scholarly journals Catalyst-free, highly selective synthesis of ammonia from nitrogen and water by a plasma electrolytic system

2019 ◽  
Vol 5 (1) ◽  
pp. eaat5778 ◽  
Author(s):  
Ryan Hawtof ◽  
Souvik Ghosh ◽  
Evan Guarr ◽  
Cheyan Xu ◽  
R. Mohan Sankaran ◽  
...  
Keyword(s):  
Material Surface ◽  
Ambient Conditions ◽  
Radical Intermediate ◽  
Solvated Electrons ◽  
Reaction Conditions ◽  
Faradaic Efficiency ◽  
Catalyst Free ◽  
Hydrogen Radical ◽  
Plasma Electrolytic ◽  
Plasma Electrode

There is a growing need for scalable ammonia synthesis at ambient conditions that relies on renewable sources of energy and feedstocks to replace the Haber-Bosch process. Electrically driven approaches are an ideal strategy for the reduction of nitrogen to ammonia but, to date, have suffered from low selectivity associated with the catalyst. Here, we present a hybrid electrolytic system characterized by a gaseous plasma electrode that facilitates the study of ammonia formation in the absence of any material surface. We find record-high faradaic efficiency (up to 100%) for ammonia from nitrogen and water at atmospheric pressure and temperature with this system. Ammonia measurements under varying reaction conditions in combination with scavengers reveal that the unprecedented selectivity is achieved by solvated electrons produced at the plasma-water interface, which react favorably with protons to produce the key hydrogen radical intermediate. Our results demonstrate that limitations in selectivity can be circumvented by using catalyst-free solvated electron chemistry. In the absence of adsorption steps, the importance of controlling proton concentration and transport is also revealed.

Novel One-pot Synthesis of Pyranocarbazole Derivatives via an Isocyanide-based Three-component Reaction

2020 ◽  
Vol 17 ◽  
Author(s):  
Visarapu Malathi ◽  
Pedavenkatagari Narayana Reddy ◽  
Pannala Padmaja
Keyword(s):  
Efficient Method ◽  
Atom Economy ◽  
Reaction Conditions ◽  
One Pot ◽  
Catalyst Free ◽  
One Pot Synthesis ◽  
Three Component Reaction ◽  
High Yields

Abstract:: An efficient method has been developed for the synthesis of new pyrano[3,2-c] and pyrano[3,2-a]carbazole de-rivatives via a three component reaction of 4-hydroxycarbazole or 2-hydroxycarbazole, isocyanides, and dialkylacetylenedi-carboxylates. Noteworthy features of this protocol include mild reaction conditions, catalyst-free, high atom-economy and high yields.

Visible-light-initiated Catalyst-free Oxidative Cleavage of Triaryl-Substituted Alkenes C=C Bonds under Ambient Conditions

2021 ◽  
Author(s):  
Wenjing Li ◽  
Shun Li ◽  
Lihua Luo ◽  
Yichen Ge ◽  
Jiaqi Xu ◽  
...  
Keyword(s):  
Visible Light ◽  
Room Temperature ◽  
Ambient Air ◽  
Oxidative Cleavage ◽  
Ambient Conditions ◽  
Blue Led ◽  
Catalyst Free

The catalyst-free oxidative cleavage of (Z)-triaryl-substituted alkenes bearing pyridyl motif with ambient air under irradiation of blue LED at room temperature has been developed. The reaction was facile and scalable,...

scholarly journals Synthesis of Valeric Acid by Selective Electrocatalytic Hydrogenation of Biomass-Derived Levulinic Acid

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 692
Author(s):  
Yan Du ◽  
Xiao Chen ◽  
Ji Qi ◽  
Pan Wang ◽  
Changhai Liang
Keyword(s):  
Levulinic Acid ◽  
Active Sites ◽  
Valeric Acid ◽  
Future Research ◽  
Adsorbed Hydrogen ◽  
Electrocatalytic Hydrogenation ◽  
Ambient Conditions ◽  
Metallic Lead ◽  
Faradaic Efficiency ◽  
Lead Electrode

