Applications of Nanomaterials in Energy Systems

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Topic Information

Dear Colleagues,

Greetings from the Topic Editors.

We are inviting submissions to a Topic on the subject area of “Applications of Nanomaterials in Energy Systems”. This Topic is a multidisciplinary peer reviewed editorial with respect to the state of the art topics on nanomaterials while addressing cutting edge research results on exponential nanotechnology.

Publications related with original experimental work, theoretical research studies, analytical or empirical models that investigate the nanomaterials performance in energy systems, review articles updating the nanomaterials scientific community with state of the art and advances are within the scope of this Topic.

Topics of interest for publication include, but are not limited to:

• Nanocomposite dielectric materials
• Nanotechnology applications in electric components
• Nanomaterials for electrical energy storage devices
• Nanotechnology on energy transmission
• Nanotechnology applications for electrical transformers
• Nanomaterials for energy conversion
• Nanotechnology in electronics
• Super capacitors based on nanomaterials
• Photovoltaics with nanomaterials aspects
• Nanomaterials based batteries
• Nanomaterials for energy storage
• Nanomaterials for heat transfer
• Synthesis and characterization of novel nanomaterials with respect to power/energy systems
• Nanomaterials for optoelectronic/photochemical devices.

Prof. Dr. Eleftheria C. Pyrgioti
Dr. Ioannis F. Gonos
Prof. Dr. Diaa-Eldin A. Mansour
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	16.8 Days	CHF 2600
Materials materials	3.1	5.8	2008	13.9 Days	CHF 2600
Applied Sciences applsci	2.5	5.3	2011	18.4 Days	CHF 2400
Batteries batteries	4.6	4.0	2015	19.7 Days	CHF 2700
Nanoenergy Advances nanoenergyadv	-	-	2021	33.8 Days	CHF 1000

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Published Papers (15 papers)

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23 pages, 2100 KiB  

Open AccessArticle

Thermal Radiation Energy Performance on Stagnation-Point Flow in the Presence of Base Fluids Ethylene Glycol and Water over Stretching Sheet with Slip Boundary Condition

by Imran Abbas, Shahid Hasnain, Nawal A. Alatawi, Muhammad Saqib and Daoud S. Mashat

Energies 2022, 15(21), 7965; https://doi.org/10.3390/en15217965 - 27 Oct 2022

Cited by 2 | Viewed by 1623

Abstract

Nanoparticles are useful in improving the efficiency of convective heat transfer. The current study addresses this gap by making use of an analogy between Al${}_2$O${}_3$ and $\gamma$-Al${}_2$O${}_3$ nanoparticles in various base fluids across a stretched sheet [...] Read more.

Nanoparticles are useful in improving the efficiency of convective heat transfer. The current study addresses this gap by making use of an analogy between Al${}_2$O${}_3$ and $\gamma$-Al${}_2$O${}_3$ nanoparticles in various base fluids across a stretched sheet conjunction with f. Base fluids include ethylene glycol and water. We address, for the first time, the stagnation-point flow of a boundary layer of $\gamma$-Al${}_2$O${}_3$ nanofluid over a stretched sheet with slip boundary condition. Al${}_2$O${}_3$ nanofluids employ Brinkman viscosity and Maxwell’s thermal conductivity models with thermal radiations, whereas $\gamma$-Al${}_2$O${}_3$ nanofluids use viscosity and thermal conductivity models generated from experimental data. For the boundary layer, the motion equation was solved numerically using the fourth-order Runge–Kutta method and the shooting approach. Plots of the velocity profile, temperature profile, skin friction coefficient and reduced Nusselt number are shown. Simultaneous exposure of the identical nanoparticles to water and ethylene glycol, it is projected, would result in markedly different behaviors with respect to the temperature profile. Therefore, this kind of research instills confidence in us to conduct an analysis of the various nanoparticle decompositions and profile structures with regard to various base fluids. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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11 pages, 2818 KiB  

Open AccessArticle

Constructing High-Performance Carbon Nanofiber Anodes by the Hierarchical Porous Structure Regulation and Silicon/Nitrogen Co-Doping

by Yujia Chen, Jiaqi Wang, Xiaohu Wang, Xuelei Li, Jun Liu, Jingshun Liu, Ding Nan and Junhui Dong

Energies 2022, 15(13), 4839; https://doi.org/10.3390/en15134839 - 1 Jul 2022

Cited by 2 | Viewed by 2402 | Correction

Abstract

Due to the rapid development of bendable electronic products, it is urgent to prepare flexible anode materials with excellent properties, which play a key role in flexible lithium-ion batteries. Although carbon fibers are excellent candidates for preparing flexible anode materials, the low discharge [...] Read more.

