Developing　efficient　artificial　photocatalysts　for　the　biomimetic　photocatalytic　production　of　molecular　materials,　including　medicines　and　clean　energy　carriers,　remains　a　fundamentally　and　technologically　essential　challenge.　Hydrogen　peroxide　is　widely　used　in　chemical　synthesis,　medical　disinfection,　and　clean　energy.　However,　the　current　industrial　production,　predominantly　by　anthraquinone　oxidation,　suffers　from　hefty　energy　penalties　and　toxic　byproducts.　Herein,　we　report　the　efficient　photocatalytic　production　of　hydrogen　peroxide　by　protonation-induced　dispersible　porous　polymers　with　good　charge-carrier　transport　properties.　Significant　photocatalytic　hydrogen　peroxide　generation　occurs　under　ambient　conditions　at　an　unprecedented　rate　of　23.7　mmol　g-1　h-1　and　an　apparent　quantum　efficiency　of　11.3%　at　450　nm.　Combined　simulations　and　spectroscopies　indicate　that　sub-picosecond　ultrafast　electron　＂localization＂　from　both　free　carriers　and　exciton　states　at　the　catalytic　reaction　centers　underlie　the　remarkable　photocatalytic　performance　of　the　dispersible　porous　polymers.　Current　industrial　production　of　hydrogen　peroxide　suffers　from　hefty　energy　penalties　and　toxic　byproducts.　Here,　the　authors　report　efficient　photocatalytic　production　of　hydrogen　peroxide　by　protonation-induced　dispersible　porous　polymers　with　good　charge-carrier　transport　properties.