The electrocatalytic hydrogenation (ECH) of biomass-derived levulinic acid (LA) is a promising strategy to synthetize fine chemicals under ambient conditions by replacing the thermocatalytic hydrogenation at high temperature and high pressure. Herein, various metallic electrodes were investigated in the ECH of LA in a H-type divided cell. The effects of potential, electrolyte concentration, reactant concentration, and temperature on catalytic performance and Faradaic efficiency were systematically explored. The high conversion of LA (93%) and excellent “apparent” selectivity to valeric acid (VA) (94%) with a Faradaic efficiency of 46% can be achieved over a metallic lead electrode in 0.5 M H2SO4 electrolyte containing 0.2 M LA at an applied voltage of −1.8 V (vs. Ag/AgCl) for 4 h. The combination of adsorbed LA and adsorbed hydrogen (Hads) on the surface of the metallic lead electrode is key to the formation of VA. Interestingly, the reaction performance did not change significantly after eight cycles, while the surface of the metallic lead cathode became rough, which may expose more active sites for the ECH of LA to VA. However, there was some degree of corrosion for the metallic lead cathode in this strong acid environment. Therefore, it is necessary to improve the leaching-resistance of the cathode for the ECH of LA in future research.

scholarly journals Enabling the electrocatalytic fixation of N2 to NH3 by C-doped TiO2 nanoparticles under ambient conditions

2019 ◽  
Vol 1 (3) ◽  
pp. 961-964 ◽  
Author(s):  
Kun Jia ◽  
Yuan Wang ◽  
Qi Pan ◽  
Benhe Zhong ◽  
Yonglan Luo ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Ambient Conditions ◽  
Faradaic Efficiency ◽  
Doped Tio2

C-TiO2 is efficient for electrochemical N2 fixation to NH3 in 0.1 M Na2SO4, achieving a faradaic efficiency of 1.84% with an NH3 yield of 16.22 μg h−1 mgcat.−1 at a potential of −0.7 V vs RHE.

scholarly journals Communication—Partial Oxidation of MnS for Synergistic Electrocatalysis of N2-to-NH3 Fixation at Ambient Conditions

2021 ◽  
Author(s):  
Peiei Li ◽  
Dan Cheng ◽  
Xiaohua Zhu ◽  
Meiling Liu ◽  
Youyu Zhang
Keyword(s):  
Partial Oxidation ◽  
Reduction Reaction ◽  
Ambient Conditions ◽  
Faradaic Efficiency ◽  
Bosch Process ◽  
Ambient Nh3 ◽  
Reaction Performance ◽  
Excellent Selectivity

Abstract Compared with the traditional Haber-Bosch process, electrochemical N2-to-NH3 reduction affords an eco-friendly and sustainable alternative to ambient NH3 synthesis with the aid of efficient electrocatalysts. In this work, partial oxidation of MnS to obtain the MnS-Mn3O4 is proved as a promising noble-free electrocatalysts of N2to NH3 fixation at ambient conditions. When tested in 0.1 M Na2SO4, the electrochemical N2 reduction reaction performance of MnS-Mn3O4 is improved comparing with the MnS, which achieves large NH3 yield of 16.74 μg h–1 mgcat.–1 and a high Faradaic efficiency of 5.72%. It also exhibits excellent selectivity of N2-to-NH3 and strong long-term electrochemical stabil

scholarly journals CuZnAl-Oxide Nanopyramidal Mesoporous Materials for the Electrocatalytic CO2 Reduction to Syngas: Tuning of H2/CO Ratio

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3052
Author(s):  
Hilmar Guzmán ◽  
Daniela Roldán ◽  
Adriano Sacco ◽  
Micaela Castellino ◽  
Marco Fontana ◽  
...  
Keyword(s):  
Noble Metals ◽  
Co2 Reduction ◽  
Reduction Process ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
H2 Production ◽  
Ambient Conditions ◽  
Transfer Resistance ◽  
Faradaic Efficiency ◽  
Co2 Electroreduction

