Towards Higher NH3 Faradaic Efficiency

Selective-Poisoning of HER Active Sites by Co-Feeding CO in NO Electroreduction**

Journal Article (2023)
Authors

Min Li (ChemE/Catalysis Engineering)

Jarco Verkuil (Student TU Delft)

S. Bunea (ChemE/Catalysis Engineering)

Ruud Kortlever (TU Delft - Large Scale Energy Storage)

Atsushi Urakawa (ChemE/Catalysis Engineering)

Affiliation
ChemE/Catalysis Engineering
Copyright
© 2023 M. Li, Jarco Verkuil, S. Bunea, R. Kortlever, A. Urakawa
To reference this document use:
https://doi.org/10.1002/cssc.202300949
More Info
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Publication Year
2023
Language
English
Copyright
© 2023 M. Li, Jarco Verkuil, S. Bunea, R. Kortlever, A. Urakawa
Affiliation
ChemE/Catalysis Engineering
Issue number
22
Volume number
16
DOI:
https://doi.org/10.1002/cssc.202300949
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Abstract

Direct electroreduction of nitric oxide offers a promising avenue to produce valuable chemicals, such as ammonia, which is an essential chemical to produce fertilizers. Direct ammonia synthesis from NO in a polymer electrolyte membrane (PEM) electrolyzer is advantageous for its continuous operation and excellent mass transport characteristics. However, at a high current density, the faradaic efficiency of NO electroreduction reaction is limited by the competing hydrogen evolution reaction (HER). Herein, we report a CO-mediated selective poisoning strategy to enhance the faradaic efficiency (FE) towards ammonia by suppressing the HER. In the presence of only NO at the cathode, Pt/C and Pd/C catalysts showed a lower FE towards NH3 than to H2 due to the dominating HER. Cu/C catalyst showed a 78 % FE towards NH3 at 2.0 V due to the stronger binding affinity to NO* compared to H*. By co-feeding CO, the FE of Cu/C catalyst towards NH3 was improved by 12 %. More strikingly, for Pd/C, the FE towards NH3 was enhanced by 95 % with CO co-feeding, by effectively suppressing HER. This is attributed to the change of the favorable surface coverage resulting from the selective and competitive binding of CO* to H* binding sites, thereby improving NH3 selectivity.