Modulating Metal‐Nitrogen Coupling in Anti‐Perovskite Nitride via Cation Doping for Efficient Reduction of Nitrate to Ammonia

Abstract

The complexes of metal center and nitrogen ligands are the most representative systems for catalyzing hydrogenation reactions in small molecule conversion. Developing heterogeneous catalysts with similar active metal‐nitrogen functional centers, nevertheless, still remains challenging. In this work, we demonstrate that the metal‐nitrogen coupling in anti‐perovskite Co4N can be effective modulated by Cu doping to form Co3CuN, leading to strongly promoted hydrogenation process during electrochemical reduction of nitrate (NO3−RR) to ammonia. The combination of advanced spectroscopic techniques and density functional theory calculations reveal that Cu dopants strengthen the Co−N bond and upshifted the metal d‐band towards the Fermi level, promoting the adsorption of NO3− and *H and facilitating the transition from *NO2/*NO to *NO2H/*NOH. Consequently, the Co3CuN delivers noticeably better NO3−RR activity than the pristine Co4N, with optimal Faradaic efficiency of 97 % and ammonia yield of 455.3 mmol h−1 cm−2 at −0.3 V vs. RHE. This work provides an effective strategy for developing high‐performance heterogeneous catalyst for electrochemical synthesis.

Core–Shell Engineering Boosted Active Hydrogen Generation in Cu2–xS/MoS2 Quantum Dots for Efficient Electrocatalytic Nitrate Reduction to Ammonia

“…Therefore, an appropriate intensity of the HER can avoid a strong HER and retain sufficient H ads , which is another critical consideration for the hydrogenation reaction of nitrogen intermediates. According to adsorption configurations of different catalysts (Figure S5), Figure f shows the Gibbs free energy of −2.4209, 1.3751, and −0.1374 eV for Cu 2– x S/MoS 2 , Cu 2– x S, and MoS 2 during the HER process, respectively, which demonstrates that MoS 2 is mainly used for activation of water to generate active hydrogen with near-zero free energy and the Cu 2– x S/MoS 2 interface has the strongest H* retention and adsorption ability . The change in the Gibbs free energy is shown in Table S4.…”

Unveiling the Reaction Mechanism of Nitrate Reduction to Ammonia Over Cobalt-Based Electrocatalysts

“…This result is also confirmed by XPS where the binding energy of Co 0 peak in CoP@Co is 777.82 eV, lower than that of Co (777.94 eV) (Figure b) . According to density functional theory (DFT) calculations, CoP@Co forms *H more easily and the as-generated *H is more difficult to form H 2 than Co, suggesting that the surface of CoP@Co is more prone to *H accumulation (Figure c). , To verify the existence of *H, the electrochemical quasi in situ electron paramagnetic resonance (EPR) is studied . The EPR spectra of CoP@Co and Co (in 1.0 M KOH solution at −0.2 V vs RHE) are recorded using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the H-radical trapping reagent (Figure d).…”

“…With the introduction of CoP, the energy barrier in the rate-limiting step (Co: *N to *NH, 3.02 eV; CoP@Co: *NO to *NOH, 0.45 eV) changes, which is consistent with the ultralow overpotential of CoP@Co for NRA. To be specific, a more negative value of projected crystal orbital hamilton population (−pCOHP) indicates that the intermediate *N is in a more stable state on CoP@Co, which is favorable for the subsequent hydrogenation to NH 3 …”

Nanostructured Conductive Metal–Organic Frameworks: Synthesis and Applications

“…Electroreduction of NO 3 − to ammonia (NRA) represents a prospective route for both high‐value‐added NH 3 synthesis and wastewater treatment, where the design of high‐efficiency electrocatalysts to drive the complex electron–proton‐coupled process is crucial. [ 99,100 ] Very recently, two kinds of nc ‐MOFs, Ni‐HHTP (denoted as Ni‐O 4 ‐CCP) and Ni‐HITP (Ni‐N 4 ‐CCP) were applied as electrocatalysts to investigate the impact of coordination environment on NRA performance. [ 101 ] The electrochemical results showed that Ni‐O 4 ‐CCP exhibited a higher NH 3 yield rate of 1.83 mmol h −1 mg −1 ( Figure a) and Faraday efficiency of 94.7% (Figure 18b).…”