Amino-terminated polydimethylsiloxane modified porphyrin for efficiently biphasic photosynthesis of H₂O₂

Hydrogen peroxide (H₂O₂) attracts widespread attention as a clean and sustainable oxidant. Nevertheless, porphyrin-based photocatalysts generally exhibit low H₂O₂ concentration in aqueous systems because the generated H₂O₂ does not accumulate effectively and is difficult to separate from the water. Here, we report an amino-terminated polydimethylsiloxane (NH₂-PDMS) modified supramolecular tetrakis(4-carboxyphenyl) porphyrin (SA-TCPP) for effectively photocatalytic H₂O₂ production in a water/n-decane biphasic system. We illustrate that the formation of amide bonds (–CO–NH–) between NH₂-PDMS and SA-TCPP regulates the catalyst’s surface from hydrophilic to hydrophobic, enabling its uniform dispersion in the nonpolar (n-decane) organic phase. We further demonstrate that this spatial distribution effectively separates the NH₂-PDMS@SA-TCPP catalyst from the generated H₂O₂, allowing H₂O₂ to accumulate in the aqueous phase and reducing its decomposition. The NH₂-PDMS@SA-TCPP catalyst delivers an H₂O₂ generation rate of 10.5 mM·h⁻¹ and an apparent quantum efficiency as high as 16.02% at 420 nm. Additionally, in a long-term run, the accumulation of H₂O₂ with concentration is found to reach ca. 0.65 wt.%, close to the commercial level (1 wt.%–3 wt.%). This biphasic design provides a simple approach for efficient, stable, and sustainable H₂O₂ production.