Titania doped by niobium was successfully synthesized via a modified evaporation-induced self-assembly method (EISA) as a support of IrO 2 for a solid polymer electrolyte water electrolyzer (SPEWE). The doping amount of niobium (5, 10, 20 at. %) was emphatically investigated to evaluate the effects on nanostructure, morphology, and oxygen evolution reaction (OER) activity of Nb-doped titania supported IrO 2. The high-resolution transmission electron microscopy (TEM) results show that IrO 2 supported by Nbdoped titania exhibits grain refinement and uniform dispersion. An investigation of the electrocatalytic activity by half-cell electrochemical testing reveals that the Nb-doped titania supported IrO 2 catalyst demonstrates significant OER activity. When the Nb content reaches 20 at. % in the support, the Nb-doped titania supported IrO 2 possesses the highest OER activity, which is superior to that of pristine titania supported IrO 2 and unsupported IrO 2 . The single-cell tests also prove that 20 at. % is the best Nb doping amount for titania supports of IrO 2 . It is found that the majority of the OER activity increase is due to the Nb-doping induced enhancement of the specific surface area and surface activity of transferring charge and species. The additional specific surface area and redox couples of Nb(IV)/Nb(V) are also responsible for this performance enhancement. Herein, the as-synthesized Nb-doped titania is considered to be a promising oxygen evolution catalyst support for SPEWE applications.

Food-borne nanoparticles have received great attention because of their unique physicochemical properties and potential health risk. In this study, carbon dots (CDs) formed during one of the most important chemical reactions in the food processing field, the Maillard reaction from the model system including glucose and lysine, were investigated. The CDs purified from Maillard reaction products emitted a strong blue fluorescence under ultraviolet light with a fluorescent quantum yield of 16.30%. In addition, they were roughly spherical, with sizes of around 4.3 nm, and mainly composed of carbon, oxygen, hydrogen, and nitrogen. Their surface groups such as hydroxyl, amino, and carboxyl groups were found to possibly enable CDs to scavenge DPPH and hydroxyl radicals. Furthermore, the cytotoxicity assessment of CDs showed that they could readily enter HepG2 cells while causing negligible cell death at low concentration. However, high CDs concentrations were highly cytotoxic and led to cell death via interference of the glycolytic pathway.

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