Visible light responsive CuS/ protonated g-C3N4 heterostructure for rapid sterilization

[Display omitted] •Heterojunction was constructed by between CuS and protonated g-C3N4 via electrostatic adsorption.•The photothermal property of CuS/PCN increased with the increasing of the content of CuS.•The photocatalytic ability of CuS/PCN was enhanced due to the heterojunction construction.•The CuS/PCN exhibited efficiently bacteria-killing under visible light irradiation for 20 min. As the environment deterioration is becoming more serious, bacterial pollution is threatening the health of human beings. Hence, it is vital to develop rapid and safe sterilization strategy. Herein, CuS/protonated g-C3N4(CuS/PCN) composites were synthesized by simple hydrothermal method and electrostatic adsorption. This heterostructured system exhibited enhanced photocatalytic properties under visible light compared with CuS or g-C3N4 alone, ascribing to the rapid separation of photogenerated electron-hole pairs. Meanwhile, the obvious photothermal effects of CuS/PCN were achieved and the temperature increased with the increased amount of CuS in the composites due to the more light absorption. However, when the CuS content is more than 10 %, photocurrent density is decreased with increasing the amount of CuS, indicating the increased recombination of photogenerated electron-hole pairs. When the CuS content is 20 %, the composite can perform the optimized synergistic effects of both photothermal action and photocatalysis under light irradiation for 20 min. The corresponding bacteria-killing efficiency against Staphylococcus aureus and Escherichia coli is 98.23 % and 99.16 %, respectively. The underlying mechanism is that the bacterial membrane can be weakened by reactive oxygen species and bacterial activities are inhibited by hyperthermia. This CuS/PCN heterojunction is promising for environmental disinfection including water and public facilities sterilization.