1：Experimental Design and Method Selection:

A simple solution-chemistry method was used to synthesize Cu2O-rGO-x composites with varying rGO contents (1%, 5%, 10%). The method involved mixing CuCl2, SDS, and GO, followed by addition of NaOH and NH2OH·HCl, stirring, and drying.

2：Sample Selection and Data Sources:

Samples included pristine Cu2O and Cu2O-rGO-x composites. Graphene oxide was prepared using a modified Hummer's method.

3：List of Experimental Equipment and Materials:

Equipment included XRD (PANalytical X’Pert PRO), SEM (JSM-7000F, JEOL), TEM (JEM-1400, JEOL), PL (HR800, HORIBA), XPS (Kratos AXIS Ultra DLD), UV-Vis spectrophotometer (Cary 100, Varian), batch reactor, Xe lamp (Model 66142, Newport), GC (GC-430, Bruker; GC-2010 Plus, Shimadzu). Materials included CuCl2, SDS (Sigma), NaOH, NH2OH·HCl (Alfa Aesar), GO, deionized water, CO2 gas.

4：Experimental Procedures and Operational Workflow:

Synthesis involved mixing reagents, stirring, centrifugation, and drying. Characterization used XRD, SEM, TEM, PL, XPS, UV-Vis. Photocatalytic tests involved dispersing catalyst in water, saturating with CO2, irradiating with visible light, and analyzing products with GC.

5：Data Analysis Methods:

Data were analyzed using spectroscopic techniques and GC; band gaps were calculated from UV-Vis spectra, and methanol yields were quantified.