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Special Issue "New Energy Materials"

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A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 March 2014)

Special Issue Editor

Guest Editor
Prof. Dr. Duncan H. Gregory (Website)

School of Chemistry, University of Glasgow, University Avenue, Glasgow, G12 8QQ, UK
Interests: nitrides; chalcogenides; carbides; hydrides; synthesis; structure; solid state chemistry; materials chemistry

Special Issue Information

Dear Colleagues,

The environmental impact of a fossil-fuel driven economy is beginning to become a topic of major global concern. Moreover, the international energy marketplace is already changing, experiencing sometimes extreme distortions arising from the geo-political imbalances in the distribution of fossil fuel resources and infrastructure. Citizens of many nations are facing so-called “fuel poverty” for the first time in generations while others still have no means of power whatsoever.

Within the scope of finding alternative means to power the planet, the requirement to convert and store energy sustainably represents one of the biggest challenges across the boundaries of the physical sciences and engineering. Materials scientists, chemists, physicists and engineers face the demand of finding new materials (at low cost) that will provide power more efficiently or store energy (for example as heat, electricity or indirectly as a fuel) safely and at maximum density. Realising new materials design concepts will likely be essential. This special issue invites contributions in all areas of new energy materials from concepts and theoretical prediction through synthesis and characterisation to new functionalities, improved properties and enhanced performance. The scope of the issue aims to be inclusive considering among others, for example: solar materials (PV, photocatalysts etc), thermoelectrics and phase change materials, hydrogen and clean fuel storage materials, batteries (e.g. lithium ion, sodium ion, lithium-air, lithium-sulfur), fuel cell materials and supercapacitors.

Prof. Dr. Duncan Gregory
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs).

Keywords

  • synthesis
  • structure
  • properties
  • batteries
  • fuel cells
  • supercapacitors
  • photovoltaics
  • catalysts
  • thermoelectrics
  • phase change materials
  • hydrogen storage

Published Papers (8 papers)