Due to the rapid development of bendable electronic products, it is urgent to prepare flexible anode materials with excellent properties, which play a key role in flexible lithium-ion batteries. Although carbon fibers are excellent candidates for preparing flexible anode materials, the low discharge specific capacity prevents their further application. In this paper, a hierarchical porous and silicon (Si)/nitrogen (N) co-doped carbon nanofiber anode was successfully prepared, in which Si doping can improve specific capacity, N doping can improve conductivity, and a fabricated hierarchical porous structure can increase the reactive sites, improve the ion transport rate, and enable the electrolyte to penetrate the inner part of carbon nanofibers to improve the electrolyte/electrode contacting area during the charging–discharging processes. The hierarchical porous and Si/N co-doped carbon nanofiber anode does not require a binder, and is flexible and foldable. Moreover, it exhibits an ultrahigh initial reversible capacity of 1737.2 mAh g⁻¹, stable cycle ability and excellent rate of performance. This work provides a new avenue to develop flexible carbon nanofiber anode materials for lithium-ion batteries with high performance. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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12 pages, 3887 KiB  

Open AccessEssay

Molecular Dynamics Simulation of the Oil–Water Interface Behavior of Modified Graphene Oxide and Its Effect on Interfacial Phenomena

by Jianzhong Wang, Suo Tian, Xiaoze Liu, Xiangtao Wang, Yue Huang, Yingchao Fu and Qingfa Xu

Energies 2022, 15(12), 4443; https://doi.org/10.3390/en15124443 - 18 Jun 2022

Cited by 6 | Viewed by 2642

Abstract

Graphene oxide, as a new two-dimensional material, has a large specific surface area, high thermal stability, excellent mechanical stability and exhibits hydrophilic properties. By combining the carboxyl groups on the surface of graphene oxide with hydrophilic groups, surfactant-like polymers can be obtained. In [...] Read more.

Graphene oxide, as a new two-dimensional material, has a large specific surface area, high thermal stability, excellent mechanical stability and exhibits hydrophilic properties. By combining the carboxyl groups on the surface of graphene oxide with hydrophilic groups, surfactant-like polymers can be obtained. In this paper, based on the molecular dynamics method combined with the first nature principle, we first determine the magnitude of the binding energy of three different coupling agents—alkylamines, silane coupling agents, and haloalkanes—and analytically obtain the characteristics of the soft reaction. The high stability of alkylamines and graphene oxide modified by cetylamine, oil, and water models was also established. Then, three different chain lengths of simulated oil, modified graphene oxide–water solution, and oil-modified graphene oxide–water systems were established, and finally, the self-aggregation phenomenon and molecular morphology changes in modified graphene oxide at the oil–water interface were observed by an all-atom molecular dynamics model. The density profile, interfacial formation energy, diffusion coefficient and oil–water interfacial tension of modified graphene oxide molecules (NGOs) at three different temperatures of 300 K, 330 K, and 360 K were analyzed, as well as the relationship between the reduced interfacial tension and enhanced oil recovery (EOR). Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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15 pages, 2446 KiB  

Open AccessArticle

A Comparison of Electrical Breakdown Models for Polyethylene Nanocomposites

by Zhaoliang Xing, Chong Zhang, Mengyao Han, Ziwei Gao, Qingzhou Wu and Daomin Min

Appl. Sci. 2022, 12(12), 6157; https://doi.org/10.3390/app12126157 - 17 Jun 2022

Cited by 2 | Viewed by 2058

Abstract

The development of direct current high-voltage power cables requires insulating materials having excellent electrically insulation properties. Experiments show that appropriate nanodoping can improve the breakdown strength of polyethylene (PE) nanocomposites. Research indicates that traps, free volumes, and molecular displacement are key factors affecting [...] Read more.

