In　this　work,　the　n-type　TiO2　nanotube　film　was　modified　successfully　by　n-type　MnIn2S4　nanoparticles　with　one-step　hydrothermal　method,　and　a　novel　MnIn2S4/TiO2　heterojunction　material　with　excellent　photo-electrochemical　properties　was　constructed　firstly.　Owing　to　the　modification,　the　light　response　range　of　MnIn2S4/TiO2　nanocomposites　was　extended　to　the　visible　light　region.　Benefiting　from　the　presence　of　type　II　n-n　heterojunction　with　built-in　electric　field　effects　in　the　nanocomposites,　the　photogenerated　carriers　recombination　rate　decreased　significantly.　In　addition,　the　photocathodic　protection　effects　of　MnIn2S4/　TiO2　(MIS/T)　photoanodes　on　Q235　carbon　steel　(Q235　CS)　immersed　in　simulated　concrete　pore　solution　containing　chloride　were　investigated.　Under　visible　light　irradiation,　the　cathodic　protection　current　density　of　MIS/T-2　photoanode　was　found　to　be　more　than　30　mu　A/cm2　and　over　10　times　that　of　T　photo-anode.　The　MIS/T-2　photoanode　has　good　long-term　photochemical　stability　and　maintains　excellent　photocathodic　protection　effect　on　Q235　CS　(OCP　value　are　about　-870　mV　(vs.　SCE))　under　visible　light　irradiation.　The　amount　of　MnIn2S4　nanoparticles　deposited　on　the　TiO2　film　could　affect　the　photoelec-trochemical　properties　of　MnIn2S4/TiO2　n-n　heterojunctions　and　an　appropriate　number　of　the　nano-particles,　corresponding　to　the　best　cathodic　protection　performance　was　revealed.(c)　2023　Elsevier　B.V.　All　rights　reserved.