1：Experimental Design and Method Selection:

The study involved synthesizing group 4 metal nitride nanocrystals via a solid-state metathesis reaction and comparing their photothermal transduction efficiencies to commercially purchased Au nanorods under 850 nm illumination. Computational studies using a finite element method were conducted to understand the efficiency trends.

2：Sample Selection and Data Sources:

Transition metal nitride nanocrystals (TiN, ZrN, HfN) with an average diameter of ～15 nm were prepared. Citrate-stabilized Au nanorods were purchased from Nanocomposix.

3：List of Experimental Equipment and Materials:

Materials included titanium dioxide, zirconium dioxide, hafnium dioxide, magnesium nitride, hydrochloric acid, and citrate-stabilized Au nanorods. Equipment included a Rigaku Ultima IV X-ray diffractometer, Agilent CARY 5000 spectrometer, Zetasizer Nano Series Nano-ZS, Hitachi-9500 electron microscope, and a continuous 850 nm Solis LED source.

4：Experimental Procedures and Operational Workflow:

The metal nitride nanoparticles were synthesized, characterized, and their photothermal properties were measured under continuous irradiation. Temperature changes were monitored, and computational analysis was performed to simulate optical properties.

5：Data Analysis Methods:

Photothermal transduction efficiencies were calculated using a model developed by Roper et al. Computational studies were conducted using Comsol MultiPhysics to simulate the optical spectra of the nanocrystals.