MgIn2S4@In2O3 hierarchical tubular heterostructures with expedited photocarrier separation for efficient visible-light-driven antimicrobial activity

Semiconductor-based photocatalytic techniques provide a durable and environmentally benign route to disinfect microbes. However, their disinfection activities are often limited by inadequate use of photocarriers (e − and h + ), particularly for narrow bandgap semiconductors. Here, we directly grow narrow bandgap semiconductor MgIn 2 S 4 onto In 2 O 3 to fabricate MgIn 2 S 4 @In 2 O 3 hierarchical tubular heterostructures. Using the model microbes Escherichia coli bacteria, we demonstrate that MgIn 2 S 4 @In 2 O 3 can achieve an exceptionally high antimicrobial activity (7 log reduction in viable cells count for 30 min illumination) although MgIn 2 S 4 and In 2 O 3 alone are almost inactive. Owing to the intimate contact between MgIn 2 S 4 and In 2 O 3 , MgIn 2 S 4 @In 2 O 3 enables efficient photocarrier separation which supports continuous production of copious reactive species ( i.e. h + and O 2 − ) for disinfection. Numerical simulation indicates that photocarriers are spatially well-separated in MgIn 2 S 4 @In 2 O 3 due to the type-II heterojunction formed. These findings signify the possibility to achieve high antimicrobial activity from otherwise almost inactive semiconductors by properly constructing the heterogeneous interfaces.