Lanthanide-doped upconversion nanoparticles (UCNPs) are promising for applications as wide as biological imaging, multimodal imaging, photodynamic therapy, volumetric displays, and solar cells. Yet, the weak and narrow absorption of lanthanide ions poses a fundamental limit of UCNPs to withhold their brightness, creating a long-standing hurdle for the field. Dye-sensitized UCNPs are emerging to address this performance-limiting problem, yielding up to thousands-fold brighter luminescence than conventional UCNPs without dye sensitization. In their configuration, organic dyes with spectrally broad and intense absorption are anchored to the surface of UCNPs to harvest the excitation light energy, which is then transferred via Förster and/or Dexter mechanisms across the organic/inorganic interface to the lanthanides incorporated in UCNPs (with or devoid of a shell) to empower efficient upconversion. This tutorial review highlights recent progress in the development of dye sensitized UCNPs, with an emphasis on the theory of energy transfer, the geometric classification of the dye sensitized core and core/shell nanocrystals, and their emerging photonic and biophotonic applications. Opportunities and challenges offered by dye sensitized UCNPs are also discussed.

In this report, a novel approach for exfoliation of Co–Al layered double hydroxides (LDHs) in aqueous solution of L-asparagine was proposed. L-Asparagine is a water-soluble amino acid whose carbonyl groups would have a strong interaction with the LDH host layers and the amino groups might weaken the interlayer interactions. This simple method did not need reflux at high temperature, overcame the drawback of using organic solvents, and even resulted in a stably stored colloidal suspension of 2D nanosheets. Besides, the peroxidase-like activity of the exfoliated Co–Al LDH (Co–Al ELDH) was enhanced compared with unexfoliated LDH. Co–Al ELDH could rapidly catalyze oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue color reaction. On this basis, simple, rapid and selective colorimetric methods for H₂O₂ and glucose detection were developed. The presented means was used for glucose detection in fruit juices and fine results were obtained.

Porous Sb–SnO₂nanowires were synthesized as a support for IrO₂by an electrospinning method. The thus prepared catalyst exhibits enhanced mass activity toward OER.

Proton exchange membrane steam electrolyzers suffer from insufficient catalyst activity and durability due to the slow reaction kinetics for oxygen evolution reaction (OER) and poor durability under harsh operating environments. Aiming at enhancement of oxygen electrode kinetics and durability, composite support materials for iridium oxide are synthesized via in situ phosphorization reaction on tin doped indium oxide and possess functionalities of high electronic and intrinsic proton conductivity. At 130 °C under a water vapor atmosphere an overall conductivity of 0.72 S cm⁻¹ is achieved with a contribution of around 10⁻² S cm⁻¹ proton conductivity. The support structure of three-dimensionally ordered hexagonal arrays displays a high specific surface area of 180 m² g⁻¹. Benefiting from the mixed conductivities and porous structure in the composite support materials, the supported IrO₂ catalysts exhibit about five times enhancement of the OER activity in acidic electrolytes. The improved catalytic performance for the OER was further confirmed by PEM electrolyzer tests at 130 °C. A test of such a steam electrolyzer cell at 350 mA cm⁻² shows good durability within a period of up to 1150 hours.