Oxide-Derived Core–Shell Cu@Zn Nanowires for Urea Electrosynthesis from Carbon Dioxide and Nitrate in Water

Abstract

Urea electrosynthesis provides an intriguing strategy to improve upon the conventional urea manufacturing technique, which is associated with high energy requirements and environmental pollution. However, the electrochemical coupling of NO 3 − and CO 2 in H 2 O to prepare urea under ambient conditions is still a major challenge. Herein, self-supported core−shell Cu@Zn nanowires are constructed through an electroreduction method and exhibit superior performance toward urea electrosynthesis via CO 2 and NO 3 − contaminants as feedstocks. Both 1 H NMR spectra and liquid chromatography identify urea production. The optimized urea yield rate and Faradaic efficiency over Cu@Zn can reach 7.29 μmol cm −2 h −1 and 9.28% at −1.02 V vs RHE, respectively. The reaction pathway is revealed based on the intermediates detected through in situ attenuated total reflection Fourier transform infrared spectroscopy and online differential electrochemical mass spectrometry. The combined results of theoretical calculations and experiments prove that the electron transfer from the Zn shell to the Cu core can not only facilitate the formation of *CO and *NH 2 intermediates but also promote the coupling of these intermediates to form C−N bonds, leading to a high faradaic efficiency and yield of the urea product.

High-efficiency electrosynthesis of urea over bacterial cellulose regulated Pd–Cu bimetallic catalyst

“…[16][17][18][19][20][21][22][23][24][25][26][27][28] In comparion with N2 reactant, the superiorities of NO3 − and NO2 − as the reactants are high solubility in aqueous solution, lower dissociation energy of N=O bond (204 KJ mol −1 ), which enable more efficient C−N coupling reaction for urea production. [16][17][18][19][20][21][22][23][24][25][26][27][28] Besides of this, development of high-efficiency electrocatalysts is also critically important for urea synthesis. To date, precious and non-precious metals based electrocatalysts have been fabricated and investigated for electrocatalytic coupling of NO3 − and NO2 − (or NO) and CO2 to efficiently synthesize urea at ambient conditions, exhibiting high electrocatalytic activities.…”

“…To date, precious and non-precious metals based electrocatalysts have been fabricated and investigated for electrocatalytic coupling of NO3 − and NO2 − (or NO) and CO2 to efficiently synthesize urea at ambient conditions, exhibiting high electrocatalytic activities. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] In terms to catalytic mechanism research, Zhang et al reported that the formation of *CO and *NH2 intermediates through the adsorption and activation of CO2 and NO on Zn nanobelts catalyst is critically important for subsequent C−N coupling synthesis of urea with a yield rate of 15.13 mmol h −1 g −1 and a faradaic efficiency of 11.26% at ~40 mA cm −2 . 29 Meanwhile, Zhang et al synthesized urea by coupling CO2 with NO2 − on oxygen vacancy-rich ZnO porous nanosheets with a yield rate of 16.56 μmol h −1 and a faradaic efficiency of 23.26% at −0.79 V (vs. RHE).…”

“…9,10,30 To solve these issues caused by the N 2 precursor, nitrate (NO 3 À ) and nitrite (NO 2 À ) in aqueous electrolytes have been investigated as the nitrogen sources coupling with CO 2 for electrocatalytic synthesis of urea under ambient conditions. [16][17][18][19][20][21][22][23][24][25][26][27][28] In comparison with the N 2 reactant, the superiorities of NO 3 À and NO 2 À as the reactants are their high solubility in aqueous solution and the lower dissociation energy of the NQO bond (204 kJ mol À1 ), which enable more efficient C-N coupling reaction for urea production. [16][17][18][19][20][21][22][23][24][25][26][27][28] Besides this, the development of high-efficiency electrocatalysts is also critically important for urea synthesis.…”

“…and CO 2 to efficiently synthesize urea under ambient conditions, exhibiting high electrocatalytic activities. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] exposed {100} facets and InOOH with oxygen vacancies. 17,18 Recently, Rose Amal and co-workers reported a single-atom electrocatalyst with Cu-N 4 sites to couple CO 2 and NO 3 À with a urea yield rate of 4.3 mmol s À1 cm À2 and a faradaic efficiency (FE) of 28% at À0.9 V (vs. RHE).…”

Emerging p-Block-Element-Based Electrocatalysts for Sustainable Nitrogen Conversion

“…Up to now, transition metal (TM)-based materials have represented the state-of-the-art electrocatalysts toward the abovementioned nitrogen conversion reactions. − Despite the promising catalytic activities displayed by the TM-based materials, a limitation exists in the competition with the hydrogen evolution reaction (HER) because the d electrons prefer to participate in the formation of metal–H bonds . Recent advances demonstrate that p-block-element-based electrocatalysts provide an intriguing picture for nitrogen conversion reactions.…”