Atmospheric pressure electrochemical ammonia (NH3) synthesis is a promising alternative to the energy-intensive Haber-Bosch route. However, the industrial demand for ampere current density or gram-level ammonia yield for electrochemical ammonia synthesis remains a major challenge.
Based on this,Professor Yan Junmin, Shi Miaomiao, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Professor Zhong Haixia (co-corresponding author) and othersThe use of Cu-activated CO electrodes in bipolar membrane (BPM) assembly electrolyzers to produce NH3 at a high rate by NO2-reduction is reported, where BPM maintains ion equilibrium and electrolyte level.
Theoretical calculations show that Cu optimizes the adsorption behavior of NO2- and promotes the hydrogenation step at the CO site, so that NO2- can be reduced rapidly. The projected density of states (PDOS) diagram shows that CO has more electronic states near the Fermi level, indicating that *NO2 has strong chemical adsorption on its surface. The introduction of Cu atoms shifts the center of the D-band to the left, weakening the adsorption of NO2- at the CO site, which facilitates the subsequent hydrogenation step.
In this paper, the Gibbs free energy (δg) distribution of NO2-RR is further calculated. For Co, the potential-determining step (PDS) is *nh to *nh2 with g of 284 EV, which is due to the strong adsorption of *H on CO atoms which limits the subsequent hydrogenation of *NH, thereby impairing the performance of NO2-RR.
The introduction of Cu adjusted the strong adsorption energy of the CO site, so that PDS was transformed from *NO to *NOH, and the GPDS of CuCo and CuCO3O4 were 0., respectively15 and 214 ev。After Cu doping, the adjacent CO atoms are still able to adsorb enough *H to support the efficient hydrogenation process of the N species and improve the overall electrochemical activity.
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gram-level nh3 electrosynthesis via nox reduction on cu activated co electrode. angew. chem. int. ed.,, doi: 10.1002/anie.202315238.