Quick　recombination　of　photogenerated　electrons　and　holes　in　photocatalytic　process　remains　a　huge　challenge.　And　the　routine　efforts　are　concentrated　on　heterojunction,　metal　decoration　and　surface　defect　strategies.　PbTiO3　as　a　typical　perovskite　ferroelectrics　is　with　a　strong　built-in　electric　field　as　self-junction　caused　by　internal　spontaneous　polarization,　facilitating　the　charge　separation　in　the　photocatalytic　process.　Here,　under　UV　irradiation,　L-shaped　PbTiO3　with　active　(1　1　0)　facet　as　a　photocatalyst　was　applied　to　photo-reduce　graphene　oxide　(GO),　where　a　specific　reduced　graphene　oxide　(rGO)/PbTiO3　composite　was　synthesized　in　presence　of　isopropanol,　a　hole-trapping　agent.　According　to　the　linear　optical　properties,　the　polarizability　of　PbTiO3　is　calculated　to　1.01　×　10−23　cm3　(2.68　times　that　of　P25　(TiO2)),　inducing　the　photo-excited　charge　separation　by　PbTiO3.　Based　on　XPS　characterization,　a　Ti[sbnd]O[sbnd]C　chemical　bond　is　identified　on　the　interface　between　rGO　and　PbTiO3.　The　response　peak　current　for　an　electrochemical　sensor　based　on　rGO/PbTiO3　was　proportional　to　the　concentration　of　pyrrole　(6.6　×　10−9–3.1　×　10−7　M,　R2　=　0.999),　and　an　extremely　low　limit　reaches　to　2.38　×　10−9　M.　In　addition,　polypyrrole　during　the　pyrrole　detection　was　realized　by　the　multi-cycle　oxidation　process.　And　also,　the　electrochemical　detection　has　been　successfully　applied　for　the　pyrrole　quantification　in　real　samples.　©　2019　Elsevier　Inc.