1：Experimental Design and Method Selection:

The study uses thermal decomposition of a precursor complex synthesized from cadmium nitrate and hexamethylenetetramine in ethanol at room temperature, followed by calcination at 500°C for 2 hours to produce CdO nanoparticles. Characterization techniques include elemental analysis, mass spectrometry, FTIR, TGA, XRD, SEM, HRTEM, N2 physisorption, and SAED.

2：Sample Selection and Data Sources:

The precursor is synthesized from analytical grade Cd(NO3)2·6H2O, hexamethylenetetramine, and ethanol obtained from Sigma Aldrich. No further purification is done.

3：List of Experimental Equipment and Materials:

Equipment includes Flash 2000 Thermo Scientific analyzer for elemental analysis, Micro-Mass LCT Premier mass spectrometer for mass spectrometry, PerkinElmer Spectrum Two UATR-FT-IR spectrometer for FTIR, Pyris 6 PerkinElmer TGA 4000 thermal analyzer for TGA, Bruker D8 Advance X-ray diffractometer for XRD, JEOL JSM-7600F field-emission scanning electron microscope for SEM and EDX, JEOL JEM-2100F microscope for TEM and HRTEM, Micromeritics ASAP 2020 instrument for N2 physisorption. Materials include Cd(NO3)2·6H2O, hexamethylenetetramine, ethanol, ceramic crucible, silica gel for desiccation.

4：Experimental Procedures and Operational Workflow:

Precursor synthesis involves dissolving HMTA in ethanol with sonication, adding cadmium nitrate solution dropwise under stirring, filtering and washing the precipitate, and drying. CdO synthesis involves grinding the precursor, calcining in a furnace at 500°C for 2 hours, and cooling. Characterization involves specific procedures for each technique as described.

5：Data Analysis Methods:

Particle size calculated using Debye-Scherrer equation from XRD data, size distribution from TEM images using ImageJ software, surface area and pore size from BET and BJH methods using N2 physisorption data.