2D/2D phosphorene/BiOI S-scheme heterojunction for subminute photocatalytic water disinfection under real sunlight

Solar disinfection (SODIS), as a point-of-use (POU) water disinfection strategy for controlling waterborne microorganisms, serves millions of residents daily in over 50 low- to middle-income countries lacking basic drinking water services. However, SODIS is time consuming (6-48 h of sunlight exposure) due to its strong dependence on UV photons, which account for only ~4% of the solar energy. Thus, it is desirable to capture additional energy from visible-light photons (~50% of the solar energy) to accelerate the slow kinetics. Here, we use phosphorene nanoflakes (PNs) and BiOI nanosheets (BS) as model materials to construct a heterojunction photocatalyst, illustrating that simultaneously modulating the interfacial interaction and band alignment between the heterojunction components can achieve a dual optimization of the kinetic and thermodynamic constraints in photo-induced charge carriers, effectively enhancing the utilization of visible-spectrum energy for microbial inactivation. Notably, a subminute photocatalytic water disinfection performance is demonstrated by the PNs/BS heterojunction, completely inactivating 7 log of E. coli within 45 s under real sunlight. This results in a first-order disinfection rate ~221 times greater than that of commercial P25 TiO₂. This work provides insights into the design of potent antimicrobial photocatalysts for POU water disinfection applications.