Reaction-driven selective CO₂ hydrogenation to formic acid on Pd(111)

Area of Science:

• Catalysis and Surface Science
• Computational Chemistry
• Green Chemistry

Background:

• CO2 conversion to fuels and chemicals is crucial but challenging due to CO2's inertness.
• Palladium (Pd) catalysts are studied for CO2 hydrogenation, potentially yielding methanol or formic acid.
• Controlling selectivity in CO2 hydrogenation remains a significant hurdle.

Purpose of the Study:

• To investigate the selective production of formic acid via CO2 hydrogenation.
• To elucidate the role of surface hydrogen on Pd(111) in directing catalytic pathways.
• To understand the mechanism of selective formic acid formation using computational methods.

Main Methods:

• Combined Density Functional Theory (DFT) and Kinetic Monte Carlo (KMC) simulations.
• Modeling CO2 hydrogenation on a stable Pd(111) surface phase.
• Analysis of reaction pathways under conditions of full hydrogen coverage.

Main Results:

• Selective production of formic acid was achieved on hydrogen-covered Pd(111).
• CO2 activation proceeds via a carboxyl intermediate, differing from methanol-producing pathways.
• Surface hydrogen facilitates hydrogenation and stabilizes intermediates, promoting formic acid selectivity.

Conclusions:

• Full hydrogen coverage on Pd(111) steers CO2 hydrogenation towards selective formic acid production.
• Surface hydrogen plays a dual role: as a reactant reservoir and in creating active sites.
• Reactive surface environments are critical for tuning catalyst activity and selectivity in CO2 conversion.