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Research

Jump to: Review

Open AccessArticle Effect of Spark Plasma Sintering on the Structure and Properties of Ti1−xZrxNiSn Half-Heusler Alloys
Materials 2014, 7(10), 7093-7104; doi:10.3390/ma7107093
Received: 10 September 2014 / Revised: 6 October 2014 / Accepted: 9 October 2014 / Published: 20 October 2014
Cited by 6 | PDF Full-text (1156 KB) | HTML Full-text | XML Full-text
Abstract
XNiSn (X = Ti, Zr and Hf) half-Heusler alloys have promising thermoelectric properties and are attracting enormous interest for use in waste heat recovery. In particular, multiphase behaviour has been linked to reduced lattice thermal conductivities, which enables improved energy conversion efficiencies. [...] Read more.
XNiSn (X = Ti, Zr and Hf) half-Heusler alloys have promising thermoelectric properties and are attracting enormous interest for use in waste heat recovery. In particular, multiphase behaviour has been linked to reduced lattice thermal conductivities, which enables improved energy conversion efficiencies. This manuscript describes the impact of spark plasma sintering (SPS) on the phase distributions and thermoelectric properties of Ti0.5Zr0.5NiSn based half-Heuslers. Rietveld analysis reveals small changes in composition, while measurement of the Seebeck coefficient and electrical resistivities reveals that all SPS treated samples are electron doped compared to the as-prepared samples. The lattice thermal conductivities fall between 4 W·m−1·K−1 at 350 K and 3 W·m−1·K−1 at 740 K. A maximum ZT = 0.7 at 740 K is observed in a sample with nominal Ti0.5Zr0.5NiSn composition. Full article
(This article belongs to the Special Issue New Energy Materials)
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Open AccessArticle Preparation and Characterization of Li-Ion Graphite Anodes Using Synchrotron Tomography
Materials 2014, 7(6), 4455-4472; doi:10.3390/ma7064455
Received: 31 March 2014 / Revised: 26 May 2014 / Accepted: 28 May 2014 / Published: 12 June 2014
Cited by 6 | PDF Full-text (3836 KB) | HTML Full-text | XML Full-text
Abstract
We present an approach for multi-layer preparation to perform microstructure analysis of a Li-ion cell anode active material using synchrotron tomography. All necessary steps, from the disassembly of differently-housed cells (pouch and cylindrical), via selection of interesting layer regions, to the separation [...] Read more.
We present an approach for multi-layer preparation to perform microstructure analysis of a Li-ion cell anode active material using synchrotron tomography. All necessary steps, from the disassembly of differently-housed cells (pouch and cylindrical), via selection of interesting layer regions, to the separation of the graphite-compound and current collector, are described in detail. The proposed stacking method improves the efficiency of synchrotron tomography by measuring up to ten layers in parallel, without the loss of image resolution nor quality, resulting in a maximization of acquired data. Additionally, we perform an analysis of the obtained 3D volumes by calculating microstructural characteristics, like porosity, tortuosity and specific surface area. Due to a large amount of measurable layers within one stacked sample, differences between aged and pristine material (e.g., significant differences in tortuosity and specific surface area, while porosity remains constant), as well as the homogeneity of the material within one cell could be recognized. Full article
(This article belongs to the Special Issue New Energy Materials)
Open AccessArticle Characteristics of the Dye-Sensitized Solar Cells Using TiO2 Nanotubes Treated with TiCl4
Materials 2014, 7(5), 3522-3532; doi:10.3390/ma7053522
Received: 27 January 2014 / Revised: 24 April 2014 / Accepted: 29 April 2014 / Published: 5 May 2014
Cited by 11 | PDF Full-text (527 KB) | HTML Full-text | XML Full-text
Abstract
The replacement of oxide semiconducting TiO2 nano particles with one dimensional TiO2 nanotubes (TNTs) has been used for improving the electron transport in the dye-sensitized solar cells (DSSCs). Although use of one dimensional structure provides the enhanced photoelectrical performance, it [...] Read more.
The replacement of oxide semiconducting TiO2 nano particles with one dimensional TiO2 nanotubes (TNTs) has been used for improving the electron transport in the dye-sensitized solar cells (DSSCs). Although use of one dimensional structure provides the enhanced photoelectrical performance, it tends to reduce the adsorption of dye on the TiO2 surface due to decrease of surface area. To overcome this problem, we investigate the effects of TiCl4 treatment on DSSCs which were constructed with composite films made of TiO2 nanoparticles and TNTs. To find optimum condition of TNTs concentration in TiO2 composites film, series of DSSCs with different TNTs concentration were made. In this optimum condition (DSSCs with 10 wt% of TNT), the effects of post treatment are compared for different TiCl4 concentrations. The results show that the DSSCs using a TiCl4 (90 mM) post treatment shows a maximum conversion efficiency of 7.83% due to effective electron transport and enhanced adsorption of dye on TiO2 surface. Full article
(This article belongs to the Special Issue New Energy Materials)
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Open AccessArticle Structural Properties of Zinc Oxide Nanorods Grown on Al-Doped Zinc Oxide Seed Layer and Their Applications in Dye-Sensitized Solar Cells
Materials 2014, 7(4), 2522-2533; doi:10.3390/ma7042522
Received: 25 January 2014 / Revised: 20 March 2014 / Accepted: 24 March 2014 / Published: 28 March 2014
Cited by 7 | PDF Full-text (1286 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We fabricated zinc oxide (ZnO) nanorods (NRs) with Al-doped ZnO (AZO) seed layers and dye-sensitized solar cells (DSSCs) employed the ZnO NRs between a TiO2 photoelectrode and a fluorine-doped SnO2 (FTO) electrode. The growth rate of the NRs was strongly [...] Read more.
We fabricated zinc oxide (ZnO) nanorods (NRs) with Al-doped ZnO (AZO) seed layers and dye-sensitized solar cells (DSSCs) employed the ZnO NRs between a TiO2 photoelectrode and a fluorine-doped SnO2 (FTO) electrode. The growth rate of the NRs was strongly dependent on the seed layer conditions, i.e., thickness, Al dopant and annealing temperature. Attaining a large particle size with a high crystallinity of the seed layer was vital to the well-aligned growth of the NRs. However, the growth was less related to the substrate material (glass and FTO coated glass). With optimized ZnO NRs, the DSSCs exhibited remarkably enhanced photovoltaic performance, because of the increase of dye absorption and fast carrier transfer, which, in turn, led to improved efficiency. The cell with the ZnO NRs grown on an AZO seed layer annealed at 350 °C showed a short-circuit current density (JSC) of 12.56 mA/cm2, an open-circuit voltage (VOC) of 0.70 V, a fill factor (FF) of 0.59 and a power conversion efficiency (PCE, η) of 5.20% under air mass 1.5 global (AM 1.5G) illumination of 100 mW/cm2. Full article
(This article belongs to the Special Issue New Energy Materials)
Open AccessArticle Effect of the Cu Source on Optical Properties of CuZnO Films Deposited by Ultrasonic Spraying
Materials 2014, 7(2), 1261-1270; doi:10.3390/ma7021261
Received: 27 December 2013 / Revised: 17 January 2014 / Accepted: 7 February 2014 / Published: 18 February 2014
Cited by 6 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
CuZnO (CZO) films have received considerable attention, owing to their potential applications in semiconductor devices, including gas sensors or solar cells. However, exactly how these films affect the properties of CZO films by using different Cu sources has seldom been investigated. This [...] Read more.
CuZnO (CZO) films have received considerable attention, owing to their potential applications in semiconductor devices, including gas sensors or solar cells. However, exactly how these films affect the properties of CZO films by using different Cu sources has seldom been investigated. This study demonstrates the feasibility of preparing CZO films by using different Cu sources via a simple ultrasonic spray method, in which copper nitrate and copper acetate were used as copper sources. Optical properties of CZO films prepared by copper nitrate and copper acetate were also investigated, based on transmittance and photoluminescence measurements. Additionally, the composition and the morphology of the films were investigated using the X-ray diffraction analysis and field emission scanning electron microscopy. The results of this study demonstrate that the CZO films prepared by using copper acetate exhibit better optical properties. Full article
(This article belongs to the Special Issue New Energy Materials)