The development of direct current high-voltage power cables requires insulating materials having excellent electrically insulation properties. Experiments show that appropriate nanodoping can improve the breakdown strength of polyethylene (PE) nanocomposites. Research indicates that traps, free volumes, and molecular displacement are key factors affecting the breakdown strength. This study comprehensively considered the space charge transport, electron energy gain, and molecular chain long-distance movement during the electrical breakdown process. In addition, we established three simulation models focusing on the electric field distortion due to space charges captured by traps, the energy gain of mobile electrons in free volumes, the free volume expansion caused by long-distance movement of molecular chains under the Coulomb force, and the energy gained by the electrons moving in the enlarged free volumes. The three simulation models considered the electrical breakdown modulated by space charges, with a maximum electric field criterion and a maximum electron energy criterion, and the electrical breakdown modulated by the molecular displacement (EBMD), with a maximum electron energy criterion. These three models were utilized to simulate the breakdown strength dependent on the nanofiller content of PE nanocomposites. The simulation results of the EBMD model coincided best with the experimental results. It was revealed that the breakdown electric field of PE nanodielectrics is improved synergistically by both the strong trapping effect of traps and the strong binding effect of molecular chains in the interfacial regions. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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10 pages, 410 KiB  

Open AccessArticle

Theory of Electrical Breakdown in a Nanocomposite Capacitor

by Vladimir Bordo and Thomas Ebel

Appl. Sci. 2022, 12(11), 5669; https://doi.org/10.3390/app12115669 - 2 Jun 2022

Cited by 4 | Viewed by 2085

Abstract

The electrostatic field in a nanocomposite represented by spherical nanoparticles (NPs) embedded into a dielectric between two parallel metallic electrodes is derived from first principles. The NPs are modeled by point dipoles which possess the polarizability of a sphere, and their image potential [...] Read more.

The electrostatic field in a nanocomposite represented by spherical nanoparticles (NPs) embedded into a dielectric between two parallel metallic electrodes is derived from first principles. The NPs are modeled by point dipoles which possess the polarizability of a sphere, and their image potential in the electrodes is found using a dyadic Green’s function. The derived field is used to obtain the parameters which characterize the electrical breakdown in a nanocomposite capacitor. It is found, in particular, that for relatively low volume fractions of NPs, the breakdown voltage linearly decreases with the volume fraction, and the slope of this dependence is explicitly found in terms of the dielectric permittivities of the NPs and the dielectric host. The corresponding decrease in the maximum energy density accumulated in the capacitor is also determined. A comparison with the experimental data on the breakdown strength in polymer films doped with BaTiO${}_3$ NPs available in the literature reveals a dominant role of the interface polarization at the NP-polymer interface and an existence of a nonferroelectric surface layer in NPs. This research provides a rigorous approach to the electrical breakdown phenomenon and can be used for a proper design of nanocomposite capacitors. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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10 pages, 2753 KiB  

Open AccessArticle

Flexible Porous Silicon/Carbon Fiber Anode for High−Performance Lithium−Ion Batteries

by Gang Liu, Xiaoyi Zhu, Xiaohua Li, Dongchen Jia, Dong Li, Zhaoli Ma and Jianjiang Li

Materials 2022, 15(9), 3190; https://doi.org/10.3390/ma15093190 - 28 Apr 2022

Cited by 7 | Viewed by 2876

Abstract

We demonstrate a cross−linked, 3D conductive network structure, porous silicon@carbon nanofiber (P−Si@CNF) anode by magnesium thermal reduction (MR) and the electrospinning methods. The P−Si thermally reduced from silica (SiO₂) preserved the monodisperse spheric morphology which can effectively achieve good dispersion in [...] Read more.

We demonstrate a cross−linked, 3D conductive network structure, porous silicon@carbon nanofiber (P−Si@CNF) anode by magnesium thermal reduction (MR) and the electrospinning methods. The P−Si thermally reduced from silica (SiO₂) preserved the monodisperse spheric morphology which can effectively achieve good dispersion in the carbon matrix. The mesoporous structure of P–Si and internal nanopores can effectively relieve the volume expansion to ensure the structure integrity, and its high specific surface area enhances the multi−position electrical contact with the carbon material to improve the conductivity. Additionally, the electrospun CNFs exhibited 3D conductive frameworks that provide pathways for rapid electron/ion diffusion. Through the structural design, key basic scientific problems such as electron/ion transport and the process of lithiation/delithiation can be solved to enhance the cyclic stability. As expected, the P−Si@CNFs showed a high capacity of 907.3 mAh g⁻¹ after 100 cycles at a current density of 100 mA g⁻¹ and excellent cycling performance, with 625.6 mAh g⁻¹ maintained even after 300 cycles. This work develops an alternative approach to solve the key problem of Si nanoparticles’ uneven dispersion in a carbon matrix. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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14 pages, 11023 KiB  

