TY - JOUR
T1 - Towards Higher NH3 Faradaic Efficiency
T2 - Selective-Poisoning of HER Active Sites by Co-Feeding CO in NO Electroreduction**
AU - Li, Min
AU - Verkuil, Jarco
AU - Bunea, Sorin
AU - Kortlever, Ruud
AU - Urakawa, Atsushi
PY - 2023
Y1 - 2023
N2 - 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.
AB - 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.
KW - co-feeding CO
KW - direct ammonia synthesis
KW - electrochemical NO reduction
KW - hydrogen evolution suppression
KW - selective poisoning
UR - http://www.scopus.com/inward/record.url?scp=85168663876&partnerID=8YFLogxK
U2 - 10.1002/cssc.202300949
DO - 10.1002/cssc.202300949
M3 - Article
AN - SCOPUS:85168663876
SN - 1864-5631
VL - 16
JO - ChemSusChem
JF - ChemSusChem
IS - 22
M1 - e202300949
ER -