Regarding the catalytic properties of gold, the first ionization ability of gold is very large, and it is difficult to lose electrons, so the interaction force between gold and surface molecules is usually very weak. At temperatures below 200 °C, even highly reactive molecules, such as hydrogen and oxygen, are not easily adsorbed on the surface of single crystal gold. Since the adsorption of molecules on the catalyst surface is a prerequisite for the catalytic reaction, it can be considered that elemental gold does not have good activity for hydrogenation and oxidation reactions. Gold does not have very good catalytic activity. In fact, the prerequisite for the catalytic activity of gold catalysts is to prepare highly dispersed nano scale gold particles.
The characteristics of nano-gold catalysts: low temperature activity, good selectivity, and environmental friendliness.
An obvious feature of gold nanoparticles as catalysts is low temperature activity.
When the nano-gold catalyst catalyzes some reactions, it can be at room temperature or even below 0 °C, and the real good catalytic activity, such as catalytic CO oxidation and O3 decomposition, can be carried out at room temperature. In fact, the activity of gold catalysts for most reactions occurs below 230 °C. However, the activity of gold catalysts above 230 °C is significantly lower than that of other precious metal catalysts.
Nano gold particle catalysts have good selectivity when catalyzing certain reactions, and their catalytic properties are usually different from other noble metal catalysts.
For example, in the hydrogenation of CO2 catalyzed by Au/Zno catalyst, although its catalytic activity to methanol is slightly lower than that of commercial Cu/ZnO-Al2O3 catalyst, its selectivity is higher.
The nanogold powdercatalyst is environmentally friendly. Nano-gold catalysts can purify some polluted gases in the environment under normal temperature and humidity conditions without consuming too much thermal energy.
In terms of hydrogen energy generation, the catalyst can provide some new green synthesis methods and processing processes.