Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

A novel one-step method to synthesize copper nitrate hydroxide nanorings

With the purpose of searching for a convenient process to synthesize nanoparticles with special structure,a simple solid-state reaction in the presence of nonionic surfactant OP-10 at room temperature was adopted to prepare copper nitrate hydroxide(Cu_(2)(OH)_(3)NO_(3))nanorings with an average internal diameter of 250 nm and average wall thickness of 100 nm.The formation of Cu_(2)(OH)_(3)NO_(3) nanorings has a close relation with OP-10.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FESEM),thermogravimetric analysis(TGA)and X-ray diffractometry(XRD)were used to characterize the obtained nanorings.The UV-Vis spectrum shows that the optical property of Cu_(2)(OH)_(3)NO_(3) nanorings is similar to that of CuO or CuS.The synthesis method used here proves both simplicity and high efficiency.

Study on the mechanism of copper-ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal

Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method（SFM） was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.

Novel hybrids of Cu^(2+) ternary complexes of salicylidene-amino acid Schiff base with phenanthroline(or bipyridine) intercalated in Mg/Al-NO_3-layered double hydroxide

Four Cu2＋ complexes of salicylidene-amino acid Schiff base with 1,10-phenanthroline （Phen） or 2,2＇- bipyridine （Bipy） were successfully intercalated in interlayer galleries of Mg/AI-NO3-1ayered double hydroxide （LDH） by the swelling-restored method. The hybrids were characterized by elemental analysis, X-ray diffraction, FT-IR spectra, UV-vis DRS, TG-DTA and SEM observation. Good protection of the complexes by LDH in neutral and weak acidic solutions was revealed by UV spectra, cyclic voltammograms and luminescence spectra.

The effect of the amount of ammonia on the Cu^0/Cu^+ ratio of Cu/SiO_2 catalyst for the hydrogenation of dimethyl oxalate to ethylene glycol

The effect of the amount of precipitant ammonia on the Cu0/Cu＋ratio of Cu/Si O2 prepared by the deposition–precipitation method is investigated. Species at different preparation stages, resulted from the amount of ammonia used, are identified by the XRD and FTIR techniques. Chrysocolla together with either copper nitrate hydroxide or copper hydroxide coexist in the uncalcined catalysts. Upon calcination, the latter two species are converted to Cu O particles while chrysocolla remains. Following reduction, Cu O is transformed to metallic Cu and chrysocolla is converted to Cu2 O. The value of Cu0/Cu＋ratio can be evaluated using the peak areas in their TPR profiles. Hydrogenation of dimethyl oxalate（DMO） to ethylene glycol（EG） shows that the selectivity of EG depends on the Cu0/Cu＋ratio. Catalyst prepared with the addition of ammonia solution at n（NH3）/n（Cu2＋） = 0.9 for precipitation–deposition gains a more suitable Cu0/Cu＋ratio upon reduction and thus has a higher selectivity for EG.