Construction of p-n heterojunction in nanozymes for enhanced antibiofouling activity in solar evaporation seawater desalination

As a prospective seawater desalination technology, solar evaporation has received widespread attention. However, solar evaporation systems are consistently troubled by biofouling, which not only reduces evaporation performance but also corrupts water quality and leads to secondary pollution. To counteract this unfavorable situation, nanozymes are a desirable option because they can produce reactive oxygen species (ROS) and efficiently eliminate microorganisms. In this context, a nanozyme, namely CoS/MoS2, is synthesized. Compared with MoS2, CoS/MoS2 exhibits more excellent oxidase-mimic activity, as a p-n heterojunction is constructed between p-type CoS and n-type MoS2. A mechanism analysis demonstrates that the p-n heterojunction promotes interfacial charge redistribution and elevates the d-band center position, which enhances O2 adsorption and improves oxidase-mimic activity. CoS/MoS2 also demonstrates perfect photothermal properties. A CoS/MoS2@SA foam was fabricated with CoS/MoS2 and sodium alginate (SA), which shows excellent solar evaporation seawater desalination performance. The foam also exhibits antibiofouling properties and is suitable for long-term water purification. The quality of the evaporated water meets the standards for drinking water. We anticipate that nanozymes with high antibiofouling and photothermal performance will be widely employed in solar evaporation seawater desalination.