1：Experimental Design and Method Selection:

The composite materials were synthesized in only one step by chemical coprecipitation and thermal hydrolysis of urea, dried at 80°C, and characterized using various techniques including XRD, SEM, FTIR, UV-Vis, DRS, XPS, and N2 physisorption. Photocatalytic activity was assessed under UV-light irradiation in a home-made reactor.

2：Sample Selection and Data Sources:

Precursor salts Zn(NO3)2·6H2O (J.T. Baker 99.6% purity) and ZrCl4 (Sigma Aldrich, 98%) were used. Samples included HDZCT, ZrO2, and composites with 5, 8, and 10 mol% ZrO

3：6% purity) and ZrCl4 (Sigma Aldrich, 98%) were used. Samples included HDZCT, ZrO2, and composites with 5, 8, and 10 mol% ZrOList of Experimental Equipment and Materials:

2. 3. List of Experimental Equipment and Materials: Equipment included Bruker D2 PHASER diffractometer, Quantachrome Autosorb-3B for N2 physisorption, JEOL JSM-7600F SEM, Affinity-1 Shimadzu FTIR spectrometer, VARIAN CARY-100 UV-Vis spectrophotometer, K-alpha Thermo Fischer Scientific XPS spectrometer, UV-Pen Ray mercury lamp, VARIAN CARY 100 spectrophotometer for phenol concentration monitoring, TOC-V-CSH/CSN Shimadzu Analyzer for TOC analysis, Fluorolog3 Horiba Spectrofluorometer for fluorescence studies, and various glassware and filters.

4：Experimental Procedures and Operational Workflow:

Synthesis involved dissolving precursor salts in bi-distilled water, heating at 80°C with stirring and reflux for 36 hours, filtering, washing, drying at 80°C, and pulverizing. Photocatalytic tests used 1g/L catalyst in 40 ppm phenol solution, stirred in dark for 1 hour, then irradiated with UV light for 6 hours with airflow. Aliquots were collected and filtered for analysis.

5：Data Analysis Methods:

XRD patterns analyzed for crystal size using Scherrer equation and lattice parameters by Bragg formula. BET method used for surface area. UV-Vis data analyzed using Lambert-Beer law for concentration profiles. Kinetic rate constants calculated assuming pseudo-first-order reaction. XPS data deconvoluted for elemental analysis.