Inspired by the knowledge of the thermocatalytic CO2 reduction process, novel nanocrystalline CuZnAl-oxide based catalysts with pyramidal mesoporous structures are here proposed for the CO2 electrochemical reduction under ambient conditions. The XPS analyses revealed that the co-presence of ZnO and Al2O3 into the Cu-based catalyst stabilize the CuO crystalline structure and introduce basic sites on the ternary as-synthesized catalyst. In contrast, the as-prepared CuZn- and Cu-based materials contain a higher amount of superficial Cu0 and Cu1+ species. The CuZnAl-catalyst exhibited enhanced catalytic performance for the CO and H2 production, reaching a Faradaic efficiency (FE) towards syngas of almost 95% at −0.89 V vs. RHE and a remarkable current density of up to 90 mA cm−2 for the CO2 reduction at −2.4 V vs. RHE. The physico-chemical characterizations confirmed that the pyramidal mesoporous structure of this material, which is constituted by a high pore volume and small CuO crystals, plays a fundamental role in its low diffusional mass-transfer resistance. The CO-productivity on the CuZnAl-catalyst increased at more negative applied potentials, leading to the production of syngas with a tunable H2/CO ratio (from 2 to 7), depending on the applied potential. These results pave the way to substitute state-of-the-art noble metals (e.g., Ag, Au) with this abundant and cost-effective catalyst to produce syngas. Moreover, the post-reaction analyses demonstrated the stabilization of Cu2O species, avoiding its complete reduction to Cu0 under the CO2 electroreduction conditions.

Production and Study of Ca/Sn(II) Metastable Fluoride Ion Conductors

1997 ◽  
Vol 481 ◽  
Author(s):  
Michael F. Bell ◽  
Georges Dénès ◽  
Zhimeng Zhu
Keyword(s):  
Solid Solution ◽  
Electrical Conductivity ◽  
High Temperature ◽  
Calcium Nitrate ◽  
Fluoride Ion ◽  
Conductivity Measurements ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Density Measurements ◽  
Ion Conductors

ABSTRACTPrecipitation reactions from aqueous solutions of calcium nitrate and tin(II) fluoride result in the formation of two metastable phases, depending on the reaction conditions. Crystalline CaSn2F6 and the microcrystalline Ca1-xSnxF2 solid solution are obtained, the latter crystallizing in the cubic fluorite (CaF2) type with total Ca/Sn disorder. Both phases are fluoride ion conductors. Electrical conductivity measurements versus temperature and bulk density measurements show that both phases are far from thermodynamic equilibrium at ambient conditions, and thus are metastable. Both decompose to a mixture of SnF2 and CaF2 at high temperature. In addition, CaSn2F6 is chemically unstable in an aqueous medium, in which it looses SnF2 to give the microcrystalline Ca1-xSnxF2 solid solution.

Defect-rich fluorographene nanosheets for artificial N2 fixation under ambient conditions

2019 ◽  
Vol 55 (29) ◽  
pp. 4266-4269 ◽  
Author(s):  
Jinxiu Zhao ◽  
Jiajia Yang ◽  
Lei Ji ◽  
Huanbo Wang ◽  
Hongyu Chen ◽  
...  
Keyword(s):  
N2 Fixation ◽  
Formation Rate ◽  
Ambient Conditions ◽  
Faradaic Efficiency ◽  
Metal Free

Defect-rich fluorographene behaves as a metal-free catalyst for the artificial conversion of N2 to NH3 at ambient conditions. In 0.1 M Na2SO4, it achieves a faradaic efficiency (FE) of 4.2% with an NH3 formation rate (RNH3) of 9.3 μg h−1 mgcat.−1 at −0.7 V vs. RHE, with strong long-term electrochemical durability.

scholarly journals Oxygen vacancy engineering in spinel-structured nanosheet wrapped hollow polyhedra for electrochemical nitrogen fixation under ambient conditions

2020 ◽  
Vol 8 (4) ◽  
pp. 1652-1659 ◽  
Author(s):  
Feili Lai ◽  
Jianrui Feng ◽  
Xiaobin Ye ◽  
Wei Zong ◽  
Guanjie He ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Vacancy ◽  
Ambient Conditions ◽  
Faradaic Efficiency ◽  
Structured Materials ◽  
Ammonia Conversion

Electrochemical nitrogen-to-ammonia conversion under ambient conditions is realized by an oxygen vacancy-rich spinel structured materials, showing relatively high faradaic efficiency and yields.

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