Molecular Self-Assembly in Conductive Covalent Networks for Selective Nitrate Electroreduction to Ammonia

Sun, Feiqing; Gao, Yifan; Li, Mengjie; Wen, Yingke; Fang, Yanjie; Meyer, Thomas J.; Shan, Bing

doi:10.1021/jacs.3c07320

Cited by 30 publications

(16 citation statements)

References 47 publications

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“…−0.86 V vs RHE), although we note that the bare coinage metal electrodes have high background activity for NO 3 RR even without Co(cyclam), − and Co(cyclam) shows almost no activity for NO 3 – reduction to NH 3 at Hg electrodes. , Nonetheless, the p-TPTCrCl 3 system is one of the most active molecular catalyst systems reported for selective reduction of aqueous NO 3 – to NH 4 + with comparable activity and selectivity to recently reported state-of-the-art solid-state catalyst systems (Figure and Table S8). − …”

Section: Resultsmentioning

confidence: 99%

Selective Reduction of Aqueous Nitrate to Ammonium with an Electropolymerized Chromium Molecular Catalyst

Askari,

Kallick,

McCrory

2024

J. Am. Chem. Soc.

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Nitrate (NO 3 − ) is a common nitrogen-containing contaminant in agricultural, industrial, and low-level nuclear wastewater that causes significant environmental damage. In this work, we report a bioinspired Cr-based molecular catalyst incorporated into a redox polymer that selectively and efficiently reduces aqueous NO 3 − to ammonium (NH 4 + ), a desirable value-added fertilizer component and industrial precursor, at rates of ∼0.36 mmol NH 4 + mg cat −1 h −1 with >90% Faradaic efficiency for NH 4 + . The NO 3 − reduction reaction occurs through a cascade catalysis mechanism involving the stepwise reduction of NO 3 − to NH 4 + via observed NO 2 − and NH 2 OH intermediates. To our knowledge, this is one of the first examples of a molecular catalyst, homogeneous or heterogenized, that is reported to reduce aqueous NO 3− to NH 4 + with rates and Faradaic efficiencies comparable to those of state-of-the-art solid-state electrocatalysts. This work highlights a promising and previously unexplored area of electrocatalyst research using polymer−catalyst composites containing complexes with oxophilic transition metal active sites for electrochemical nitrate remediation with nutrient recovery.

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Section: Resultsmentioning

confidence: 99%

Selective Reduction of Aqueous Nitrate to Ammonium with an Electropolymerized Chromium Molecular Catalyst

Askari,

Kallick,

McCrory

2024

J. Am. Chem. Soc.

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“…It has been mentioned in the above chapter that the physicochemical properties of MXenes can be greatly changed by simply regulating the functional groups on the surface of MXenes. Interestingly, hydrophilicity and hydrophobicity can be changed by adjusting the type and proportion of surface functional groups of MXenes [34] . On the one hand, the high hydrophilicity of MXenes can enhance the solid-liquid interface between the catalysts and the electrolyte, which is conducive to promoting the diffusion of NO 3 -.…”

Section: Controlled Surface Chemistrymentioning

confidence: 99%

Emerging MXene-based electrocatalysts for efficient nitrate reduction to ammonia: recent advance, challenges, and prospects

Cui,

Li,

Peng

et al. 2024

Energy Mater

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Ammonia (NH3) plays an irreplaceable role in traditional agriculture and emerging renewable energy. Its preparation in industry mainly relies on the energy-intensive Haber-Bosch process, which is associated with high energy consumption and large CO2 emissions. Recently, the nitrate reduction reaction (NO3-RR) driven by renewable energy has received extensive attention. This reaction can efficiently synthesize NH3 with water as a hydrogen source and NO3- as a nitrogen source under mild conditions, which is conducive to reducing energy consumption and promoting the carbon cycle. It is well known that the properties of electrocatalysts determine the performance of NO3-RR. As an emerging two-dimensional material, MXenes (transition metal carbides/nitrides/carbon nitrides) possess excellent electrical conductivity, large specific surface area and controllable surface functional groups, which shows great application potential in the field of NO3-RR. Herein, this review summarized the structure, properties and synthesis strategies of MXenes to elucidate the possibilities from foundation to application. Then, the latest research progress in applying MXene-based electrocatalysts to NO3-RR was summarized and the applicability of different NH3 detection methods was analyzed. Finally, the present challenges and future prospects of NO3-RR were presented. This review aimed to provide thoughtful insights into the rational design of MXene-based electrocatalysts for sustainable NH3 synthesis.

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“…Overuse of nitrogen-based fertilizers and sewage discharge lead to excessive nitrate levels in the environment, severely polluting groundwater. − Among the reported treatment technologies, electrocatalytic nitrate reduction to ammonia (NRA) is alluring owing to the utilization of water as a hydrogen source and electrons as reductants. − During the past years, a series of materials have been adopted as NRA electrocatalysts. − Among them, cobalt-based electrocatalysts have attracted great attention due to their low cost and excellent NRA performances across a wide potential range. ,, Although great progress has been made, the reaction mechanism as well as veritable active species for NRA over cobalt-based electrocatalysts are still full of controversy. Taking CoP as an example, many reports proved the formation of Co(OH) 2 on the surface after NRA.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Reaction Mechanism of Nitrate Reduction to Ammonia Over Cobalt-Based Electrocatalysts

Yang,

Han,

Cheng

et al. 2024

J. Am. Chem. Soc.

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Electrocatalytic reduction of nitrate to ammonia (NRA) has emerged as an alternative strategy for sewage treatment and ammonia generation. Despite excellent performances having been achieved over cobalt-based electrocatalysts, the reaction mechanism as well as veritable active species across a wide potential range are still full of controversy. Here, we adopt CoP, Co, and Co 3 O 4 as model materials to solve these issues. CoP evolves into a core@shell structured CoP@Co before NRA. For CoP@Co and Co catalysts, a three-step relay mechanism is carried out over superficial dynamical Co δ+ active species under low overpotential, while a continuous hydrogenation mechanism from nitrate to ammonia is unveiled over superficial Co species under high overpotential. In comparison, Co 3 O 4 species are stable and steadily catalyze nitrate hydrogenation to ammonia across a wide potential range. As a result, CoP@Co and Co exhibit much higher NRA activity than Co 3 O 4 especially under a low overpotential. Moreover, the NRA performance of CoP@Co is higher than Co although they experience the same reaction mechanism. A series of characterizations clarify the reason for performance enhancement highlighting that CoP core donates abundant electrons to superficial active species, leading to the generation of more active hydrogen for the reduction of nitrogen-containing intermediates.

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Molecular Self-Assembly in Conductive Covalent Networks for Selective Nitrate Electroreduction to Ammonia

Cited by 30 publications

References 47 publications

Selective Reduction of Aqueous Nitrate to Ammonium with an Electropolymerized Chromium Molecular Catalyst

Selective Reduction of Aqueous Nitrate to Ammonium with an Electropolymerized Chromium Molecular Catalyst

Emerging MXene-based electrocatalysts for efficient nitrate reduction to ammonia: recent advance, challenges, and prospects

Unveiling the Reaction Mechanism of Nitrate Reduction to Ammonia Over Cobalt-Based Electrocatalysts

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