Open AccessArticle

Experimental Evaluation of a Full-Scale HVAC System Working with Nanofluid

by Marco Milanese, Francesco Micali, Gianpiero Colangelo and Arturo de Risi

Energies 2022, 15(8), 2902; https://doi.org/10.3390/en15082902 - 15 Apr 2022

Cited by 11 | Viewed by 2569

Abstract

Nowadays, energy saving is considered a key issue worldwide, as it brings a variety of benefits: reducing greenhouse gas emissions and the demand for energy imports and lowering costs on a household and economy-wide level. Researchers and building designers are looking to optimize [...] Read more.

Nowadays, energy saving is considered a key issue worldwide, as it brings a variety of benefits: reducing greenhouse gas emissions and the demand for energy imports and lowering costs on a household and economy-wide level. Researchers and building designers are looking to optimize building efficiency by means of new energy technologies. Changes can also be made in existing buildings to reduce the energy consumption of air conditioning systems, even during operational conditions without dramatically modifying the system layout and have as low an impact as possible on the cost of the modification. These may include the usage of new heat transfer fluids based on nanofluids. In this work, an extended experimental campaign (from February 2020 to March 2021) has been carried out on the HVAC system of an educational building in the Campus of University of Salento, Lecce, Italy. The scope of the investigation was comparing the COP for the two HVAC systems (one with nanofluid and the other one without) operating concurrently during winter and summer: simultaneous measurements on the two HVAC systems show that the coefficient of performance (COP) with nanofluid increased on average by 9.8% in winter and 8.9% in summer, with average daily peaks of about 15%. Furthermore, the comparison between the performance of the same HVAC system, working in different comparable periods with and without nanofluids, shows a mean increase in COP equal to about 13%. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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13 pages, 2689 KiB  

Open AccessArticle

Clean Electrochemical Synthesis of Pd–Pt Bimetallic Dendrites with High Electrocatalytic Performance for the Oxidation of Formic Acid

by Jie Liu, Fangchao Li, Cheng Zhong and Wenbin Hu

Materials 2022, 15(4), 1554; https://doi.org/10.3390/ma15041554 - 18 Feb 2022

Cited by 5 | Viewed by 2227

Abstract

Pd–Pt bimetallic catalysts with a dendritic morphology were in situ synthesized on the surface of a carbon paper via the facile and surfactant-free two step electrochemical method. The effects of the frequency and modification time of the periodic square-wave potential (PSWP) on the [...] Read more.

Pd–Pt bimetallic catalysts with a dendritic morphology were in situ synthesized on the surface of a carbon paper via the facile and surfactant-free two step electrochemical method. The effects of the frequency and modification time of the periodic square-wave potential (PSWP) on the morphology of the Pd–Pt bimetallic catalysts were investigated. The obtained Pd–Pt bimetallic catalysts with a dendritic morphology displayed an enhanced catalytic activity of 0.77 A mg⁻¹, almost 2.5 times that of the commercial Pd/C catalyst reported in the literature (0.31 A mg⁻¹) in acidic media. The enhanced catalytic activity of the Pd–Pt bimetallic catalysts with a dendritic morphology towards formic acid oxidation reaction (FAOR) was not only attributed to the large number of atomic defects at the edges of dendrites, but also ascribed to the high utilization of active sites resulting from the “clean” electrochemical preparation method. Besides, during chronoamperometric testing, the current density of the dendritic Pd–Pt bimetallic catalysts for a period of 3000 s was 0.08 A mg⁻¹, even four times that of the commercial Pd/C catalyst reported in the literature (about 0.02 A mg⁻¹). Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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15 pages, 4580 KiB  

