1：Experimental Design and Method Selection:

The study employed solvothermal synthesis to prepare the zinc(II) coordination polymer [Zn3(HL)6]n (1). Characterization methods included single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and solid-state diffuse-reflectance UV/Vis spectroscopy. Photocatalytic activity was tested using methylene blue degradation under UV light with H2O2 as an oxidant.

2：1). Characterization methods included single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and solid-state diffuse-reflectance UV/Vis spectroscopy. Photocatalytic activity was tested using methylene blue degradation under UV light with H2O2 as an oxidant. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Raw materials included Zn(NO3)2·6H2O, 3-hydroxypyridine-2-carboxylic acid, and gallic acid. Methylene blue (MB) was used as the model dye contaminant. Data were collected from synthesized crystals and dye solutions.

3：List of Experimental Equipment and Materials:

Equipment included Perkin–Elmer 240C elemental analyzer, Nicolet IR Avatar 360 spectrophotometer, Cary 60 UV/Vis Spectrophotometer, NETZSCH STA-449F3 TGA instrument, Rigaku D/Max-2500PC powder X-ray diffractometer, Agilent GeminiE single crystal diffractometer, and Puxi UV 1901 UV/Vis spectrophotometer. Materials included KBr pellets, BaSO4 plate, ethanol, H2O2 solution, and a 250 W Hg lamp.

4：Experimental Procedures and Operational Workflow:

Synthesis involved mixing reagents in ethanol, heating in a Teflon-lined stainless steel vessel at 85 °C for 24 h, and cooling slowly. Characterization steps included crystal structure determination, IR and UV/Vis measurements, TGA, and PXRD. Photocatalysis involved adding catalyst and H2O2 to MB solution, stirring in dark for equilibrium, irradiating with UV light, sampling at intervals, centrifuging, and measuring absorbance at 664 nm.

5：Data Analysis Methods:

Crystal structure was solved using SHELX package. Photocatalytic data were fitted to first-order kinetics model ln(C/C0) = kt. Bandgap was estimated using Kubelka-Munk function from diffuse reflectance data.