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 MgIn2S4 onto In2O3 to fabricate MgIn2S4@In2O3 hierarchical tubular heterostructures. Using the model microbes Escherichia coli bacteria, we demonstrate that MgIn2S4@In2O3 can achieve an exceptionally high antimicrobial activity (7 log reduction in viable cells count for 30 min illumination) although MgIn2S4 and In2O3 alone are almost inactive. Owing to the intimate contact between MgIn2S4 and In2O3, MgIn2S4@In2O3 enables efficient photocarrier separation which supports continuous production of copious reactive species (i.e. h+ and O2−) for disinfection. Numerical simulation indicates that photocarriers are spatially well-separated in MgIn2S4@In2O3 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.