We fabricated highly-sensitive non-enzymatic amperometric glucose biosensors using Pt, Cu2S, and SnO2 nanocrystal (NC)-carbon nanotube (CNT) hybrid nanostructures, where the NCs were grown in-situ on the CNTs by the solvothermal method. The synergetic combination of the electrocatalytic activity of the NCs and the electrical network formed through their direct binding with the CNTs enhances the H2O 2 and glucose sensing ability of the NC-CNT hybrid nanostructures. The photocatalytic degradation of aqueous 1,4-dioxane under visible light irradiation was achieved using Cu2S, CdSe, CdS NCs, and NC-CNT hybrid nanostructures. Ethylene glycol diformate and H2O2 were detected as intermediates, which eventually decompose into CO2 and H2O. The sensitivity, selectivity, degradation efficiency, and stability of these NCs and NC-CNT hybrid nanostructures demonstrated their potential for use as novel non-enzymatic glucose sensors and photocatalyst.