Carbon dioxide hydrogenation on Ni(110)

Area of Science:

• Surface Science
• Catalysis
• Computational Chemistry

Background:

• Heterogeneous catalysis is crucial for organic synthesis.
• Carbon dioxide (CO 2) is a key reactant in many catalytic processes.
• Understanding reaction mechanisms at the atomic level is essential for catalyst design.

Purpose of the Study:

• To elucidate the atomic-level mechanism of CO 2 hydrogenation on Ni(110).
• To explain the lower activation barrier for CO 2 hydrogenation on Ni compared to Cu.
• To provide insights into the catalytic activity of NiCu alloys.

Main Methods:

• Ultrahigh vacuum surface science techniques
• Density functional theory (DFT) calculations
• High pressure reactivity tests

Main Results:

• CO 2 initially bonds via carbon at 90 K, becoming negatively charged.
• Upon heating and H addition, CO 2 flips to bond via oxygen atoms, forming a formate intermediate.
• Ni exhibits a significantly smaller CO 2 hydrogenation barrier than Cu.

Conclusions:

• The key step in CO 2 hydrogenation on Ni is a change in CO 2 coordination to the surface.
• This mechanism explains the high catalytic activity of Ni and NiCu alloys.
• Detailed mechanistic understanding can advance heterogeneous catalytic organic synthesis.