Environmental stability and cytotoxicity of layered black phosphorus modified with Polyvinylpyrrolidone and Zeolitic Imidazolate Framework-67

Layered black phosphorus (LBP) is regarded as a promising two-dimensional nanomaterial in various application fields. As bare LBP is unstable in humid environment , many modification methods have been developed recently. However, environmental risks of modified LBP nanomaterials are largely unknown. Herein, by sonication and in-situ surface-confined synthesis, polyvinylpyrrolidone (PVP) coated LBP (LBP/PVP), and zeolitic imidazolate framework-67 (ZIF-67) modified LBP (LBP/PVP-ZIF-67) nanomaterials were synthesized. Environmental stability and toxicity of the modified nanomaterials were compared with bare LBP. Results show that LBP/PVP-ZIF-67 exhibits excellent photothermal performance, and higher potential in electrochemical hydrogen evolution than bare LBP or LBP/PVP. Characteristic visible light absorbance at 593 nm was introduced into the nanomaterial by ZIF-67. LBP/PVP has stability in aqueous environment or cytotoxicity similar to LBP. LBP/PVP-ZIF-67 is completely stable in water within 120 h, in contrast to over 30% degradation of LBP or LBP/PVP. More than 50% of LBP in the LBP/PVP-ZIF-67 can degrade to dissolvable phosphorus in oxygenated water after 17 days, indicating the nanomaterial will not be persistent in the environment. Moreover, modification with ZIF-67 can reduce cytotoxicity of LBP. Therefore, this study develops a safe strategy to modify LBP and provides basic information for ecological risk assessment of LBP based materials.