1：Experimental Design and Method Selection:

The study involved collecting sandstone samples from Lang Mountain Danxia landform, characterizing them using various microanalytical techniques (POM, ESEM, EDX, EPMA, micro-Raman, micro-XRD, XRF, HRTEM), and conducting photoelectrochemical and photocatalytic experiments on synthetic hematite, anatase, and their coupled material to simulate environmental effects.

2：Sample Selection and Data Sources:

Reddish sandstone samples were collected from seven sites around Lang Mountain, Hunan province, China. Samples were prepared as thin sections or ground powder for analysis.

3：List of Experimental Equipment and Materials:

Equipment included polarizing optical microscope (LV100POL, Nikon), environmental scanning electron microscopy (Quanta 650FEG, FEI), energy-dispersive X-ray analysis, electron probe microanalyzer (EPMA-1720, Shimadzu), micro-Raman spectra (Renishaw inVia Reflex), micro-X-ray diffraction (Rapid IIR, Rigaku), X-ray fluorescence spectrometer (Advant'XP+, Thermo ARL), high-resolution transmission electron microscopy (TECNAIF 20, FEI), UV-vis spectrophotometer (UV-3600 Plus, Shimadzu), electrochemical apparatus (CHI 660C, Chenhua), and others. Materials included synthetic Fe2O3, TiO2, FTO glass, and various chemicals (e.g., acetone, ethanol, nitric acid, tetrabutyl titanate, acetylacetone, methyl orange, FeCl3, NaNO3, Na2SO4).

4：4). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Samples were prepared by gluing with resin, cutting into thin sections, or grinding into powder. Synthetic electrodes were prepared using sol-gel and hydrothermal methods. Characterizations were performed using the listed equipment. Photoelectrochemical measurements used a three-electrode configuration with simulated sunlight, and photocatalytic experiments involved degrading methyl orange dye under similar conditions.

5：Data Analysis Methods:

Data were analyzed using techniques such as XRD pattern matching, Raman spectra comparison, TEM image processing with Digital Micrograph software, UV-vis DRS with Tauc's plot for band gap calculation, and linear sweep voltammetry for photocurrent measurements.