1：Experimental Design and Method Selection:

The study utilized a biotemplate method with China rose petals to synthesize Co3O4 nanosheets. The method involved impregnation of cobalt nitrate solution into the petals followed by calcination.

2：Sample Selection and Data Sources:

Fresh China rose petals were used as the biotemplate. The synthesized Co3O4 nanosheets were characterized using various techniques including XRD, FT-IR, SEM, TEM, and nitrogen adsorption.

3：List of Experimental Equipment and Materials:

Equipment included a Rigaku Ultima IV XRD, Nicolet 380 FT-IR spectrometer, Zeiss sigma 500 FESEM, JEM-2010F FETEM, and a Micromeritics ASAP2460 system for nitrogen adsorption. Materials included cobalt nitrate, hydrogen peroxide, hydrochloric acid, methylene blue, and ethanol.

4：Experimental Procedures and Operational Workflow:

Petals were pretreated, soaked in cobalt nitrate solution, filtered, dried, and annealed to produce Co3O4 nanosheets. Photocatalytic activity was tested by degrading methylene blue under xenon lamp irradiation.

5：Data Analysis Methods:

The photocatalytic degradation rate was calculated based on absorbance measurements at 664 nm using a UV-3200Pc spectrophotometer.