Open AccessFeature PaperArticle

Facile Synthesis of Unsupported Pd Aerogel for High Performance Formic Acid Microfluidic Fuel Cell

by Alejandra Martínez-Lázaro, Luis A. Ramírez-Montoya, Janet Ledesma-García, Miguel A. Montes-Morán, Mayra P. Gurrola, J. Angel Menéndez, Ana Arenillas and Luis G. Arriaga

Materials 2022, 15(4), 1422; https://doi.org/10.3390/ma15041422 - 15 Feb 2022

Cited by 8 | Viewed by 2666

Abstract

In this work, unsupported Pd aerogel catalysts were synthesized for the very first time by using microwaves as a heating source followed by a lyophilization drying process and used towards formic acid electro-oxidation in a microfluidic fuel cell. Aerogels were also made by [...] Read more.

In this work, unsupported Pd aerogel catalysts were synthesized for the very first time by using microwaves as a heating source followed by a lyophilization drying process and used towards formic acid electro-oxidation in a microfluidic fuel cell. Aerogels were also made by heating in a conventional oven to evaluate the microwave effect during the synthesis process of the unsupported Pd aerogels. The performance of the catalysts obtained by means of microwave heating favored the formic acid electro-oxidation with H₂SO₄ as the electrolyte. The aerogels’ performance as anodic catalysts was carried out in a microfluidic fuel cell, giving power densities of up to 14 mW cm⁻² when using mass loads of only 0.1 mg on a 0.019 cm² electrode surface. The power densities of the aerogels obtained by microwave heating gave a performance superior to the resultant aerogel prepared using conventional heating and even better than a commercial Pd/C catalyst. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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17 pages, 6567 KiB  

Open AccessArticle

Design of Distributed Bragg Reflectors for Green Light-Emitting Devices Based on Quantum Dots as Emission Layer

by Iman E. Shaaban, Ahmed S. Samra, Shabbir Muhammad and Swelm Wageh

Energies 2022, 15(3), 1237; https://doi.org/10.3390/en15031237 - 8 Feb 2022

Cited by 6 | Viewed by 4630

Abstract

Light-emitting diodes based on quantum dots as an active emission can be considered as a promising next generation for application in displays and lighting. We report a theoretical investigation of green emission at 550 nm of microcavity inorganic–organic light-emitting devices based on Zn [...] Read more.

Light-emitting diodes based on quantum dots as an active emission can be considered as a promising next generation for application in displays and lighting. We report a theoretical investigation of green emission at 550 nm of microcavity inorganic–organic light-emitting devices based on Zn (Te, Se) alloy quantum dots as an active layer. Distributed Bragg Reflector (DBR) has been applied as a bottom mirror. The realization of high-quality DBR consisting of both high and low refractive index structures is investigated. The structures applied for high refractive index layers are (ZrO₂, SiN_x, ZnS), while those applied for low index layers are (Zr, SiO₂, CaF₂). DBR of ZnS/CaF₂ consisting of three pairs with a high refractive index step of ($\Delta n$ = 0.95) revealed a broad stop bandwidth (178 nm) and achieved a high reflectivity of 0.914. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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23 pages, 5669 KiB  

Open AccessReview

Applications of 2D MXenes for Electrochemical Energy Conversion and Storage

by Chenchen Ji, Haonan Cui, Hongyu Mi and Shengchun Yang

Energies 2021, 14(23), 8183; https://doi.org/10.3390/en14238183 - 6 Dec 2021

Cited by 10 | Viewed by 4313

Abstract

As newly emerged 2D layered transition metal carbides or carbonitrides, MXenes have attracted growing attention in energy conversion and storage applications due to their exceptional high electronic conductivity, ample functional groups (e.g., -OH, -F, -O), desirable hydrophilicity, and superior dispersibility in aqueous solutions. [...] Read more.

