scholarly journals Nanomaterials for Nitrogen Electrochemical Reduction Reactions under Ambient Conditions

2021 ◽  
Author(s):  
Juan Wen ◽  
Linqing Zuo ◽  
Haodong Sun ◽  
Xiongwei Wu ◽  
Ting Huang ◽  
...  
Keyword(s):  
Free Energy ◽  
Electrochemical Reduction ◽  
Synthesis Method ◽  
Energy Carrier ◽  
Ambient Conditions ◽  
Chemical Product ◽  
Reduction Reactions ◽  
Industrial Synthesis ◽  
Wide Range ◽  
Daily Application

As an important chemical product and carbon-free energy carrier, ammonia has a wide range of daily application in several related fields. Although the industrial synthesis method using the Haber-Bosch process...

scholarly journals Identification and elimination of false positives in electrochemical nitrogen reduction studies

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jaecheol Choi ◽  
Bryan H. R. Suryanto ◽  
Dabin Wang ◽  
Hoang-Long Du ◽  
Rebecca Y. Hodgetts ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Production Process ◽  
Electrochemical Reduction ◽  
Case Studies ◽  
False Positives ◽  
Energy Carrier ◽  
Experimental Protocol ◽  
Wide Range ◽  
The Future ◽  
Emerging Issues

Abstract Ammonia is of emerging interest as a liquefied, renewable-energy-sourced energy carrier for global use in the future. Electrochemical reduction of N2 (NRR) is widely recognised as an alternative to the traditional Haber–Bosch production process for ammonia. However, though the challenges of NRR experiments have become better understood, the reported rates are often too low to be convincing that reduction of the highly unreactive N2 molecule has actually been achieved. This perspective critically reassesses a wide range of the NRR reports, describes experimental case studies of potential origins of false-positives, and presents an updated, simplified experimental protocol dealing with the recently emerging issues.

Highly Stable Mo-Doped Fe2P and Fe3P Monolayers as Low-Onset-Potential Electrocatalysts for Nitrogen Fixation

2021 ◽  
Author(s):  
Jie Wu ◽  
Jia-hui Li ◽  
Yang-Xin Yu
Keyword(s):  
Free Energy ◽  
Nitrogen Fixation ◽  
High Selectivity ◽  
Energy Carrier ◽  
Engineering Applications ◽  
Essential Ingredient ◽  
Onset Potential ◽  
Fertilizer Production ◽  
Excellent Stability

Ammonia (NH3) is an essential ingredient for fertilizer production and a carbon-free energy carrier for engineering applications. Searching for novel electrocatalysts with low onset potential, high selectivity and excellent stability...

scholarly journals Recent Advances in Fabrication of Non-Isocyanate Polyurethane-Based Composite Materials

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3497
Author(s):  
Piotr Stachak ◽  
Izabela Łukaszewska ◽  
Edyta Hebda ◽  
Krzysztof Pielichowski
Keyword(s):  
Raw Materials ◽  
Synthesis Method ◽  
Polymeric Materials ◽  
Original Research ◽  
Significant Group ◽  
Oh Groups ◽  
New Class ◽  
Hazardous Chemical ◽  
Wide Range

Polyurethanes (PUs) are a significant group of polymeric materials that, due to their outstanding mechanical, chemical, and physical properties, are used in a wide range of applications. Conventionally, PUs are obtained in polyaddition reactions between diisocyanates and polyols. Due to the toxicity of isocyanate raw materials and their synthesis method utilizing phosgene, new cleaner synthetic routes for polyurethanes without using isocyanates have attracted increasing attention in recent years. Among different attempts to replace the conventional process, polyaddition of cyclic carbonates (CCs) and polyfunctional amines seems to be the most promising way to obtain non-isocyanate polyurethanes (NIPUs) or, more precisely, polyhydroxyurethanes (PHUs), while primary and secondary –OH groups are being formed alongside urethane linkages. Such an approach eliminates hazardous chemical compounds from the synthesis and leads to the fabrication of polymeric materials with unique and tunable properties. The main advantages include better chemical, mechanical, and thermal resistance, and the process itself is invulnerable to moisture, which is an essential technological feature. NIPUs can be modified via copolymerization or used as matrices to fabricate polymer composites with different additives, similar to their conventional counterparts. Hence, non-isocyanate polyurethanes are a new class of environmentally friendly polymeric materials. Many papers on the matter above have been published, including both original research and extensive reviews. However, they do not provide collected information on NIPU composites fabrication and processing. Hence, this review describes the latest progress in non-isocyanate polyurethane synthesis, modification, and finally processing. While focusing primarily on the carbonate/amine route, methods of obtaining NIPU are described, and their properties are presented. Ways of incorporating various compounds into NIPU matrices are characterized by the role of PHU materials in copolymeric materials or as an additive. Finally, diverse processing methods of non-isocyanate polyurethanes are presented, including electrospinning or 3D printing.

