1：Experimental Design and Method Selection

The study involved the synthesis of Cu2O cubes, followed by the deposition of CuO and Au nanodomains to form heterostructures. The photocatalytic activity and stability of these heterostructures were then evaluated.

2：Sample Selection and Data Sources

Cu2O cubes were synthesized using a previously reported method. The samples were characterized using various techniques including XRD, TEM, SEM, UV-vis spectroscopy, XPS, PL, BET, and ESR.

3：List of Experimental Equipment and Materials

Chemical reagents were of analytical grade. Equipment included a Bruker D8 Discover diffractometer, FEI Tecnai G2 F20 S-TWIN microscope, Hitachi S4800 scanning electron microscope, PE Lambda 650s UV-vis spectrometer, Escalab 250 Xi spectrometer, PE-LS55 fluorescence spectrophotometer, Quantachrome NOVA4200e analyzer, and Bruker A300 electron paramagnetic resonance spectrometer.

4：Experimental Procedures and Operational Workflow

The synthesis involved the fabrication of Cu2O cubes, followed by the preparation of CuO/Cu2O and Au/CuO/Cu2O heterostructures. Photocatalytic activity was tested by degrading methyl orange under visible light irradiation.

5：Data Analysis Methods

Photocatalytic activity was evaluated based on the absorption spectra of the dyes. Photocurrent measurements were conducted using an electrochemical workstation.