As newly emerged 2D layered transition metal carbides or carbonitrides, MXenes have attracted growing attention in energy conversion and storage applications due to their exceptional high electronic conductivity, ample functional groups (e.g., -OH, -F, -O), desirable hydrophilicity, and superior dispersibility in aqueous solutions. The significant advantages of MXenes enable them to be intriguing structural units to engineer advanced MXene-based nanocomposites for electrochemical storage devices with remarkable performances. Herein, this review summarizes the current advances of MXene-based materials for energy storage (e.g., supercapacitors, lithium ion batteries, and zinc ion storage devices), in which the fabrication routes and the special functions of MXenes for electrode materials, conductive matrix, surface modification, heteroatom doping, crumpling, and protective layer to prevent dendrite growth are highlighted. Additionally, given that MXene are versatile for self-assembling into specific configuration with geometric flexibility, great efforts about methodologies (e.g., vacuum filtration, mask-assisted filtration, screen printing, extrusion printing technique, and directly writing) of patterned MXene-based composite film or MXene-based conductive ink for fabricating more types of energy storage device were also discussed. Finally, the existing challenges and prospects of MXene-based materials and growing trend for further energy storage devices are also presented. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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10 pages, 3802 KiB  

Open AccessArticle

Co-Existence of Iron Oxide Nanoparticles and Manganese Oxide Nanorods as Decoration of Hollow Carbon Spheres for Boosting Electrochemical Performance of Li-Ion Battery

by Karolina Wenelska, Martyna Trukawka, Wojciech Kukulka, Xuecheng Chen and Ewa Mijowska

Materials 2021, 14(22), 6902; https://doi.org/10.3390/ma14226902 - 15 Nov 2021

Cited by 1 | Viewed by 2254

Abstract

Here, we report that mesoporous hollow carbon spheres (HCS) can be simultaneously functionalized: (i) endohedrally by iron oxide nanoparticle and (ii) egzohedrally by manganese oxide nanorods (Fe_xO_y/MnO₂/HCS). Detailed analysis reveals a high degree of graphitization of HCS [...] Read more.

Here, we report that mesoporous hollow carbon spheres (HCS) can be simultaneously functionalized: (i) endohedrally by iron oxide nanoparticle and (ii) egzohedrally by manganese oxide nanorods (Fe_xO_y/MnO₂/HCS). Detailed analysis reveals a high degree of graphitization of HCS structures. The mesoporous nature of carbon is further confirmed by N₂ sorption/desorption and transmission electron microscopy (TEM) studies. The fabricated molecular heterostructure was tested as the anode material of a lithium-ion battery (LIB). For both metal oxides under study, their mixture stored in HCS yielded a significant increase in electrochemical performance. Its electrochemical response was compared to the HCS decorated with a single component of the respective metal oxide applied as a LIB electrode. The discharge capacity of Fe_xO_y/MnO₂/HCS is 1091 mAhg⁻¹ at 5 Ag^–1, and the corresponding coulombic efficiency (CE) is as high as 98%. Therefore, the addition of MnO₂ in the form of nanorods allows for boosting the nanocomposite electrochemical performance with respect to the spherical nanoparticles due to better reversible capacity and cycling performance. Thus, the structure has great potential application in the LIB field. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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13 pages, 5738 KiB  

Open AccessArticle

The Effect of In Situ Synthesis of MgO Nanoparticles on the Thermal Properties of Ternary Nitrate

by Zhiyu Tong, Linfeng Li, Yuanyuan Li, Qingmeng Wang and Xiaomin Cheng

Materials 2021, 14(19), 5737; https://doi.org/10.3390/ma14195737 - 1 Oct 2021

Cited by 12 | Viewed by 2623

Abstract

The multiple eutectic nitrates with a low melting point are widely used in the field of solar thermal utilization due to their good thermophysical properties. The addition of nanoparticles can improve the heat transfer and heat storage performance of nitrate. This article explored [...] Read more.

The multiple eutectic nitrates with a low melting point are widely used in the field of solar thermal utilization due to their good thermophysical properties. The addition of nanoparticles can improve the heat transfer and heat storage performance of nitrate. This article explored the effect of MgO nanoparticles on the thermal properties of ternary eutectic nitrates. As a result of the decomposition reaction of the Mg(OH)₂ precursor at high temperature, MgO nanoparticles were synthesized in situ in the LiNO₃–NaNO₃–KNO₃ ternary eutectic nitrate system. XRD and Raman results showed that MgO nanoparticles were successfully synthesized in situ in the ternary nitrate system. SEM and EDS results showed no obvious agglomeration. The specific heat capacity of the modified salt is significantly increased. When the content of MgO nanoparticles is 2 wt %, the specific heat of the modified salt in the solid phase and the specific heat in the liquid phase increased by 51.54% and 44.50%, respectively. The heat transfer performance of the modified salt is also significantly improved. When the content of MgO nanoparticles is 5 wt %, the thermal diffusion coefficient of the modified salt is increased by 39.3%. This study also discussed the enhancement mechanism of the specific heat capacity of the molten salt by the nanoparticles mainly due to the higher specific surface energy of MgO and the semi-solid layer that formed between the MgO nanoparticles and the molten salt. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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16 pages, 2940 KiB  

