In this study, Cu 2 O/CuO/reduced graphene oxide (rGO) was synthesized through a rapid and convenient microwave-assisted hydrothermal method . The crystal structure and morphology of the as-prepared product were characterized using X-ray diffraction (XRD), field-emission-scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy , and X-ray photoelectron spectroscopy (XPS). The electrochemical performance of the novel Cu 2 O/CuO/rGO biosensor was investigated via cyclic voltammetry . The biosensor was evaluated for ascorbic acid (AA) detection and exhibited a wide linear range of 100 μM–1000 μM, a low detection limit of 0.301 μM, and a sensitivity of 1375.486 μA mM −1 cm −2 .
Conventional metal oxide semiconductor gas sensors often suffer from high operating temperatures, low selectivity, and complex synthesis processes for NO2 detection. In this work, reduced graphene oxide (rGO) nanosheets are coated on NaOH-etched Cu2O/CuO urchin-like spheres to form Cu2O/CuO@rGO composites via a one-step green synthesis method at room temperature (RT). The gas sensor based on this material has been utilized for detecting NO2 at RT (25 °C), and the effects of Cu2O addition and reaction time on the morphology as well as gas-sensing properties of the as-prepared sensor are investigated. Of interest, the sensor based on the 550Cu2O/CuO@rGO-5 composite has an ultra-high response (S = 871) to 5 ppm NO2 gas at RT with a response/recovery time of 32/73 s, and the detection limit is as low as 90.6 ppt. In addition, the gas sensor shows excellent selectivity and repeatability. The excellent sensing performance of the as-prepared 550Cu2O/CuO@rGO sensor is attributed to the framework structure of Cu2O/CuO@rGO, the urchin-like hierarchical structure of the Cu2O/CuO and the synergistic effect of the p–p (Cu2O–CuO) heterojunction. This exploration of the present work offers a good reference for mass, green, and low-power sensing material preparation.
Ternary copper oxides/reduced graphene oxide (Cu 2 O-CuO-RGO) composites were successfully synthesized in situ by a self-assembly solvothermal method in a water-ethanol mixture and used directly as the anode material for lithium ion batteries . The Cu 2 O-CuO-RGO composites delivered a reversible capacity of 842.5 mAh g −1 after 80 cycles at a current density of 100 mA g −1 , and after every 10 cycles at current densities of 100, 200, 500, 1000, 2000, 5000 and 100 mA g −1 , respectively, the specific capacities of the composites were approximately 840, 723, 511, 402, 336, 224, and 703 mAh g −1 , respectively. The improved electrochemical performance of the composites is closely related to its sandwich structure, with multicomponent Cu 2 O-CuO nanospheres adhering tightly to both sides of RGO nanosheets . This structure could shorten the transport pathways for both electrons and lithium ions , prevent the RGO nanosheets from stacking, enhance the electrical conductivity and accommodate the volume expansion that occurs during prolonged cycling.