The　desired　anticorrosive　effect　of　rebar　through　photocathodic　protection　of　TiO2　is　challenging　due　to　its　wide　bandgap　and　high　recombination　rate　of　photogenerated　carriers.　This　study　demonstrates　that　the　CuInSe2/TiO2　nanocomposites,　which　consist　of　novel　TiO2　nanobowls　and　CuInSe2　nanoparticles,　can　significantly　enhance　the　corrosion-resistant　performance　of　HRB400　steel　rebar.　The　CuInSe2/TiO2　nanocomposite　films,　featuring　an　n-n　heterostructure,　were　fabricated　by　hydrothermally　synthesizing　n-type　CuInSe2　nanoparticles　onto　anodic　oxidation-prepared　n-type　TiO2　nanobowl　films.　Notably,　the　CuInSe2　nanoparticles　significantly　enhanced　the　light　absorption　properties　of　TiO2,　particularly　in　the　visible　light　range.　The　presence　of　heterogeneous　interfaces　in　the　CuInSe2/TiO2　films　effectively　reduced　the　carrier　recombination　rate.　Under　visible　light　irradiation,　the　photocurrent　density　of　CuInSe2/TiO2　photoanode　(CT-5:　17.37　μA/cm2)　was　significantly　higher　compared　to　that　observed　for　the　TiO2　photoanode　(1.05　μA/cm2).　Moreover,　in　a　simulated　concrete　pore　solution　containing　3.5　wt%　NaCl,　the　photocathodic　protection　potential　(OCP　value)　of　HRB400　rebar　coupled　with　CT-5　was　approximately　−820　mV　(vs.　SCE),　which　is　significantly　more　negative　than　that　of　the　−630　mV　observed　for　the　rebar　coupled　with　TiO2.　Therefore,　the　novel　CuInSe2/TiO2　n-n　heterojunction　films　exhibited　remarkable　photocathodic　protection　for　the　HRB400　rebar,　demonstrating　that　the　heterojunction　enhances　the　corrosion　resistance　of　TiO2　for　steel　rebars.　©　2025　Elsevier　B.V.