Open AccessArticle

Polydopamine Coated CeO₂ as Radical Scavenger Filler for Aquivion Membranes with High Proton Conductivity

by Roberto D’Amato, Anna Donnadio, Chiara Battocchio, Paola Sassi, Monica Pica, Alessandra Carbone, Irene Gatto and Mario Casciola

Materials 2021, 14(18), 5280; https://doi.org/10.3390/ma14185280 - 14 Sep 2021

Cited by 6 | Viewed by 3235

Abstract

CeO₂ nanoparticles were coated with polydopamine (PDA) by dopamine polymerization in water dispersions of CeO₂ and characterized by Infrared and Near Edge X-ray Absorption Fine Structure spectroscopy, Transmission Electron Microscopy, Thermogravimetric analysis and X-ray diffraction. The resulting materials (PDAx@CeO₂, [...] Read more.

CeO₂ nanoparticles were coated with polydopamine (PDA) by dopamine polymerization in water dispersions of CeO₂ and characterized by Infrared and Near Edge X-ray Absorption Fine Structure spectroscopy, Transmission Electron Microscopy, Thermogravimetric analysis and X-ray diffraction. The resulting materials (PDAx@CeO₂, with x = PDA wt% = 10, 25, 50) were employed as fillers of composite proton exchange membranes with Aquivion 830 as ionomer, to reduce the ionomer chemical degradation due to hydroxyl and hydroperoxyl radicals. Membranes, loaded with 3 and 5 wt% PDAx@CeO₂, were prepared by solution casting and characterized by conductivity measurements at 80 and 110 °C, with relative humidity ranging from 50 to 90%, by accelerated ex situ degradation tests with the Fenton reagent, as well as by in situ open circuit voltage stress tests. In comparison with bare CeO₂, the PDA coated filler mitigates the conductivity drop occurring at increasing CeO₂ loading especially at 110 °C and 50% relative humidity but does not alter the radical scavenger efficiency of bare CeO₂ for loadings up to 4 wt%. Fluoride emission rate data arising from the composite membrane degradation are in agreement with the corresponding changes in membrane mass and conductivity. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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16 pages, 3068 KiB  

Open AccessArticle

The Influence of Nanoparticles’ Conductivity and Charging on Dielectric Properties of Ester Oil Based Nanofluid

by Konstantinos N. Koutras, Ioannis A. Naxakis, Eleftheria C. Pyrgioti, Vasilios P. Charalampakos, Ioannis F. Gonos, Aspasia E. Antonelou and Spyros N. Yannopoulos

Energies 2020, 13(24), 6540; https://doi.org/10.3390/en13246540 - 11 Dec 2020

Cited by 23 | Viewed by 3084

Abstract

This study addresses the effect of nanoparticles’ conductivity and surface charge on the dielectric performance of insulating nanofluids. Dispersions of alumina and silicon carbide nanoparticles of similar size (~50 nm) and concentration (0.004% w/w) were prepared in natural ester oil. [...] Read more.

This study addresses the effect of nanoparticles’ conductivity and surface charge on the dielectric performance of insulating nanofluids. Dispersions of alumina and silicon carbide nanoparticles of similar size (~50 nm) and concentration (0.004% w/w) were prepared in natural ester oil. The stability of the dispersions was explored by dynamic light scattering. AC, positive and negative lightning impulse breakdown voltage, as well as partial discharge inception voltage of the nanofluid samples were measured and compared with the respective properties of the base oil. The obtained results indicate that the addition of SiC nanoparticles can lead to an increase in AC breakdown voltage and also enhance the resistance of the liquid to the appearance of partial discharge. On the other hand, the induction of positive charge from the Al₂O₃ nanoparticles could be the main factor leading to an improved positive Lightning Impulse Breakdown Voltage and worse performance at negative polarity. Full article

(This article belongs to the Topic Applications of Nanomaterials in Energy Systems)

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