Carbon quantum dots derived from waste acorn cups and its application as an ultraviolet absorbent for polyvinyl alcohol film

One-Step Hydrothermal Synthesis of Nitrogen-Doped Carbonized Polymer Dots with Full-Band Absorption for Skin Protection

“…Carbon polymer dots (CPDs) are a typical zero-dimensional carbon-based nanomaterial and are widely used in catalysis, , biosensing, , and anti-counterfeiting − due to their small size, simple preparation, coordinated luminescence, water solubility, excellent chemical inertness, and high biocompatibility. − CPDs with excellent UV absorption properties have also been developed. Huang et al prepared UVA-absorbing CPDs with blue fluorescence using cotton fibers as the carbon precursor and urea as the dopant, which were combined with TiO 2 for photovoltaic window applications; Xu et al synthesized UVB-absorbing CPDs from acorn cups for application in the UV conversion system of the PVA film having potential significance; S. Patil et al synthesized CPDs from discarded tea pomace combined with PVA, which can achieve a UVB and UVC blocking rate of 100% and a UVA blocking rate of 60% as a sustainable energy source for food packaging applications. Hess et al used citric acid and PEI to synthesize carbon dots in the UVA band.…”

Controllable Synthesis of Carbon Dots@CaCO3 Composites: Tunable Morphology, UV Absorption Properties, and Application as an Ultraviolet Absorber

“…On the solar spectrum, the energy of ultraviolet light (UV) is higher than that of visible light. It can be divided into UVA (400–320 nm), UVB (320–280 nm), UVC (280–100 nm), and EUV (100–10 nm). , Excessive UVA and UVB radiations elicit serious damage to plants and animals, affect biological reproduction, lead to climate and ecological changes, and particularly result in significant damage to human health. , Large amounts of UV radiation can also reduce the reproductive capacity of marine organisms, disrupt the mating habits of insects, and damage plants, especially crops, reducing crop yields on Earth by 2/3 and leading to a food crisis …”

“…The films not only blocked the UV region but also re-emitted the absorbed light from UV to the visible region. Xu et al combined chitosan (CS) into CDs using acorn cups (ACs) as carbon point raw materials to synergistically functionalize PVA films as UV absorbers. The UV-blocking ratio of PVA/CS/CDs films reached more than 80%.…”

Synthesis of Carbon Dots with Carbogenic π-Conjugated Domains for Full-Band UV Shielding

“…After decades of development, there have been abundant and commercialized ultraviolet absorbers, which can be divided into chemical absorbers, physical shielding agents, , and natural UV absorbers . However, the majority of the commercial organic UV absorbers such as benzophenone and other aromatic compounds are prohibited or strictly limited to industrial products in contact with the human body or food due to their instability and tendency to produce toxic photoadducts . Moreover, the structure of organic UV absorbers is extremely easily destroyed after a long period of UV radiation, leading to a greatly reduced UV absorption efficiency .…”

“…More importantly, CDs are regarded as the most promising alternative to commercial UV absorber for absorption of UV rays and chemically inert . In the last few years, the usage of CDs as UV absorbers has been increasingly reported; for example, organic molecules such as citric acid are used as a carbon source for the hydrothermal synthesis of CDs for UV shielding. − Biomass carbon dots (CDs) from renewable materials have also been successfully used for UV absorption. ,, However, the reported CDs have relatively low UV shielding rates and narrow-band UV shielding and usually produce absorption only in a single region of UVA or UVB, which may necessitate their use in combination with nano ZnO or organic chemical UV absorbers. , High-efficiency CD ultraviolet absorbers that can absorb over the entire ultraviolet range have rarely been reported thus far. Therefore, it is essential to explore more new UV blocking materials with high stability and outstanding all-waveband UV blocking behavior.…”