scholarly journals Formation of Carbon Quantum Dots via Hydrothermal Carbonization: Investigate the Effect of Precursors

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 986
Author(s):  
Md Rifat Hasan ◽  
Nepu Saha ◽  
Thomas Quaid ◽  
M. Toufiq Reza
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Microcrystalline Cellulose ◽  
Uv Light ◽  
Synthesis Method ◽  
Hydrothermal Carbonization ◽  
Carbon Quantum Dots ◽  
Medical Diagnostics ◽  
Particle Size Range ◽  
Wide Range

Carbon quantum dots (CQDs) are nanomaterials with a particle size range of 2 to 10 nm. CQDs have a wide range of applications such as medical diagnostics, bio-imaging, biosensors, coatings, solar cells, and photocatalysis. Although the effect of various experimental parameters, such as the synthesis method, reaction time, etc., have been investigated, the effect of different feedstocks on CQDs has not been studied yet. In this study, CQDs were synthesized from hydroxymethylfurfural, furfural, and microcrystalline cellulose via hydrothermal carbonization at 220 °C for 30 min of residence time. The produced CQDs showed green luminescence behavior under the short-wavelength UV light. Furthermore, the optical properties of CQDs were investigated using ultraviolet-visible spectroscopy and emission spectrophotometer, while the morphology and chemical bonds of CQDs were investigated using transmission electron microscopy and Fourier-transform infrared spectroscopy, respectively. Results showed that all CQDs produced from various precursors have absorption and emission properties but these optical properties are highly dependent on the type of precursor. For instance, the mean particle sizes were 6.36 ± 0.54, 5.35 ± 0.56, and 3.94 ± 0.60 nm for the synthesized CQDs from microcrystalline cellulose, hydroxymethylfurfural, and furfural, respectively, which appeared to have similar trends in emission intensities. In addition, the synthesized CQDs experienced different functionality (e.g., C=O, O-H, C-O) resulting in different absorption behavior.

PIECEWISE AFFINE SYSTEM MODELING AND CONTROL OF PWM CONVERTERS

2007 ◽  
Vol 16 (01) ◽  
pp. 113-128 ◽  
Author(s):  
FARZAD TAHAMI ◽  
BEHROOZ MOLAEI
Keyword(s):  
High Performance ◽  
Piecewise Linear ◽  
System Modeling ◽  
Synthesis Method ◽  
Operating Point ◽  
Approximation Technique ◽  
Piecewise Affine ◽  
Pwm Converters ◽  
Linear Controller ◽  
Wide Range

The averaged switch modeling approach is a powerful method for representing the behavior of a wide variety of converters through equivalent circuits. The model is not linear and it is common to perform a small signal linearization about an operating point and design a linear controller. Models obtained with such method involve considerable approximation and produce results that are limited for high performance controller designs. In this paper a piecewise affine approximation technique is introduced for modeling PWM converters. This model is much more precise in predicting the dynamic response of averaged nonlinear model comparing the linear model. This paper also presents a piecewise linear controller synthesis method for PWM converters described by the proposed PWA model. The proposed controller is very efficient and effective. The design method is well suited for converters having a wide range of variation about their operating point. A simulation example on buck-boost converter is presented to demonstrate the performance of the proposed method for modeling the dynamics of the converter and designing the appropriate controller.

The Effects of Ambient Conditions on Gas Turbine Emissions—Generalized Correction Factors

1978 ◽  
Vol 100 (4) ◽  
pp. 640-646 ◽  
Author(s):  
P. Donovan ◽  
T. Cackette
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Gas Turbine Engines ◽  
Correction Factors ◽  
Oxides Of Nitrogen ◽  
Ambient Conditions ◽  
Nitrogen Emission ◽  
Wide Range

A set of factors which reduces the variability due to ambient conditions of the hydrocarbon, carbon monoxide, and oxides of nitrogen emission indices has been developed. These factors can be used to correct an emission index to reference day ambient conditions. The correction factors, which vary with engine rated pressure ratio for NOx and idle pressure ratio for HC and CO, can be applied to a wide range of current technology gas turbine engines. The factors are a function of only the combustor inlet temperature and ambient humidity.

scholarly journals A Comprehensive Review on the Recent Development of Ammonia as a Renewable Energy Carrier

