A low-cost solar disinfection platform: hydrogel-encapsulated benzyl frameworks for continuous in situ H2O2-driven water treatment.

Decentralized water disinfection in resource-limited regions urgently requires low-cost, solar-driven technologies that avoid chemical dosing and complex infrastructure. Photocatalytic H2O2 generation offers a clean alternative, but practical deployment is hindered by the poor processability, difficult recovery of powdered photocatalysts and high cost. Here, we address these barriers by developing a benzyl-integrated frameworks (BIFs) synthesized exclusively from benzene via a one-step Friedel-Crafts reaction. Despite its minimalist, non-conjugated structure, BIF exhibits broad-spectrum visible-light absorption and efficient H2O2 production (∼3.8 mmol g-1 h-1) via an unconventional interlayer π-π coupling mechanism. To enable continuous-flow operation, we encapsulated hydrophobic BIF into an agar hydrogel using a DMSO-mediated solvent-exchange strategy. The resulting composite hydrogel not only prevents aggregation but also enhances H2O2 production by 1.3-fold through improved mass transfer. When packed into a fixed-bed column, this solar biocidal gel achieves rapid and complete inactivation of E. coli (104 CFU mL-1, typical of treated wastewater) at flow rates up to 52 mL min-1, corresponding to a biocidal efficiency of 1300 CFU min-1 mg-1. With a daily treatment capacity of ∼75 L per gram of BIF, this work provides a practical, scalable, and energy-autonomous platform for solar-driven water disinfection, demonstrating that high performance need not come at the cost of complexity.