TY - JOUR
T1 - Water flooding behavior in flow cells for ammonia production via electrocatalytic nitrogen reduction
AU - Pan, Zhefei
AU - Khalid, Farhan
AU - Tahir, Abdullah
AU - Esan, Oladapo Christopher
AU - Zhu, Jie
AU - Chen, Rong
AU - An, Liang
N1 - Funding Information:
This work was fully supported by a grant from the National Natural Science Foundation of China ( No. 52022003 ).
Publisher Copyright:
© 2021
PY - 2022/9
Y1 - 2022/9
N2 - The green production of ammonia, in an electrochemical flow cell under ambient conditions, is a promising way to replace the energy-intensive Haber-Bosch process. In the operation of this flow cell with an alkaline electrolyte, water is produced at the anode but also required as an essential reactant at the cathode for nitrogen reduction. Hence, water from the anode is expected to diffuse through the membrane to the cathode to compensate for the water needed for nitrogen reduction. Excessive water permeation, however, tends to increase the possibility of water flooding, which would not only create a large barrier for nitrogen delivery and availability, but also lead to severe hydrogen evolution as side reaction, and thus significantly lower the ammonia production rate and Faradaic efficiency. In this work, the water flooding phenomenon in flow cells for ammonia production via electrocatalytic nitrogen reduction is verified via the visualization approach and the electrochemical cell performance. In addition, the effects of the nitrogen flow rate, applied current density, and membrane thickness on the water crossover flux and ammonia production rate are comprehensively studied. The underlying mechanism of water transport through the membrane, including diffusion and electro-osmotic drag, is precisely examined and specified to provide more insight on water flooding behavior in the flow cell.
AB - The green production of ammonia, in an electrochemical flow cell under ambient conditions, is a promising way to replace the energy-intensive Haber-Bosch process. In the operation of this flow cell with an alkaline electrolyte, water is produced at the anode but also required as an essential reactant at the cathode for nitrogen reduction. Hence, water from the anode is expected to diffuse through the membrane to the cathode to compensate for the water needed for nitrogen reduction. Excessive water permeation, however, tends to increase the possibility of water flooding, which would not only create a large barrier for nitrogen delivery and availability, but also lead to severe hydrogen evolution as side reaction, and thus significantly lower the ammonia production rate and Faradaic efficiency. In this work, the water flooding phenomenon in flow cells for ammonia production via electrocatalytic nitrogen reduction is verified via the visualization approach and the electrochemical cell performance. In addition, the effects of the nitrogen flow rate, applied current density, and membrane thickness on the water crossover flux and ammonia production rate are comprehensively studied. The underlying mechanism of water transport through the membrane, including diffusion and electro-osmotic drag, is precisely examined and specified to provide more insight on water flooding behavior in the flow cell.
KW - Electrochemical ammonia production
KW - Flow cells
KW - Nitrogen reduction
KW - Operation conditions
KW - Water flooding
KW - Water transport
UR - http://www.scopus.com/inward/record.url?scp=85122688644&partnerID=8YFLogxK
U2 - 10.1016/j.fmre.2021.09.001
DO - 10.1016/j.fmre.2021.09.001
M3 - Journal article
AN - SCOPUS:85122688644
SN - 2667-3258
VL - 2
SP - 757
EP - 763
JO - Fundamental Research
JF - Fundamental Research
IS - 5
ER -