Cu₂O microspheres were prepared by a room-temperature liquid-phase method using glucose as the reducing agent and ethylenediaminetetraacetic acid as the morphology control agent. After that, Au nanoparticles were grown on the surface of Cu₂O microspheres by room temperature liquid-phase method with sodium citrate as the reducing agent, and Cu₂O/Au micro-nanostructures were successfully fabricated. The phase composition of the samples was characterized by X-ray powder diffraction (XRD), and the morphology and size of the micro-nanostructures were analyzed by scanning electron microscopy (SEM). Photocatalytic performance showed that the degradation rate of methyl orange (MO) by Cu₂O/Au micro-nanostructures reached as high as 87% under visible light irradiation for 90 min. Based on the heterojunction structure between Cu₂O and Au interface, the enhancement mechanism of the photocatalytic performance of the micro-nanostructures was analyzed and discussed.

Optimization of photoelectrochemical (PEC) performance for electrode is very important to efficiently utilize solar energy in the form of chemical energy. The aim of this study is to optimize the PEC performance of TiO₂ nanowire array electrodes via the optimization of Na₂SO₃ and Na₂SO₄ electrolytes. The electrode shows significant improvement for the PEC performance in Na₂SO₃ electrolyte with a photocurrent density of 0.8 mA/cm², which is 5 times higher than that in Na₂SO₄ electrolyte. The incident photon-to-current conversion efficiency obtained in Na₂SO₃ electrolyte is 14.7% at λ = 390 nm, which is 2.6 times higher than that in Na₂SO₄ electrolyte. The Mott-Schottky and electrochemical impedance spectroscopy measurements experimentally show that the improved PEC performance is attributed to the efficient separation of photo-generated electrons and holes induced by the consumption of holes by ${\mathrm{S}\mathrm{O}}_3^{2-}$. The results of this study provide a promising strategy to improve the PEC performance of electrode by choosing the optimal electrolyte.

A novel porous CuO/Cu₂O composite hollow sphere assembled with one-dimensional (1D) nanostructures was successfully synthesized by a facile one-pot surfactant and template-free hydrothermal method. The electrochemical performance evidently demonstrated that the achieved porous CuO/Cu₂O composite hollow sphere was a very effective structure for solving the large volume expansion problem, which was serious issue for metal oxide anode materials. Compared to the initial cycle, the porous CuO/Cu₂O composite hollow spheres maintain a high reversible capacity of 680 mAh/g after 500 cycles at 100 mA/g without capacity fading. Meanwhile, the porous CuO/Cu₂O composite hollow spheres exhibit a good rate capability. The reversible capacity and cycling life significantly superior to those of reported CuO and Cu₂O nanostructures as well as CuO/Cu₂O h composite nanostructures, and the capacity fade was significantly inhibited. The excellent electrochemical performance of the CuO/Cu₂O h composite hollow spheres for anode materials in lithium-ion (Li⁺) batteries are attributed to the efficient diffusion of Li⁺ and electron facilitated by porous and 1D nanostructures, which promotes the diffusion of Li⁺ and electrons, effectively mitigates the volume changes caused by mesopores and internal hollow spaces, and the synergistic effect between CuO and Cu₂O within the porous CuO/Cu₂O hollo composite hollow spheres.