Mechanistic Insights into Nitroarene Hydrogenation Dynamics on Pt(111) via In Situ Tip-Enhanced Raman Spectroscopy

Area of Science:

• Heterogeneous Catalysis
• Surface Science
• Spectroscopy

Background:

• Understanding nitroarene hydrogenation on platinum (Pt) at the molecular level is crucial but limited by traditional methods.
• Existing studies often use ex situ measurements or isolated simulations, hindering real-time mechanistic insights.

Purpose of the Study:

• To elucidate the molecular dynamics of nitroarene hydrogenation on Pt(111) using a novel combined in situ technique.
• To track the real-time transformation of chloronitrothiophenol (CNTP) to chloroaminothiophenol (CATP) on a single plasmonic junction.

Main Methods:

• Utilized in situ tip-enhanced Raman spectroscopy (TERS) to monitor reactions at the nanoscale.
• Employed density functional theory (DFT) modeling to calculate reaction energetics and map mechanistic pathways.
• Integrated TERS and DFT for comprehensive operando studies of heterogeneous catalysis.

Main Results:

• In situ TERS captured the CNTP to CATP transformation with a characteristic time scale of approximately 6 seconds.
• DFT revealed that CNTP desorption slows with increasing surface coverage and identified the second hydrogen addition as the rate-determining step (0.83 eV barrier).
• The combined experimental and computational approach yielded mechanistic insights consistent with observed reaction timescales.

Conclusions:

• Demonstrated the power of integrating in situ TERS with DFT for nanoscale mechanistic studies of catalytic processes.
• Advanced the molecular-level understanding of nitroarene hydrogenation on Pt(111).
• Established a novel methodology for real-time operando analysis of heterogeneous catalysis.