Efficient Electrocatalytic Synthesis of Ammonia from Water and Air in a Membrane‐Free Cell: Confining the Iron Oxide Catalyst to the Cathode

Liu, Xinye; Li, Fangfang; Peng, Ping; Licht, Gad; Licht, Stuart

doi:10.1002/ejic.201900667

Cited by 6 publications

(7 citation statements)

References 79 publications

(120 reference statements)

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“…The standard electrode potential (or reduction potential) of ferrous ions obtained from electron loss was 0.44 V. [20] Thus, as the iron electrodes were loaded with a potential over 0.44 V, the oxidation reaction could occur at the anode as follows (see middle images in Figure 1b): Fe − 2e − = Fe 2+ , where Fe 2+ ions were further oxidized by oxygen (from air) into Fe 3+ ions through the reaction of 4Fe 2+ + O 2 + 4H + = 4Fe 3+ + 2H 2 . [21] The cathode reaction did not generate metal ions, but giving rise to hydroxyl ions by following the chemical reaction: [22] Driven by the difference of potential, Fe 3+ ions migrated toward the cathode, and OH − shifted to the anode, resulting in the reaction of Fe 3+ + 3OH − = Fe(OH) 3 , which turned hydrogel into reddish-brown color, and elicited physical interaction with PAAm matrix (right image in Figure 1b, and more details will be discussed below).…”

Section: Resultsmentioning

confidence: 99%

“…[21] The cathode reaction did not generate metal ions, but giving rise to hydroxyl ions by following the chemical reaction: O 2 + 2H 2 O + 4e − = 4OH − . [22] Driven by the difference of potential, Fe 3+ ions migrated toward the cathode, and OH − shifted to the anode, resulting in the reaction of Fe 3+ + 3OH − = Fe(OH) 3 , which turned hydrogel into reddish-brown color, and elicited physical interaction with PAAm matrix (right image in Figure 1b, and more details will be discussed below).…”

Section: Resultsmentioning

confidence: 99%

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Electrochemistry‐Induced Improvements of Mechanical Strength, Self‐Healing, and Interfacial Adhesion of Hydrogels

Yan

Zhang

2021

Advanced Materials

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physical/chemical functionalization is capable of optimization of mechanical properties, [7] interfacial adhesion, [8] and self-healing ability of hydrogels. [9] These protocols normally introduced functional elements or structures that elicited physical/chemical interactions for the performance improvements of hydrogels. For example, polymeric nanoparticles from crystallization-driven self-assembly enabled mechanical improvements on hydrogel by physical hybridization with matrix. [10] Grafting silica nanoparticles to a double-network polymer also improved the hydrogel mechanical performances. [11] Construction of electrostatic interaction between carboxyl groups and various surfaces resulted in a catechol-chemistrybased hydrogel for the long-term adhesiveness. [12] Treatment by metal ions resulted in a hydrophobic surface that promoted formation of a water-resistant molecular bridge between the hydrogel surface and hydrophobic domains on the substrates, endowing the hydrogels prominent underwater-adhesion capability. [13] Similar adhesive hydrogel could also be achieved by dopamine-modified clay nanosheets. [14] An effective molecular structure design based on acid-ether hydrogen bonding and imine bonds was capable of accelerating hydrogel healing time to 30 min. [15] A dynamic borate bond in network enabled 100% cure of hydrogel in air. [16] Reversible metal-ligand coordination bonding interaction could also be used to construct self-healing hydrogel. [17] These protocols are efficient for the construction of functional hydrogels, yet still challenging to synchronously improve the mechanical strength, self-healing, and interfacial adhesion of a hydrogel, and especially, hard to endow the hydrogel with modular sensitivity to external pressure. Therefore, the development of a new class of protocol is still essential.Herein, we proposed an electrochemistry functionalization protocol, in which the functional improvements on hydrogels were achieved by the electrode reactions, and electrochemistrytriggered ionic and molecular migration. This protocol was capable of enabling the function improvements of the hydrogel in mechanical strength, interfacial adhesion, and self-healing. In the meantime, it allowed generation of various patterns on the hydrogel surface, and endowed the hydrogel modular sensitivity to external pressure. The functional improvements Hydrogels have demonstrated great potential in biomedical and engineering areas. To improve the physical performance, development of efficient physical/chemical protocols is essential. Herein, an electrochemistry functionalization strategy that is capable of enabling the functional improvements of hydrogel is reported. The electrochemistry functionalization is demonstrated on a hydrogel model of polyacrylamide (PAAm)@κ-carrageenan. The electrochemistry reaction generates metal ions (Fe 3+ ) that migrate and coordinate with the sulfate groups of κ-carrageenan resulting in the prominent function improvements. In comparison with untreated PAAm@κcarrageenan hydrogel, it c...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Electrochemistry‐Induced Improvements of Mechanical Strength, Self‐Healing, and Interfacial Adhesion of Hydrogels

Yan

Zhang

2021

Advanced Materials

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“…A further attempt at STEP-ammonia was launched by Licht and his co-workers. [66][67][68] They emphasized that nano-Fe 2 O 3 loaded on activated carbon (Fe 2 O 3 AC) achieves superior dispersion and effectively inhibits HER. The NH 3 yield rate of 8.27 Â 10 À9 mol s À1 cm À2 was obtained at a current density of 49 mA cm À2 .…”

