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A facile chemical synthetic route has been demonstrated for the synthesis of copper oxide nanoparticles decorated phosphate functionalized graphene oxide (CuO/PGO). The synthesized nanocatalyst was used as an efficient and active candidate for the synthesis of β-amino carbonyl compounds viaa green synthetic ultrasonic route. The structural properties of the samples were investigated by means of a number of sophisticated techniques like X-ray diffraction (XRD), Fourier-transform Infrared (FTIR) spectroscopy, High Resolution Transmission Electron Microscope (HRTEM), N2 adsorption-desorption measurements, X-ray photoelectron spectroscopy (XPS) analysis, Ammonia temperature programmed desorption analysis (NH3-TPD) and Raman spectroscopy. HRTEM analysis confirmed the presence of spherical CuO nanoparticles distributed uniformly throughout the PGO surface. XPS analysis demonstrated the presence of Cu2+ species and minor reduction of oxygen functional groups on GO. A higher surface area of 162 m2/g for CuO/PGO was found from N2 adsorption-desorption isotherms. Later on, the presence of acidic groups on CuO/PGO that play an essential role in the catalytic activity was examined by NH3-TPD and pyridine adsorbed IR analysis. The total acidity on the surface of synthesized nanocatalyst was found to be of 0.59 mmol g−1 which includes both Lewis as well as Bronsted acidic sites. A higher product yield of 95% in a shorter period of time of 15 min was achieved which is superior to many reported catalytic systems. A combined strategy involving greener and easier ultrasonic route and use of an efficient acidic graphene oxide-based catalyst resulted in higher catalytic activity and stability with good recyclability.

Phosphate functionalized graphene oxide (PGO), prepared by covalently bonding triethylphosphite on to the surface of graphene oxide (GO) via Arbuzov reaction has been demonstrated as an efficient catalyst for three component Biginelli condensation reaction with excellent yield (96%) under microwave condition. The PGO nanocatalyst was thoroughly characterized by Fourier transform infrared spectra (FTIR), FT-Raman spectroscopy, Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field-emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDS), N 2 adsorption/desorption study, Ammonia temperature-programmed desorption analysis (NH 3 -TPD) and Thermogravimetric analysis (TGA). The presence of acidic groups on PGO which play an important role in the catalytic transformation were measured by NH 3 -TPD analysis. Based on the catalytic results, a feasible catalytic mechanism has been proposed. Besides high catalytic activity, this nanocatalyst showed good recyclability, suggesting its potential applications for the synthesis of other important organic molecules.

A novel graphene oxide (GO)–SnO2–TiO2-based ternary nanocomposite was prepared via a one-step solvothermal process. The structure, morphology, and optical properties were characterized by a series of techniques, including X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS), UV-vis Diffuse Reflectance Spectroscopy (DRS), Photoluminescence, Raman spectroscopy, Nitrogen Adsorption–Desorption, and X-Ray Photoelectron Spectroscopy (XPS). Various microscopic images of the ternary nanocomposite showed that the SnO2 and TiO2 nanoparticles are firmly covered over GO, thereby increasing the surface area of the resultant nanocomposite. The photocatalytic activity of ternary GO–SnO2–TiO2 and binary GO–SnO2 and GO–TiO2 materials were studied through the photodegradation of congo red and methylene blue under solar radiation. The degradation efficiency of GO–SnO2–TiO2 was found to be 96% for methylene blue dyes within 60 min and 98% for congo red within 70 min, which is much higher than the binary composites. Furthermore, a photoelectrochemical study was performed to provide further insight into the photocatalytic activity, which further confirmed the superiority of the novel ternary nanocomposite in photocurrent generation. The enhanced photocatalytic properties of the ternary nanocomposite can be attributed to enhanced light absorption, efficient charge transfer process, high surface area, as well as superior durability of the composite. In addition, a possible reaction mechanism has been postulated. Our results have demonstrated that by carefully introducing GO with suitable metal oxides, highly efficient photocatalysts can be designed that would absorb a wider range of the solar spectrum.