1：Experimental Design and Method Selection:

The study involved preparing copper-promoted anatase-type TiO2 photocatalysts via wet impregnation and ethanol reduction methods. The experimental design focused on comparing materials with and without pre-calcination of TiO2 at 600°C to understand the influence on photocatalytic activity for nitrate reduction and oxalic acid degradation under UV light. Theoretical models included Langmuir and Freundlich isotherms for adsorption studies, and mechanisms for photocatalytic reduction were proposed based on electron-hole pair generation and redox reactions.

2：Sample Selection and Data Sources:

Photocatalysts were synthesized using TiO2-UV100 (Hombikat, Sachtleben Chemie) as the support, with Cu(NO3)2·3H2O as the copper precursor. Samples included Cu/TiO2, Cu/600TiO2, Cu2O/TiO2, and Cu2O/600TiO2, all with nominal 2.5 wt% Cu loading. Data were sourced from laboratory experiments involving characterization and photocatalytic tests.

3：5 wt% Cu loading. Data were sourced from laboratory experiments involving characterization and photocatalytic tests. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment: X’Pert Pro Diffractometer (PANalytical) for XRD, Tristar-3000 instrument (Micromeritics) for BET surface area, STA 780 thermal analyser for DTA, SUPRA 40VP microscope (Carl Zeiss) for FESEM, JOEL JEM-2000 EX microscope for HRTEM, Cary 60 UV-Visible spectrometer (Varian) for diffuse reflectance, TPDRO 1100 instrument for TPR and N2O chemisorption, 1750 series FTIR spectrometer (Perkin-Elmer) for CO adsorption, Kratos AXIS Ultra DLD XPS spectrometer for XPS, Lambda 25 UV-visible spectrometer (Perkin-Elmer) for concentration measurements, Dionex DX-120 ion chromatography for ion analysis, and a batch reactor with Heraeus BQ 512 E UV lamp (400 W) for photocatalytic tests. Materials: TiO2-UV100, Cu(NO3)2·3H2O, ultra-pure deionised water (MilliQ ≥ 18.2 MΩ·cm), anhydrous ethanol, BaSO4, CO gas, nitrate and oxalic acid solutions, and various chemicals for analytical methods.

4：2 MΩ·cm), anhydrous ethanol, BaSO4, CO gas, nitrate and oxalic acid solutions, and various chemicals for analytical methods. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Photocatalysts were prepared by dispersing TiO2 in water or ethanol, adding Cu precursor, stirring, evaporating, drying at 60°C, and calcining at 400°C or 350°C. Pre-calcined samples involved heating TiO2 at 600°C before impregnation. Characterization included XRD for crystal structure, BET for textural properties, DTA for thermal analysis, SEM/TEM for morphology, UV-Vis for optical properties, TPR for reducibility, N2O chemisorption for Cu dispersion, FTIR for CO adsorption, and XPS for surface composition. Adsorption tests involved shaking catalysts with nitrate or oxalic acid solutions, centrifuging, filtering, and measuring concentrations. Photocatalytic tests were conducted in a batch reactor with UV illumination, N2 purging, sampling at intervals, and analyzing concentrations via ion chromatography and spectrophotometry.

5：Data Analysis Methods:

Data were analyzed using Scherrer equation for crystallite size from XRD, BET theory for surface area, Langmuir model for adsorption isotherms with chi-square test for fit quality, and first-order kinetics for photocatalytic rate constants. Statistical analysis included regression and chi-square tests for adsorption data fitting.