Copper oxide has aroused great concern in energy storage fields due to its properties of high theoretical capacitance, low cost and mild toxicity. However, its wide application still remains challenges owing to its poor electrical conductivity and unstable cycling life. Binder-free foam electrodes possess abundant porous structures and high specific surface area, which could get good contact with electrolyte. Herein, we demonstrate Ag nanoparticles decorated Cu_xO nanowires grown spontaneously on copper foam (CF) electrode for asymmetric supercapacitor. The skeleton structure of CF provides large amounts of active sites for the growth of Cu_xO nanowires. Moreover, Ag nanoparticles further decrease the internal resistance and enhance the electrochemical performance. Ag/Cu_xO/CF-40 electrode presents a high area specific capacitance of 1192 mF cm⁻² at 2 mA cm⁻² and the influence of surface capacitance-dominated process and diffusion-controlled process are discussed in detail. Besides, the energy density of the as-prepared asymmetric supercapacitor (ASC) reaches 46.32 μWh cm⁻² at a power density of 3.00 mW cm⁻². A 2V LED is lighted successfully by two ASC in series. This work provides a new strategy to prepare low internal resistance and binder-free flexible Ag/Cu_xO/CF electrode, which demonstrates a good potential application in flexible supercapacitors or other wearable electronic devices.

The CeVO₄/graphitic C₃N₄ composites have exhibited much enhanced photocatalytic property for degrading methylene blue (MB) pollutant under visible light irradiation compared with single-phase g-C₃N₄ or CeVO₄. The composite S5 obtained from an optimized mass ratio (5%) of CeVO₄ to dicyanamide (DCDA) exhibits the highest photocatalytic activity. Here, ternary Ag/CeVO₄/g-C₃N₄ composites denoted as X%Ag/S5 were prepared by an ultrasonic precipitation method to improve the photocatalytic property of S5. The TEM images show that CeVO₄ and Ag nanoparticles are well distributed on the layered g-C₃N₄, which agree well with the XRD results. The UV spectra show that the 7%Ag/S5 sample has the widest absorption range and the enhanced absorption intensity under visible light irradiation. The corresponding band gap of 7%Ag/S5 (2.5 eV) is much lower than that of S5 (2.65 eV). The corresponding k value of 7%Ag/S5 is much higher than those of g-C₃N₄ and CeVO₄. The degradation experiments for MB solution suggest that the 7%Ag/S5 sample has the optimal photocatalytic performance, which can degrade MB solution completely within 120 min. The enhanced photocatalytic property of the composites is ascribed to not only the effect of heterojunction structure, but also the surface plasma resonance effect of Ag nanoparticles.