1：Experimental Design and Method Selection:

The study employed physical mixing of TiO2 and TiN nanoparticles to prepare composites, avoiding thermal procedures to prevent oxy-nitride formation and aggregation. Photocatalytic hydrogen evolution was tested under UV, visible, and combined UV/Vis light using methanol reformation in aqueous colloidal suspensions.

2：Sample Selection and Data Sources:

Commercial TiN (TiN(COM)) from US Nano Materials and laboratory-prepared TiN (TiN(CSIRO)) from CSIRO were used, along with Aeroxide? TiO2 P25 from Evonik. Samples were characterized using XRD, TEM, UV/Vis spectroscopy, BET surface area analysis, and XPS.

3：List of Experimental Equipment and Materials:

Equipment includes a Zetasizer Nano ZS for DLS, PANalytical X’Pert Pro MPD X-ray diffractometer for XRD, Varian Cary 5 UV/Vis spectrophotometer for solid-state UV/Vis, Agilent Technologies Cary 60 UV-Vis spectrophotometer for solution UV/Vis, Micromeritics Accelerated Surface Area and Porosimetry System for BET, Specs SAGE 150 spectroscope for XPS, JEOL 1400 and JEOL 2200 microscopes for TEM/HRTEM/EDS, and a photocatalytic reactor with a 350 W mercury arc lamp and various filters. Materials include TiN nanoparticles, TiO2 P25, methanol, water, HCl, NaCl, He, N2, Ar, and chloroplatinic acid.

4：Experimental Procedures and Operational Workflow:

Aqueous colloidal suspensions of TiO2 and TiN were prepared by ultrasonication at pH 5, mixed, stirred for 24 h, centrifuged, washed, and dried. For photocatalysis, 5 mg of composite was ultrasonicated in H2O:MeOH (3:1) mixture, deoxygenated with Ar, and irradiated in a quartz reactor with light sources and filters. H2 evolution was monitored using GC with a discharge ionization detector.

5：Data Analysis Methods:

Data were analyzed using FullProf software for XRD refinement, Tauc and Kubelka-Munk equations for band gap extraction, Micromeritics software for BET surface area, and statistical methods for error bars (standard deviation of repeat experiments).