The　global　need　for　clean　water　and　sanitation　drives　the　development　of　eco-friendly　and　efficient　water　treatment　technologies　to　combat　biological　pollution　from　pathogens.　In　this　study,　a　novel　heterojunction　photocatalyst　was　synthesized　by　incorporating　ZnIn2S4　into　covalent　organic　frameworks　(COFs)　to　enable　environmentally　friendly　hydrogen　peroxide　(H2O2)　photosynthesis　and　explore　its　potential　for　in　situ　disinfection.　The　ZnIn2S4/COF　photocatalyst　achieved　remarkable　H2O2　yields　of　1325　mu　mol　center　dot　g-(1)center　dot　h-(1),　surpassing　pristine　COF　and　ZnIn2S4　by　factors　of　3.12　and　16.2,　respectively.　The　produced　H2O2　was　efficiently　activated　into　hydroxyl　radicals　(OH)　through　reaction　with　Fe(II),　enabling　rapid　sterilization　via　a　photocatalysis-self-Fenton　system.　Mechanistic　insights,　supported　by　physicochemical　characterizations　and　theoretical　calculations,　highlighted　the　role　of　the　internal　electric　field　(IEF)　in　enhancing　carrier　separation　and　transfer,　thereby　boosting　photosynthesis　efficiency.　This　work　presents　a　sustainable　approach　to　H2O2　photosynthesis　and　activation　for　disinfection,　offering　a　promising　solution　to　global　water　treatment　challenges.