Methanol decomposition on Ni(111) and O/Ni(111)

Area of Science:

• Surface science
• Chemical kinetics
• Heterogeneous catalysis

Background:

• Methanol decomposition is crucial for chemical synthesis.
• Understanding surface reactions on nickel is key for catalyst design.
• The role of oxygen in methanol decomposition on Ni(111) requires detailed investigation.

Purpose of the Study:

• To investigate methanol decomposition pathways on Ni(111) surfaces.
• To elucidate the influence of oxygen on methanol decomposition kinetics and surface intermediates.
• To characterize the bonding and desorption of reaction products.

Main Methods:

• Temperature-programmed desorption (TPD) to analyze gas-phase products and surface species.
• Temperature-dependent sum frequency generation (SFG) spectroscopy to identify surface intermediates and bonding.
• Utilizing Ni(111) single crystal surfaces under ultra-high vacuum conditions.

Main Results:

• Methanol decomposition proceeds via sequential O-H and C-H bond cleavage, forming methoxy and surface hydrogen.
• No C-O bond scission was observed, limiting reaction pathways.
• Surface oxygen stabilizes hydrogen as hydroxide (OH) and slightly increases dissociation temperatures for O-H and C-H bonds.
• CO desorbs between 350-400 K, with its vibrational frequency blueshifted due to increased mobility.

Conclusions:

• Methanol decomposition on Ni(111) is primarily governed by C-H and O-H bond breaking.
• Surface oxygen significantly modifies the reaction mechanism by stabilizing intermediates and altering desorption temperatures.
• The study provides fundamental insights into methanol surface chemistry relevant to catalysis.