The　carrier　transfer　mechanism　of　S-scheme　heterojunctions　has　been　extensively　explored,　yet　their　impact　on　light　absorption　performance　remains　ambiguous.　In　this　work,　a　finely　designed　S-scheme　heterojunction　was　developed　by　coupling　oxidation　photocatalyst　a　specific　covalent　organic　framework　(COF)-TaTp,　and　reduction　photocatalyst　SnS2　(SS)　for　in-situ　H2O2　photo-production　and　sterilization.　The　optimized　10%　SS/TaTp　achieved　a　3.45-　and　16.87-fold　enhancement　in　H2O2　generation　than　pure　TaTp　and　SS,　respectively,　with　significant　improvements　under　visible　and　near-infrared　(NIR)　light.　In-situ　XPS,　EPR,　and　Kelvin　probe　force　microscopy　(KPFM)　verified　the　S-scheme　charge　transfer　mechanism,　underscoring　accelerated　photo-induced　electrons　migration　and　strengthened　redox　capacity.　The　internal　electric　field　of　10%　SS/TaTp　was　calculated　to　be　2.14　and　4.63　times　stronger　than　TaTp　and　SS.　Intriguingly,　the　electron　localization　function　and　partial　density　of　states　analyses　revealed　that　the　interfacial　C-N-S　covalent　bonds　finely　tuned　the　energy　band　structure　and　generated　hybrid　energy　levels　in　the　heterojunction,　thus　improving　light　harvesting　and　catalytic　performance　in　both　visible-light　and　NIR　region.　This　work　highlights　the　role　of　interfacial　covalent　interactions　in　tuning　energy　levels　in　COF-based　S-scheme　photocatalysts.　©　2025　Elsevier　B.V.