Spin polarization engineering on SnS2 for improving photocatalytic disinfection

Abstract

With the emergence and massive spread of antibiotic-resistant bacteria, it is urgent to develop new bactericidal technologies. Photocatalytic sterilization is a technique that uses solar energy to produce reactive oxygen species to kill pathogenic bacteria, and ROS effects depends on the charge separation characteristics of photocatalysts, so the development of strategies to promote charge separation is crucial. Here, we use the strategy of introducing sulfur vacancy on SnS2, effectively improving the separation of photogenerated charge. The femtosecond transient absorption results confirm that the charge lifetime of SnS2 (Sv-SnS2) after the introduction of the sulfur vacancy is 13.33 times that of pristine SnS2. The DFT theoretical results confirm that sulfur vacancy causes spin polarization. It is easier to separate when the spin direction of the electrons and holes changes. In addition, the sulfur vacancy also expands the light absorption range and exposes the surface catalytic site. These phenomena lead to a higher ROS yield of Sv-SnS2 (confirmed by electron paramagnetic resonance results). Thus, Sv-SnS2 killed 99.99 % of E. coli and MRSA within 40 min under visible-light illumination. This efficient bactericidal performance can be attributed to improved photogenerated charge separation. This study confirms the effectiveness of sulfur vacancy strategy to improve charge separation and extend charge life, and applies it to the killing of antibiotic resistant bacteria, providing a new idea for the killing of resistant bacteria.