Review

Jump to: Research

Open AccessReview Review on Polymers for Thermoelectric Applications
Materials 2014, 7(9), 6701-6732; doi:10.3390/ma7096701
Received: 30 May 2014 / Revised: 23 August 2014 / Accepted: 5 September 2014 / Published: 18 September 2014
Cited by 26 | PDF Full-text (3268 KB) | HTML Full-text | XML Full-text
Abstract
In this review, we report the state-of-the-art of polymers in thermoelectricity. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Since the prediction of the improvement of the figure of merit by means of electronic confinement in [...] Read more.
In this review, we report the state-of-the-art of polymers in thermoelectricity. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Since the prediction of the improvement of the figure of merit by means of electronic confinement in 1993, it has been improved by a factor of 3–4. In the mean time, organic materials, in particular intrinsically conducting polymers, had been considered as competitors of classical thermoelectrics, since their figure of merit has been improved several orders of magnitude in the last few years. We review here the evolution of the figure of merit or the power factor during the last years, and the best candidates to compete with inorganic materials. We also outline the best polymers to substitute classical thermoelectric materials and the advantages they present in comparison with inorganic systems. Full article
(This article belongs to the Special Issue New Energy Materials)
Open AccessReview Donor-Acceptor Block Copolymers: Synthesis and Solar Cell Applications
Materials 2014, 7(4), 3274-3290; doi:10.3390/ma7043274
Received: 4 March 2014 / Revised: 3 April 2014 / Accepted: 15 April 2014 / Published: 22 April 2014
Cited by 8 | PDF Full-text (1020 KB) | HTML Full-text | XML Full-text
Abstract
Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs) because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with [...] Read more.
Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs) because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with donor polymeric materials and high cost for synthesis and purification. Therefore, the investigation of non-fullerene acceptor materials that can potentially replace fullerene derivatives in OPVs is increasingly necessary, which gives rise to the possibility of fabricating all-polymer (polymer/polymer) solar cells that can deliver higher performance and that are potentially cheaper than fullerene-based OPVs. Recently, considerable attention has been paid to donor-acceptor (D-A) block copolymers, because of their promising applications as fullerene alternative materials in all-polymer solar cells. However, the synthesis of D-A block copolymers is still a challenge, and therefore, the establishment of an efficient synthetic method is now essential. This review highlights the recent advances in D-A block copolymers synthesis and their applications in all-polymer solar cells. Full article
(This article belongs to the Special Issue New Energy Materials)
Open AccessReview Bismuth Telluride and Its Alloys as Materials for Thermoelectric Generation
Materials 2014, 7(4), 2577-2592; doi:10.3390/ma7042577
Received: 9 February 2014 / Revised: 21 March 2014 / Accepted: 24 March 2014 / Published: 28 March 2014
Cited by 46 | PDF Full-text (480 KB) | HTML Full-text | XML Full-text
Abstract
Bismuth telluride and its alloys are widely used as materials for thermoelectric refrigeration. They are also the best materials for use in thermoelectric generators when the temperature of the heat source is moderate. The dimensionless figure of merit, ZT, usually rises [...] Read more.
Bismuth telluride and its alloys are widely used as materials for thermoelectric refrigeration. They are also the best materials for use in thermoelectric generators when the temperature of the heat source is moderate. The dimensionless figure of merit, ZT, usually rises with temperature, as long as there is only one type of charge carrier. Eventually, though, minority carrier conduction becomes significant and ZT decreases above a certain temperature. There is also the possibility of chemical decomposition due to the vaporization of tellurium. Here we discuss the likely temperature dependence of the thermoelectric parameters and the means by which the composition may be optimized for applications above room temperature. The results of these theoretical predictions are compared with the observed properties of bismuth telluride-based thermoelements at elevated temperatures. Compositional changes are suggested for materials that are destined for generator modules. Full article
(This article belongs to the Special Issue New Energy Materials)
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