Cu 2 O/reduced graphene oxide/TiO 2 nanomaterial: An effective photocatalyst for azide‐alkyne cycloaddition with benzyl halides or epoxide derivatives under visible light irradiation

Isatin-Schiff base functionalized graphene oxide as a highly selective turn-on fluorescent probe for the detection of Pd(II) via photoinduced electron transfer pathway

We investigated the use of isatin-Schiff base functionalized graphene oxide (ISBGO) as a selective fluorescent chemosensor for the detection of palladium ions. Selectivity tests indicated that over 23 metal ions tested, ISBGO (λex = 340 nm, λem = 504 nm) showed the highest affinity for Pd(II), displaying a 10.1-fold enhancement. Also, interference tests proved that in the presence of both Pd(II) and other metal ions, there was still high fluorescence intensity and no considerable quenching occurred. According to DFT and TD-DFT calculations, photo-induced electron transfer (PET) is responsible for the turn-on response produced by the chemosensor. Coordination of Pd(II) with ISBGO in fact blocks PET from imine nitrogen of 3-iminoindolin-2-one moiety to the benzene ring, which in turn leads to a turn-on response. In addition, Job's plot analysis and Benesi-Hildebrand approach suggest that ISBGO preferably forms a 1:1 complex with Pd(II) with an association constant of 1.020 × 105 M-1. Moreover, FT-IR spectroscopy and DFT study showed that amide oxygen and imine nitrogen of 3-iminoindolin-2-one moiety acted as binding sites of ISBGO. High sensitivity, fast response, great degree of sensitivity, short life time, low detection limit of 32 nM combined with high association constant (Kf) of 1.020 × 105 M-1 and increased fluorescence quantum yield (Φf) of roughly 1.5-fold in the presence of Pd (II), highlight the role of ISBGO as an excellent probe for sensing Pd(II) in aqueous solution.

Copper-doped functionalized β-cyclodextrin as an efficient green nanocatalyst for synthesis of 1,2,3-triazoles in water

The synthesis of 1,2,3-triazoles with immobilized Cu(I) in thiosemicarbazide-functionalized β-cyclodextrin (Cu@TSC-β‐CD) as a supramolecular catalyst was discussed. The catalyst was characterized by Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) measurements. The catalyst showed high activity (up to 95% yields of triazole products under optimized reaction conditions), providing a one-pot, atom-economic, and highly regioselective green method for 1,2,3-triazoles synthesis in an azide-alkyne cycloaddition (AAC) protocol in water. High stability and no appreciable leaching of Cu(I) were observed, owing to its strong binding via the coordination with thiosemicarbazide functionality.

Copper Oxide-Based Photocatalysts and Photocathodes: Fundamentals and Recent Advances

This work aims at reviewing the most impactful results obtained on the development of Cu-based photocathodes. The need of a sustainable exploitation of renewable energy sources and the parallel request of reducing pollutant emissions in airborne streams and in waters call for new technologies based on the use of efficient, abundant, low-toxicity and low-cost materials. Photoelectrochemical devices that adopts abundant element-based photoelectrodes might respond to these requests being an enabling technology for the direct use of sunlight to the production of energy fuels form water electrolysis (H2) and CO2 reduction (to alcohols, light hydrocarbons), as well as for the degradation of pollutants. This review analyses the physical chemical properties of Cu2O (and CuO) and the possible strategies to tune them (doping, lattice strain). Combining Cu with other elements in multinary oxides or in composite photoelectrodes is also discussed in detail. Finally, a short overview on the possible applications of these materials is presented.