Bio-electrochemical　systems　(BESs)　have　attracted　wide　attention　in　the　field　of　wastewater　treatment　owing　to　their　fast　electron　transfer　rate　and　high　performance.　Unfortunately,　the　low　electro-chemical　activity　of　carbonaceous　materials　commonly　used　in　BESs　remains　a　bottleneck　for　their　practical　applications.　Especially,　for　refractory　pollutants　remediation,　the　efficiency　is　largely　limited　by　the　cathode　property　in　term　of　(bio)-electrochemical　reduction　of　highly　oxidized　functional　groups.　Herein,　a　reduced　graphene　oxide　(rGO)　and　polyaniline　(PANI)　modified　electrode　was　fabricated　via　two-step　electro-deposition　using　carbon　brush　as　raw　material.　Benefiting　from　the　modified　graphene　sheets　and　PANI　nanoparticles,　the　rGO/PANI　electrode　shows　highly　conductive　network　with　the　electro-active　surface　area　increased　by　12　times　(0.013　mF　cm−2)　and　the　charge　transfer　resistance　decreased　by　92%　(0.23Ω)　comparing　with　the　unmodified　one.　Most　importantly,　the　rGO/PANI　electrode　used　as　abiotic　cathode　achieves　highly　efficient　azo　dye　removal　from　wastewater.　The　highest　decolorization　efficiency　reaches　96　±　0.03%　within　24　h　and　the　maximum　decolorization　rate　is　as　high　as　20.9　±　1.45　g　h−1·m−3.　The　features　of　improved　electro-chemical　activity　and　enhanced　pollutant　removal　efficiency　provide　a　new　insight　toward　development　of　high　performance　BESs　via　electrode　modification　for　practical　application.　©　2023　Elsevier　Inc.