The support material, referred to as "contactor", was impregnated with branched polyethyleneimine (PEI, Mw ~ 800) using a proprietary process. TiN nanoparticles (NPs) were drop-cast onto the contactor from a mixture of 1 mL methanol, 5 µL of PEI, and 10 mg TiN. The additional PEI improved the suspension of TiN in methanol and enhanced its adhesion to the contactor. The resulting contactor system consisted of 2.5 wt% TiN and ~12 wt% PEI, the latter verified by thermogravimetric analysis using published methods. The TiN NPs were acquired from US Research Nanomaterials, Inc. A transmission electron microscopy image (Supporting Information, Figure ) reveals a heterogeneous morphology and an average size distribution centered ~20 nm, with a broad absorption spectrum from 380 -750 nm obtained from diffuse reflectance UV-Vis absorption spectroscopy.