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Journal ArticleDOI

Deciphering and Suppressing Over-Oxidized Nitrogen in Nickel-Catalyzed Urea Electrolysis

TLDR
In this paper, a nitrogen-fate network involving a NO2- -formation pathway via OH-assisted C-N cleavage and two N2 -formation pathways via intra- and intermolecular coupling was derived.
Abstract
Urea electrolysis is a prospective technology for simultaneous H2 production and nitrogen suppression in the process of water being used for energy production. Its sustainability is currently founded on innocuous N2 products; however, we discovered that prevalent nickel-based catalysts could generally over-oxidize urea into NO2- products with ≈80 % Faradaic efficiencies, posing potential secondary hazards to the environment. Trace amounts of over-oxidized NO3- and N2 O were also detected. Using 15 N isotopes and urea analogues, we derived a nitrogen-fate network involving a NO2- -formation pathway via OH- -assisted C-N cleavage and two N2 -formation pathways via intra- and intermolecular coupling. DFT calculations confirmed that C-N cleavage is energetically more favorable. Inspired by the mechanism, a polyaniline-coating strategy was developed to locally enrich urea for increasing N2 production by a factor of two. These findings provide complementary insights into the nitrogen fate in water-energy nexus systems.

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Regulating the tip effect on single-atom and cluster catalysts: forming reversible oxygen species with high efficiency in chlorine evolution reaction.

TL;DR: In this paper , it was shown that the oxidized sub-nano iridium clusters supported by titanium carbide exhibit much higher efficiency than the single-atom one, which demonstrates the significance of modifying the electronic interaction.
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Strategies for Designing More Efficient Electrocatalysts towards Urea Oxidation Reaction

TL;DR: The intrinsic sluggish kinetics of the urea oxidation reaction (UOR) is a pivotal half-reaction for urea assisted water splitting to produce hydrogen, direct urea fuel cells and electrochemical degradation of urea-containing wastewater as discussed by the authors.
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A review of hetero-structured Ni-based active catalysts for urea electrolysis

TL;DR: Urea electrooxidation has received considerable attention because of its tremendous practical application in environmental protection and energy regeneration as mentioned in this paper , and as an electrochemical reaction, the catalytic performance of urea oxidation is highly...
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Identification and manipulation of dynamic active site deficiency-induced competing reactions in electrocatalytic oxidation processes

TL;DR: A detrimental competition between the urea oxidation reaction (UOR) and oxygen evolution reaction is identified in this article , and strategies are proposed to alleviate such competition and boost the performance of the UOR and other organic compound oxidation reactions.
Journal ArticleDOI

Formation and Stabilization of NiOOH by Introducing α‐FeOOH in LDH: Composite Electrocatalyst for Oxygen Evolution and Urea Oxidation Reactions

TL;DR: In this article , a composite composed of α•FeOOH and LDH is well designed and successfully fabricated in hydrothermal treatment by adding extra Fe3+ resource, and stable NiOOH is obtained by the following electro-oxidation method.
References
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Journal ArticleDOI

Ni(OH)2 Nanoplates Grown on Graphene as Advanced Electrochemical Pseudocapacitor Materials

TL;DR: Ni(OH)2 nanocrystals grown on graphene sheets with various degrees of oxidation are investigated as electrochemical pseudocapacitor materials for potential energy storage applications in this paper, where they exhibit a high specific capacitance of ∼1335 F/g at a charge and discharge current density of 2.8 A/g and ∼953 F/m at 45.7 A/m with excellent cycling ability.
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Recent progress made in the mechanism comprehension and design of electrocatalysts for alkaline water splitting

TL;DR: In this paper, the authors describe the fundamentals of the hydrogen evolution reaction/oxygen evolution reaction (HER/OER) and construct efficient electrocatalysts based on the structure-activity relationship.
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Urea electrolysis: direct hydrogen production from urine

TL;DR: A new technology has been developed that accomplishes the direct conversion of urine and urea to pure hydrogen via electrochemical oxidation with an inexpensive nickel catalyst.
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Dramatic visible photocatalytic degradation performances due to synergetic effect of TiO2 with PANI.

TL;DR: The dramatic visible light photocatalytic activity was obtained for the degradation of Methylene Blue and Rhodamine B under visible light irradiation after TiO2 photocatallysts were modified with monolayer dispersed polyaniline (PANI) via a facile chemisorption approach.
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Treatment processes for source-separated urine.

TL;DR: A comprehensive review of current urine treatment processes and summarises the properties of collected urine shows clearly that a wide range of technical options is available to treat collected urine effectively, but that none of these single options can accomplish all seven purposes.
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