Single Atom Pt-Stabilized Superoxo Species for Direct Electrocatalytic Ethylene Epoxidation

Area of Science:

• Electrochemistry
• Catalysis
• Green Chemistry

Background:

• Current industrial ethylene oxide (EO) production is energy-intensive and relies on non-renewable resources.
• Electrocatalytic ethylene epoxidation using water as an oxidant offers a sustainable alternative but faces challenges with activity and selectivity due to overoxidation.
• Developing efficient catalysts is crucial for advancing low-carbon chemical manufacturing.

Purpose of the Study:

• To design and synthesize a novel catalyst for highly selective electrocatalytic ethylene epoxidation.
• To investigate the mechanism of reactive oxygen species (ROS) generation and their role in ethylene oxidation.
• To demonstrate the performance and scalability of the developed catalyst in a membrane electrode assembly electrolyzer.

Main Methods:

• Synthesis of Palladium Oxide (PdO) supported Platinum (Pt) single-atom catalyst.
• Electrocatalytic testing in a zero-gap membrane electrode assembly electrolyzer.
• In situ spectroscopic characterizations (e.g., X-ray spectroscopy) and theoretical calculations (e.g., Density Functional Theory).
• Scale-up demonstration using a 100 cm² electrolyzer.

Main Results:

• The PdO supported Pt single-atom catalyst efficiently generates superoxo species, acting as key ROS for selective ethylene epoxidation.
• Achieved a partial current density of 71 mA cm⁻² at a low cell voltage of 2.6 V.
• Demonstrated a scale-up production rate of 6.4 g h⁻¹ using a 100 cm² electrolyzer at 15 A.
• Elucidated the synergistic effect between Pt single atoms, ClO₄⁻ anions, and the PdO support in accelerating ethylene epoxidation.

Conclusions:

• The developed PdO supported Pt single-atom catalyst enables efficient and selective electrosynthesis of ethylene oxide from ethylene using water as a green oxidant.
• Generating and stabilizing specific ROS, like superoxo species, is critical for achieving high selectivity in organic molecule oxidation.
• This approach represents a significant advancement towards sustainable, low-carbon industrial chemical production.