In Situ Raman Spectroscopic Insight of Hydrogen Spillover in Electrocatalytic Hydrogenation

Area of Science:

• Materials Science
• Electrochemistry
• Surface Science

Background:

• Adsorbed hydrogen species (*H) are crucial for electrochemical hydrogenation.
• Monitoring hydrogen spillover in situ is challenging due to coupled active sites and complex reaction environments.

Purpose of the Study:

• To achieve spectroscopic visualization of hydrogen spillover under electrochemical conditions.
• To investigate the facet-dependence and potential-tunability of hydrogen spillover.
• To enhance catalytic performance by leveraging the hydrogen spillover effect.

Main Methods:

• Utilized single-atom Ru-doped Cu as a model catalyst.
• Employed in situ surface-enhanced Raman spectroscopy (SERS) for spectroscopic visualization.
• Used para-nitrothiophenol as a probe molecule to determine spillover distance.

Main Results:

• Successfully visualized hydrogen spillover under electrochemical conditions.
• Demonstrated that hydrogen spillover distance is facet-dependent (Cu(111) > Cu(100)).
• Showed that spillover distance is tunable with applied potentials, increasing from 0.8 to 2.6 nm with negative potential shifts.
• Increased hydrogen coverage via spillover altered the rate-determining step in nitrate electroreduction, enhancing performance.

Conclusions:

• In situ SERS provides a powerful tool for visualizing and understanding electrochemical hydrogen spillover.
• Facet engineering and potential control are effective strategies for manipulating hydrogen spillover.
• Optimizing hydrogen spillover significantly enhances electrocatalytic hydrogenation performance, as demonstrated in nitrate electroreduction.