No abstract

Chitosan is an abundant biopolymer derived from food waste with attractive properties, particularly its high biocompatibility and easy chemical processability. Here, we review the rapidly expanding literature on chitosan‐based porous materials with a focus on the gelation mechanisms, the three‐dimensional multiscale structural control, and the diverse chemical functionality not accessible by other biopolymers. The properties vary widely: from supercritically dried, mesoporous chitosan aerogels to very light, freeze‐dried macroporous scaffolds. Porous chitosan displays impressive performance at the laboratory scale, but the highly (meso)porous nature amplifies not only the beneficial functionality of chitosan, but also its drawbacks, resulting in serious barriers to industrialization. In order to facilitate technology transfer, we critically discuss the practical feasibility of chitosan aerogels in potential applications compared to conventional and other biopolymer‐based porous or nonporous materials.

Cross-linking and trimethylsilylation successfully block off the hydrophilic NH and OH groups in chitosan nanofibers to produce a waterproof nanofibrous aerogel while keeping its nanoscale structural homogeneity intact. The unique microstructure of a three-dimensionally entangled nanofiber network exhibiting a combination of translucency, hydrophobicity, and non-brittleness is described.

YVO 4 :Bi 3+ ,Eu 3+ nanophosphor converts near ultraviolet light to red light and shows lower scattering loss for visible light and longterm photostability. Therefore, the authors produce urethane resin films containing YVO 4 :Bi 3+ ,Eu 3+ nanophosphors on soda-lime glass substrates as spectral shifters to understand the effects of doping of Bi 3+ and Eu 3+ into YVO 4 and the Bi 3+ concentration on photoelectric conversion efficiencies of a monocrystalline silicon photovoltaic module. Under ultraviolet and near infrared light radiation, the YVO 4 :Bi 3+ ,Eu 3+ films enhance the photoelectric conversion efficiency of the module through spectral down-shifting as compared to the bare glass substrate and the YVO 4 film. In contrast, the YVO 4 :Bi 3+ ,Eu 3+ films are not effective for improving the photoelectric conversion efficiency under the simulated solar light radiation. These results are discussed from the aspects of the optical transparency and the photoluminescence properties.