Te-Doped Pd Nanocrystal for Electrochemical Urea Production by Efficiently Coupling Carbon Dioxide Reduction with Nitrite Reduction

Abstract

The renewable electricity-driven reduction of carbon dioxide (CO 2 RR) is a promising technology for carbon utilization. However, it is still a challenge to broaden the application of CO 2 RR. Herein, we report a Te-doped Pd nanocrystals (Te−Pd NCs) for promoting urea synthesis by coupling CO 2 RR with electrochemical reduction of nitrite. The electrochemical synthesis of urea has been achieved with nearly 12.2% Faraday efficiency (FE) and 88.7% N atom efficiency (NE) at −1.1 V versus reversible hydrogen electrode (vs RHE), much higher than those of pure Pd NCs (4.2% FE and 21.8% NE). Significantly, an FE of ∼10.2% and an NE of ∼82.3% for urea solution production via an optimized flow cell system have been realized, where a solution with up to 0.95 wt % of urea has been obtained. Mechanistic insights show that Te-doping not only optimizes the CO 2 / CO adsorption but also promotes NH 3 production, fully meeting the requirements of urea synthesis.

AuCu nanofibers for electrosynthesis of urea from carbon dioxide and nitrite

“…The generated urea was decomposed into NH 3 by urease. 23,25 The absorption intensity of NH 3 converted from urea was measured by UV-Vis spectrophotometry, and the concentration was further determined from the calibration curve (Fig. S14).…”

“…Compared with N 2 , the high solubility of NO 2 − in water and its low activation energy barrier make the utilization of NO 2 − as a nitrogen source for electrochemical reduction reaction coupled with CO 2 RR to produce urea is more attractive. 23 For instance, Zhang and coauthors synthesized urea by coupling CO 2 RR with NO 2 − reduction reaction (NO 2 − RR) on oxygen vacancyrich ZnO porous nanosheets. 24 However, this strategy has parallel CO 2 RR and the NO 2 − RR, which will generate complex product distribution, thus reducing the FE of the urea and increasing the di culty of separating urea from the product.…”

Unveiling Electrochemical Urea Synthesis by Co‐Activation of CO2 and N2 with Mott–Schottky Heterostructure Catalysts

“…[6] . Compared with the conventional thermal catalytic and other hydrogenation processes, the utilization of the electrochemical approach exhibits great advantages in atom and energy economies [7] . It thus motivates researchers to construct an electrochemical C−N bond coupling system by directly using CO 2 and amine derivatives/nitrogen sources (nitrate, nitrite, NO, and even N 2 ) as feedstock [8] …”

“…However, the related catalytic activity and selectivity for electrochemical urea synthesis are still extremely low. The main challenges can be ascribed as i) extraordinarily weak chemical adsorption of inert CO 2 /N 2 on the catalysts surface; [11] ii) the dissociation of highly stable C=O bond and N≡N bond requires high overpotential; [5c, 12] iii) the parallel CO 2 /N 2 reduction reactions strongly competes with the desired C‐N coupling reaction for urea synthesis and further results in the complex product distribution [7] …”

Electrosynthesis of Green Urea by co-reduction of N2 and CO2 Using Dual Active Sites of Copper Phthalocyanine Nanotube

“…On the other hand, electrochemical urea synthesis by the co-reduction of N 2 and CO 2 (N 2 + CO 2 + 6H + + 6e -→ CO (NH 2 ) 2 + H 2 O) using efficient electrocatalyst in water medium under ambient conditions would be an alternative way in the upcoming days. Chen et al [14] [14,[17][18][19]. And finally, the suppression of hydrogen evolution reaction (HER), choice of electrolyte and catalyst are very crucial for electrochemical urea synthesis [14].…”