Fabrication, characterization, and evaluation of the cytotoxicity of platinum–rhodium nanocomposite materials for use in ammonia treatment

This work describes the oxidation of ammonia (NH3) at temperatures between 423 and 673 K by selective catalytic oxidation (SCO) over a Pt–Rh nanocomposite catalyst that was prepared by the co-precipitation of H2PtCl6 and Rh(NO3)3 in a tubular fixed-bed flow quartz reactor (TFBR). The catalysts were characterized using TEM, XRD, PSA, and CV. The experimental results reveal that at a temperature of 673 K and an oxygen content of 4%, approximately 98% of the NH3 was removed by catalytic oxidation over the Pt–Rh nanocomposite catalyst. N2 was the main product of the NH3-SCO process. The Pt–Rh nanocomposite-induced cytotoxicity to the human lung cell line, MRC-5, was tested, and cell survival was determined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetra-zolium (MTS) analysis in vitro. These results demonstrated that the Pt–Rh nanocomposite catalyst is only weakly cytotoxic to human lung cells.

Graphical AbstractThe cyclic voltammetry (CV) plots in this figure reveal that the fresh Pt–Rh nanocomposite catalyst exhibits a greater reversible redox capacity than does the aged Pt–Rh nanocomposite catalyst. The reduction peaks of the fresh and aged Pt–Rh nanocomposite catalysts occurred at 0.5 and − 0.1 V, respectively. This reversible redox ability may explain the substantial activity of the catalysts.Figure optionsDownload as PowerPoint slideResearch Highlights
► The oxidation of NH3 by SCO to produce N2 over a Pt-Rh nanocomposite material.
► The CV plots the Pt-Rh nanocomposite material exhibits a reversible redox capacity.
► The Pt-Rh nanocomposite material is only weakly cytotoxic to human lung cells (MRC-5).