Increasing the Efficiency of CO Catalytic Conversion
Using a combination of tools at the Advanced Light Source (ALS) and other facilities, researchers probed specific mechanisms affecting the efficiency of catalysts for CO-to-CO2 conversion.Get more news about
,you can vist our website!
The work brings us closer to the rational design of more effective catalysts for cleaning up toxic CO exhaust and advances our understanding of fundamental catalytic reactions.
A better way to clear the air
The conversion of carbon monoxide (CO) into carbon dioxide (CO2) is important for cleaning up exhaust gases—mostly from vehicles that burn fossil fuels but also from stationary sources such as power plants and refineries. Platinum (Pt) catalysts are widely used to process CO into CO2, but the high cost of platinum-group metals has driven efforts to replace these materials with more earth-abundant alternatives.
One of the most promising ways of reducing the cost of metal catalysts is to mix them with oxygen-containing (oxide) compounds. In a previous investigation, researchers tested various mesoporous transition-metal oxides and loaded them with Pt nanoparticles. Each oxide exhibited enhanced CO-to-CO2 conversion activity, but the enhancement was largest for cobalt oxide.
To understand the origin of this enhanced activity, the researchers investigated the atomic and electronic structure of a Pt/cobalt oxide (CoO) model catalyst under operating conditions (i.e., in the presence of CO gas and/or oxygen). While their earlier study looked at platinum nanoparticles on oxide surfaces, in this study, the researchers used so-called “inverse” catalysts, where the oxide was formed on a platinum surface. The well-defined platinum surfaces enabled them to correlate the nanoscale surface structure, revealed by high-pressure scanning tunneling microscopy (HPSTM), with surface oxidation states, measured using ambient-pressure x-ray photoelectron spectroscopy (APXPS) at NSLS-II and the ALS.
APXPS at ALS Beamline 11.0.2 enables the identification of surface molecules and their chemical states as reactions take place in environments of oxygen and CO gas at pressures as high as several Torr. Thus, the researchers could intentionally modify the sample environment to carefully distinguish each spectroscopic feature and understand individual processes. Measurements at NSLS-II also probed these phenomenona on CoO films of different thicknesses. The results were combined with theoretical calculations performed at UCLA and the University of Central Florida.
