Eye-Readable Detection and Oxidation of CO with a Platinum-Based Catalyst and a Binuclear Rhodium Complex

Toxic gases that are colorless and odorless, such as CO, are a major environmental concern and require early detection to prevent serious toxicological effects. In this study, a unique system (Pt/HMSs-BRC) was fabricated by combining a catalyst (Pt/hollow mesoporous silica spheres, Pt/HMSs) with a silica gel containing an adsorbed chromogenic probe (binuclear rhodium complex, BRC). The process is a simple method to prepare well-dispersed and uniform Pt nanoparticles. The Pt/HMSs-BRC materials demonstrated early CO detection and excellent catalytic performance for CO oxidation. The probe exhibited remarkable color modulation from gray-violet to light-yellow when exposed to CO concentration levels above 50 ppm, and the color of the chromogenic probe was fully recoverable. By a kinetics-assisted discrimination method and DFT calculations, it was found that the corner Pt sites are the dominant active sites for CO oxidation.