Section: Electrode Engineeringmentioning

confidence: 99%

The state-of-the-art in the electroreduction of NO_x for the production of ammonia in aqueous and nonaqueous media at ambient conditions: a review

et al. 2023

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“…9 Confining the iron oxide catalyst to the cathode, to prevent the reoxidation of iron at the anode, can further improve ammonia production. 10 With respect to the promising results on the current efficiency and reaction rate in STEP ammonia, the durability and sustainability of the reaction system still need improvement to compete with the industrial process.…”

Section: Step For Carbon Neutral Productsmentioning

confidence: 99%

“…It was found that the Fe 2 O 3 /AC not only inhibits the hydrogen evolution reaction (HER) but also prevents the Fe 2 O 3 nanoparticles from aggregation, resulting in a high ammonia production rate of 8.27 × 10 –9 mol s –1 cm –2 at 250 °C with a current density of 49 mA/cm 2 . Confining the iron oxide catalyst to the cathode, to prevent the reoxidation of iron at the anode, can further improve ammonia production …”

Section: Step For Carbon Neutral Productsmentioning

confidence: 99%

Recent Advances in Solar Thermal Electrochemical Process (STEP) for Carbon Neutral Products and High Value Nanocarbons

Ren

Peng

et al. 2019

Acc. Chem. Res.

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Conspectus Climate change represents one of the most important environmental issues of our time. Due to high levels of anthropogenic CO2 emissions, atmospheric CO2 has for the first time ever exceeded 415 ppm and has increased from 315 ppm in 1950. An annual increase in atmospheric CO2 of ∼2 ppm is equal to a net increase of ∼15.6 billion tons of CO2. The combustion of fossil fuels for electricity and transportation is still the main reason accounting for the CO2 accumulation. On the top of that, fossil fuels are widely used in our modern industry for the productions of indispensable social staples. For instance, the millennia old thermal reduction of iron ore by charcoal or baked coal (3C + 2Fe2O3 → 4Fe + 3CO2) continues as the main method for the production of iron. The artificial fertilizer ammonia boosts the global population and is mainly produced from the Haber–Bosch process, in which hydrogen is generated via steam reforming of methane (CH4 + 2H2O → 4H2 + CO2). Sequestration and diminution of CO2 require the development of a portfolio of technologies on (1) efficient and long-term harvesting of renewable energy, that is, solar, not only for electricity but also directly as the energy force in vital chemical processes, wherever possible, (2) carbon-neutral processes to replace current industrial processes that emit vast amounts of CO2, such as iron and ammonia production, and (3) new, low-cost technologies for CO2 capture and conversion with particular interests in the exploration of CO2 as the feedstock for fuels or other valuable chemicals and materials. To this end, we conducted some studies on the sustainable synthesis of ammonia and iron with net-zero CO2 emissions and large-scale CO2 capture and conversion into fuels and high value nanocarbon products via electrolysis in molten salt(s) with the introduction of the Solar Thermal Electrochemical Process (STEP). In STEP, solar UV–visible energy is focused on a photovoltaic device that generates the electricity to drive the electrolysis, while concurrently the solar thermal energy is focused on a second system to generate heat for the electrolysis cell. The utilization of the full spectrum of sunlight in STEP results in a higher solar energy efficiency than other solar conversion processes. STEP has been applied to conduct (1) CO2-free ammonia synthesis from nitrogen and water with the aid of nano-Fe2O3 in a molten hydroxide electrolyte, (2) CO2-free production of iron via electrochemical reduction of iron ore in molten carbonate, (3) CO2 capture and conversion into nanostructured carbon products as well as fuels in molten or mixed molten electrolytes, and (4) organic electrosynthesis of benzoic acid from benzene without overoxidizing into CO2. In this Account, we highlight some recent achievements in these topics and propose that using STEP is a highly efficient strategy for saving energy and, consequently, the environment. STEP is an ideal tool that can theoretically be applied to all endothermic reactions.

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Efficient Electrocatalytic Synthesis of Ammonia from Water and Air in a Membrane‐Free Cell: Confining the Iron Oxide Catalyst to the Cathode

Abstract: This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.

Cited by 6 publications

References 79 publications

Electrochemistry‐Induced Improvements of Mechanical Strength, Self‐Healing, and Interfacial Adhesion of Hydrogels

Electrochemistry‐Induced Improvements of Mechanical Strength, Self‐Healing, and Interfacial Adhesion of Hydrogels

The state-of-the-art in the electroreduction of NO_x for the production of ammonia in aqueous and nonaqueous media at ambient conditions: a review

Recent Advances in Solar Thermal Electrochemical Process (STEP) for Carbon Neutral Products and High Value Nanocarbons

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Efficient Electrocatalytic Synthesis of Ammonia from Water and Air in a Membrane‐Free Cell: Confining the Iron Oxide Catalyst to the Cathode

Abstract: This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.

Cited by 6 publications

References 79 publications

Electrochemistry‐Induced Improvements of Mechanical Strength, Self‐Healing, and Interfacial Adhesion of Hydrogels

Electrochemistry‐Induced Improvements of Mechanical Strength, Self‐Healing, and Interfacial Adhesion of Hydrogels

The state-of-the-art in the electroreduction of NOx for the production of ammonia in aqueous and nonaqueous media at ambient conditions: a review

Recent Advances in Solar Thermal Electrochemical Process (STEP) for Carbon Neutral Products and High Value Nanocarbons

Contact Info

Product

Resources

About

The state-of-the-art in the electroreduction of NO_x for the production of ammonia in aqueous and nonaqueous media at ambient conditions: a review