Photoluminescent materials for highly toxic metals sensing: From downconversion to upconversion

Highly toxic metals (Hg²⁺, Pb²⁺, Cd²⁺ and Cr⁶⁺) in environment waters greatly threaten the health of human beings and ecosystem. Photoluminescent sensing has been considered as an effective technology for metals monitoring in environment medium. In this paper, photoluminescent materials for the sensing of highly toxic metal ions (HTMs) were reviewed. These materials were categorized as downconversion materials and upconversion nanomaterials, according to the mechanism of photon conversion. Downconversion materials generally include organic probes, quantum dots, and Au or Ag nanomaterials. Together with upconversion nanomaterials, they are introduced in terms of textures and modification methods. The working mechanisms were introduced emphatically as well as their advantages and disadvantages for HTMs sensing. In Section 4, the conclusion and perspectives of photoluminescent sensing materials are summarized, and it is expected that this review will be helpful for the understanding and fundamental studies of photoluminescent materials for the detection of HTMs.