode catalyst for promoting electrochemical reduction of CO2 to methane. The MES operation with rGO/TiO2 catalyst exhibited 15.4% higher methane yield (0.383 +/- 0.01 LCH4/gCOD) and 13.4% higher production rate (152.38 mL/L.d) compared to control MES with bare carbon cloth cathode. The MES-rGO/ TiO2 produced around 33% higher in total Coulomb at 3837.9 +/- 351.5C compared to the pristine cathode at 2887.92 +/- 254.6C. Substrate degradation and volatile fatty acids conversion were significantly improved in the presence of rGO/TiO2 catalyst. By using cyclic voltammetry and electrochemical impedance spectroscopy analysis, rGO/TiO2 was proved to ease the electron transfer efficiency of working cathode for the conversion of electron to methane. The results suggest that porous rGO/TiO2 can be a promising cathode catalyst to upgrade the performance of a scalable methane-producing MES-AD system. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.