1：Experimental Design and Method Selection:

The study involved the synthesis of CuO/SiO2:rGO nanocomposites via a simple low temperature wet-chemical method. The structure, purity, functional groups, and morphology were characterized using XRD, FTIR, FESEM, and TEM.

2：Sample Selection and Data Sources:

The samples included CuO, CuO/SiO2, and CuO/SiO2:rGO nanocomposites in various ratios.

3：List of Experimental Equipment and Materials:

Equipment used included Xpert-Pro diffractometer, UV–Vis spectrophotometer, Jobin–Yvon spectrometer, ATR-FTIR, FE-SEM, and TEM. Materials included graphite powder, sodium nitrate, sulphuric acid, potassium permanganate, hydrogen peroxide, thiourea, ferrous sulphate heptahydrate, 3-aminopropyldimethoxysilane, copper chloride dihydrate, ammonia, hydrochloric acid, and deionised water.

4：Experimental Procedures and Operational Workflow:

The synthesis involved preparation of SiO2 nanospheres, CuO/SiO2 composite, amine modified CuO/SiO2 composites, and CuO/SiO2:rGO nanocomposites. Photocatalytic activity was evaluated by degradation of MB under visible light, and electrochemical performance was assessed using cyclic voltammetry and galvanostatic charge–discharge techniques.

5：Data Analysis Methods:

The data were analyzed using Kubelka–Munk function for band gap calculation, and specific capacitance was calculated from CV and GCD data.