Red Phosphorus: An Earth-Abundant Elemental Photocatalyst for “Green” Bacterial Inactivation under Visible Light

Abstract

Earth-abundant red phosphorus was found to exhibit remarkable efficiency to inactivate Escherichia coli K-12 under the full spectrum of visible light and even sunlight. The reactive oxygen species (•OH, •O2(-), H2O2), which were measured and identified to derive mainly from photogenerated electrons in the conduction band using fluorescent probes and scavengers, collectively contributed to the good performance of red phosphorus. Especially, the inactivated-membrane function enzymes were found to be associated with great loss of respiratory and ATP synthesis activity, the kinetics of which paralleled cell death and occurred much earlier than those of cytoplasmic proteins and chromosomal DNA. This indicated that the cell membrane was a vital first target for reactive oxygen species oxidation. The increased permeability of the cell membrane consequently accelerated intracellular protein carboxylation and DNA degradation to cause definite bacterial death. Microscopic analyses further confirmed the cell destruction process starting with the cell envelope and extending to the intracellular components. The red phosphorus still maintained good performance even after recycling through five reaction cycles. This work offers new insight into the exploration and use of an elemental photocatalyst for "green" environmental applications.

Light‐Activated Rapid Disinfection by Accelerated Charge Transfer in Red Phosphorus/ZnO Heterointerface

“…In heterostructures, photoexcited charge carriers are transported not only along the surface of each component, but also at the interface . Notably, the effective transport of photoexcited charge carriers at the heterostructure interface plays a prominent role in improving the photocatalytic activity .…”

“…Elemental phosphorus has three allotropes, white, black, and red P, among which red phosphorus (RP), both amorphous and crystalline, has been applied for photocatalytic H 2 evolution and water splitting under visible light . More importantly, RP is nontoxic, relatively stable, economical, and environmentally friendly . Fibrous RP is a direct bandgap semiconductor with a bandgap of ≈1.5 eV and shows high absorption over the solar spectrum, consequently displaying great potential for light‐driven bacterial inactivation.…”

Two‐dimensional nanomaterials for photocatalytic water disinfection: recent progress and future challenges

“…60 After that, the ultimate target of RSs, the genetic materials of microorganisms, such as nucleic acids and DNA, rapidly decay, resulting in cell death with no regrowth. 10,123 However, in different photocatalytic systems, the dominant active species vary. Actually, photocatalytic disinfection is normally a multi-factor controlled issue that combines the effects of more than one kind of reactive species.…”

The Cytotoxicity of Layered Black Phosphorus

“…White phosphorus hasb een reported to be nearly as toxic as cyanide, with chronic exposure capable of causing an awful condition of bone necrosis. [13,15,16] Surprisingly,f or black phosphorus, no conclusive data pertaining to its toxicityh as yet been established, with only one article mentioning BP to be non-toxic. [14] Red phosphorus, on the other hand, was found to be nontoxic.…”