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3732
Author(s):  
Muhammad Heikal Hasan ◽  
Teuku Meurah Indra Mahlia ◽  
M. Mofijur ◽  
I.M. Rizwanul Fattah ◽  
Fitri Handayani ◽  
...  
Keyword(s):  
Free Energy ◽  
Renewable Energy ◽  
Energy Density ◽  
Co2 Emissions ◽  
Ammonia Synthesis ◽  
Ghg Emissions ◽  
Energy Carrier ◽  
Energy Sources ◽  
Comprehensive Review ◽  
Technical Advances

Global energy sources are being transformed from hydrocarbon-based energy sources to renewable and carbon-free energy sources such as wind, solar and hydrogen. The biggest challenge with hydrogen as a renewable energy carrier is the storage and delivery system’s complexity. Therefore, other media such as ammonia for indirect storage are now being considered. Research has shown that at reasonable pressures, ammonia is easily contained as a liquid. In this form, energy density is approximately half of that of gasoline and ten times more than batteries. Ammonia can provide effective storage of renewable energy through its existing storage and distribution network. In this article, we aimed to analyse the previous studies and the current research on the preparation of ammonia as a next-generation renewable energy carrier. The study focuses on technical advances emerging in ammonia synthesis technologies, such as photocatalysis, electrocatalysis and plasmacatalysis. Ammonia is now also strongly regarded as fuel in the transport, industrial and power sectors and is relatively more versatile in reducing CO2 emissions. Therefore, the utilisation of ammonia as a renewable energy carrier plays a significant role in reducing GHG emissions. Finally, the simplicity of ammonia processing, transport and use makes it an appealing choice for the link between the development of renewable energy and demand.

Electrodeposited Thin Conformal TiO2 Coating Enabling Stable Operation of BiVO4 Photoanodes in Basic Media

2018 ◽  
Vol MA2018-01 (31) ◽  
pp. 1917-1917
Author(s):  
Dongho Lee ◽  
Kyoung-Shin Choi
Keyword(s):  
Oxygen Evolution ◽  
Water Oxidation ◽  
Synthesis Method ◽  
Protective Layer ◽  
Photoelectrochemical Cell ◽  
Semiconductor Surface ◽  
Stable Operation ◽  
Solar Water Splitting ◽  
Wide Range ◽  
Basic Solutions

Producing hydrogen via solar water splitting using a photoelectrochemical cell (PEC) persists as one of the most exciting research topics in the field of solar fuels. The construction of efficient PECs requires the integration of multiple components including a photoanode, a photocathode, an oxygen evolution catalyst, and a hydrogen evolution catalyst. Therefore, the compatibility and stability of all of these elements in a given operating condition are crucial. When the stability of a semiconductor electrode used as the photoanode or photocathode is limited in an acidic or basic condition which is optimum for the operation of the other components, a thin protective layer has been deposited on the semiconductor surface to prevent its chemical dissolution. Surface coating of a thin and conformal TiO2 layer has been proven to be successful for protecting photoelectrodes since TiO2 is chemically and electrochemically stable in a wide range of pH conditions under both anodic and cathodic conditions. In order to prevent the semiconductor surface from coming into direct contact with the corrosive electrolyte, complete coverage of the photoelectrode with TiO2 is required. At the same time, the TiO2 layer should be thin enough not to interfere with the charge transport properties of the photoelectrode. As a result, atomic layer deposition (ALD) has been the only successful tool used to date to produce an effective protective layer. However, the slow processing time and economic viability of ALD methods motivated us to develop an inexpensive and facile solution-based synthesis method for the deposition of high quality TiO2 coating layers. In this presentation, we report a new electrochemical method to deposit a thin and conformal TiO2 layer on nanoporous BiVO4 that has an intricate, high surface area morphology. BiVO4 is a promising n-type photoanode material with a relatively low bandgap (2.4~2.5 eV). However, its usage has been limited to neutral and mildly basic conditions (pH 5~9) because it is chemically unstable in strongly acidic and basic conditions. Our method allows for the deposition of a 5~6 nm thick TiO2 layer on BiVO4 within 1 min and the resulting BiVO4/TiO2 electrodes exhibit chemical stability in basic solutions (pH 12~13). Sulfite oxidation measurements of BiVO4 and BiVO4/TiO2 electrodes show that the thin TiO2 protective layer does not significantly reduce the hole transfer to the electrolyte. Finally, we demonstrate the photoelectrochemical stability of the BiVO4/TiO2 electrode for photoelectrochemical water oxidation in basic solutions by coupling the BiVO4/TiO2 electrode with appropriate oxygen evolution catalysts.

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