The project "np-Gold" addressed a burning need to reduce harmful emissions produced by automobiles which emit toxic gases to the environment. This includes unburned hydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO). CO is particularly harmful and fatal at small concentrations, since it has a high affinity to hemoglobin in blood cells, replacing oxygen. Current catalytic converters comprised of platinum group metals are very efficient in converting the toxic gases to non-toxic counterparts, but NOT during the cold-start of the engine when more than 70 percent of all the harmful gas emissions from a single average drive are produced during.
Nanoparticulated gold is known for its high catalytic activity at low temperatures, however, it undergoes severe coarsening when exposed to elevated temperatures and as a result, loses its catalytic properties.
In this project, we proposed a novel approach to the formation of single crystalline nanoporous gold which can serve as a nanoparticulate Au-based catalyst. Our nanoporous gold formed via the proposed method exhibits superior thermal stability relative to classical nanoporous gold prepared by dealloying and retains coarsening due to the absence of grain boundaries. Thus, our nanoporous gold is catalytically active at low temperatures and retains its structure and functionality after exposure to high temperatures. The latter combined together may eventually allow gold to be used in the automotive catalytic converters industry, where currently used catalysts from the platinum group metals fail to fully convert toxic gases during the low temperatures regimes.
During this project, we have successfully developed a process to form the nanoporous gold in bulk quantities, specifically several mm-sized particles, that can be further incorporated into current automotive catalytic converters. We have also proven that our np-Gold exhibits enhanced thermal stability. The latter will enable our nanoporous gold particles to be easily embedded into current catalytic converter technology.
We trust that our nanoporous gold solution, applied within the automotive catalytic converter industry frameworks will have an environmental, health, and social impact. Our np-Gold has the potential to finally allow gold to be used in catalytic converters, which will solve the cold-start problem and lower the level of toxic emissions and the price of catalytic converters.
