Adaptive Restructuring toward Intrinsically Stable Rh Catalyst during Water-Gas Shift Reaction

Area of Science:

• Heterogeneous catalysis
• Materials science
• Surface chemistry

Background:

• Achieving intrinsic stability of reaction-formed catalytic sites is a major challenge in heterogeneous catalysis.
• CO-driven restructuring of metals into subnanometer clusters is known, but its electronic basis and catalytic mechanism are unclear.

Purpose of the Study:

• To investigate the restructuring of atomically dispersed Rh on CeO2 nanorods during the water-gas shift (WGS) reaction.
• To elucidate the electronic origins of the resulting catalytic site stability and the underlying catalytic mechanism.

Main Methods:

• In situ spectroscopy
• Kinetic analysis
• Density functional theory (DFT) calculations

Main Results:

• Atomically dispersed Rh spontaneously restructured into stable Rh3(CO)4 clusters during the WGS reaction, overcoming the activity-stability trade-off.
• The stable Rh3(CO)4 clusters sustained performance over 5000 hours at 300°C without deactivation.
• Intrinsic stability originates from Rh-CO back-donation stabilizing the cluster and surface hydrides facilitating a lower activation barrier via a concerted pathway.

Conclusions:

• Reactive atmospheres can guide catalytic sites toward configurations that balance structural stability and catalytic function.
• The study reveals the dual origins of intrinsic stability in reaction-formed catalytic sites, crucial for designing robust catalysts.