Oxygen-containing and amino groups functionalized polymeric carbon nitride atomically-thin porous nanosheets with hydrophilic surfaces and strong Lewis basicity are designed and synthesized for enhanced photocatalytic H2evolution.
Electrochemical synthesis of urea provides a sustainable strategy that can be easily incorporated into currently distributed renewable energy systems. The main challenge that hindered the advancement of this technique lies in developing advanced electrocatalytic processes to utilize abundant and low-cost inorganic carbon and nitrogen sources for highly productive urea generation. Herein, we report an electrocatalytic reaction that converts carbon dioxide (CO 2 ) and nitric oxide (NO) into urea, with water as the hydrogen source, under ambient conditions. The yield rate and Faradaic efficiency of urea reach 15.13 mmol g −1 h −1 and 11.26% at a current density of 40 mA cm −2 under optimized conditions. The critical intermediates of *CO and *NH 2 for urea generation are obtained via the co-reduction of CO 2 and NO and then continuously interconnect to form the C−N bond. A preliminary techno-economic study is performed to discuss the practical application potential of this strategy for urea production.
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.
Electrochemical
reduction of carbon dioxide (CO2) to
fuels and value-added chemicals provides an intriguing approach to
realizing the artificial carbon cycle. The development of low-cost
electrocatalysts with high activity, selectivity, and stability for
CO2 reduction is of great significance but still a big
challenge. Herein, we present a dual-functionalization strategy to
synergistically active polymeric carbon nitride (PCN) for CO2 electroreduction by modifying hydroxyl and amino groups on the surface.
Compared with unmodified PCN, a 17.1-fold enhancement for CO yield
rate is achieved. The optimized ratio of CO/H2 is 0.67,
which is in the range for Fischer–Tropsch reactions (0.25–3.34).
The experiments and theory calculations propose that the superficial
hydroxyl and amino groups both serve as active sites for synergetic
activation of CO2. This work may open an avenue for designing
other metal-free electrocatalysts for CO2 conversion.
Electrochemical conversion of abundant carbon- and nitrogen-containing small molecules into high-valued organonitrogen compounds is alluring to reducing current dependence on fossil energy. Here we report a single-cell electrochemical oxidation approach to transform methanol and ammonia into formamide under ambient conditions over Pt electrocatalyst that provides 74.26% selectivity from methanol to formamide and a Faradaic efficiency of 40.39% at 100 mA cm−2 current density, gaining an economic advantage over conventional manufacturing based on techno-economic analysis. A 46-h continuous test performed in the flow cell shows no performance decay. The combined results of in situ experiments and theoretical simulations unveil the C–N bond formation mechanism via nucleophilic attack of NH3 on an aldehyde-like intermediate derived from methanol electrooxidation. This work offers a way to synthesize formamide via C–N coupling and can be extended to substantially synthesize other value-added organonitrogen chemicals (e.g., acetamide, propenamide, formyl methylamine).
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