A solar cell with an ultra-reactive confined microinterface for high-flux water purification

Advanced oxidation processes represent effective approaches toward water purification, but they are often energy and chemical intensive. Here, we show a solar cell with a highly reactive microinterface for high-flux wastewater treatment with requirements for only water, oxygen, and sunlight. Experiments demonstrate that hydrogen peroxide is produced in a porous cathode via two-electron oxygen reduction and then flows to a porous photoanode surface, where it is instantly activated to hydroxyl radicals (⋅OH) by light and integrated with indigenous ⋅OH generated via one-electron water oxidation. Accordingly, a microscale region (∼150 μm for thickness) with high-density ⋅OH (∼2.5 mM) is successfully constructed but remains spatially constrained on the photoanode surface. Refractory pollutants (such as norfloxacin) pass through this microinterface successively and are degraded rapidly (>99% in ∼0.6-s retention time) due to violent collision between ⋅OH and targets, even after 360 h of long-term operation. Our findings highlight an innovative catalytic platform design scheme for efficient water purification.