Special Issue "Emerging Nanostructured Catalytic Materials for Energy and Environmental Applications"

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (30 September 2020).

Special Issue Editors

Prof. Anantha-Iyengar Gopalan
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Guest Editor
Daeyong Regional Infrastructure Technology Development Center, Kyungpook National University, Daegu, South Korea
Interests: electrochemistry, polymer science, nanostructured materials, energy devices
Dr. Saianand Gopalan
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Guest Editor
Global Center for Environmental Remediation, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan Campus NSW 2308, Australia
Interests: Electrocatalysis, Materials Science, Energy Materials, Flexible and Organic Electronics, Nanotechnology
Prof. Kwang-Pill Lee

Guest Editor
Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu 41566, South Korea
Interests: nanomaterials, sensors, environmental applications

Special Issue Information

Dear Colleagues,

 In recent years, there has been great demand for the development of catalytic materials at the nanoscale (defined in general as 1–100 nm size scale) with a view to more accurately and efficiently control the reaction pathways. The development of next-generation nanostructured catalytic materials (NCM) relies on synthesis approaches, which can be suitable to produce stable surface-active sites through controlling the size, shape, and chemical composition of nanostructured catalysts and the surface characterization techniques that can determine catalytic activities.

The advances in NCM in the last ten years support a new vision for the nanoscience-inspired design, synthesis, and formulation of new NCM with high activities for energetically challenging reactions, high selectivity to valuable products, extended life times, and recyclability leading to the production of industrially important catalytic materials. Success has been achieved to a great extent, but exploration of developing new NCM through the precise control of the composition and structure of the materials (metals, polymers, alloys, composites, hybrids, etc.) of choice is continuing. Tremendous efforts are being made to design innovative catalysts that can be utilized in a multitude of applications. The implications of further progress in the development of new NCM and applications in the areas of energy and the environment are profound. 

This Special Issue is aimed at covering the latest progress and advances on emerging NCM to overcome the current issues and challenges with regards to synthesis and properties in the fields of energy (conversion and storage) and environment-related applications. We believe that this Special Issue will provide an excellent platform for researchers to share their newest scientific advancements in the field of NCM focusing on energy and environmental applications. Authors with adequate expertise on these topics are cordially invited to submit their contributions to Catalysts.  

We invite contributions in the form of original research papers, detailed reviews, or mini-reviews in, but not limited to, the specialized fields outlined below.

Prof. Anantha-Iyengar Gopalan
Dr. Saianand Gopalan
Prof. Kwang-Pill Lee
Guest Editors

Manuscript Submission Information

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. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts 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 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanostructured catalysts for energy conversion and storage
  • Semiconductor nanostructured materials for energy and environmental applications
  • Environmental remediation
  • Supported nanocatalysts
  • Nanostructured electrocatalysts
  • Nanostructured photocatalysts
  • Nanostructured photoelectrocatalysts
  • Nanostructured bio/photobiocatalysts
  • Nanostructured catalysts for photosynthesis/artificial photosynthesis
  • Nanostructured membranes for water purifications
  • Photoelectrochemical water splitting
  • Oxygen reduction reaction
  • Oxygen/hydrogen evolution reaction
  • Bioinspired catalysts
  • Sustainable/clean energy

Published Papers (11 papers)

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Research

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Open AccessArticle
Facile Synthesis of Porous Hexapod [email protected] Dual Catalysts for In Situ SERS Monitoring of 4-Nitrothiophenol Reduction
Catalysts 2020, 10(7), 746; https://doi.org/10.3390/catal10070746 - 05 Jul 2020
Abstract
Controllable morphological metal catalytic materials have always been a focus in research. In the previous work, hexapod AgCl was successfully synthesized. In this paper, hexapod [email protected] microstructures with diverse Ag contents are prepared through NaBH4 reduction. They are characterized by scanning electron [...] Read more.
Controllable morphological metal catalytic materials have always been a focus in research. In the previous work, hexapod AgCl was successfully synthesized. In this paper, hexapod [email protected] microstructures with diverse Ag contents are prepared through NaBH4 reduction. They are characterized by scanning electron microscopy (SEM) and the element distribution is proved by an energy dispersive X-ray spectrometer (EDS). They are porous dendritic microstructures with a large specific surface area and a rough surface, which display high catalytic performance and surface-enhanced Raman spectroscopy (SERS) activity. Furthermore, the hexapod [email protected] microstructure is devoted as a dual catalyst to monitor the reduction of 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP) in situ using SERS. Ultraviolet–visible (UV–Vis) spectroscopy was employed to evaluate the catalytic performance of the hexapod [email protected] microstructures. The consequences show that the velocity of reaction became faster with a corresponding increase in silver content and the reaction mechanism was cleared. In addition to preparing a good catalyst, this work also promotes the combination of micro-nano materials and spectroscopy technology. Full article
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Open AccessArticle
Reduced Graphene Oxide/ZnIn2S4 Nanocomposite Photocatalyst with Enhanced Photocatalytic Performance for the Degradation of Naproxen under Visible Light Irradiation
Catalysts 2020, 10(6), 710; https://doi.org/10.3390/catal10060710 - 24 Jun 2020
Abstract
The development of photocatalysts with visible light response is of great significance to cope with energy crisis and environmental remediation. In this study, a visible light-driven photocatalyst reduced graphene oxide/ZnIn2S4 (rGO/ZIS) was prepared by a facile one-pot hydrothermal method. The [...] Read more.
The development of photocatalysts with visible light response is of great significance to cope with energy crisis and environmental remediation. In this study, a visible light-driven photocatalyst reduced graphene oxide/ZnIn2S4 (rGO/ZIS) was prepared by a facile one-pot hydrothermal method. The photocatalyst was used for the degradation of naproxen under visible light illumination and it exhibited remarkably degradation efficiency (nearly 99% within 60 min). The improved photocatalytic degradation performance can be attributed to the enhancement of light adsorption capacity and effective separation of photoinduced electron–hole pairs. The reactive species quenching experiments and EPR measurements demonstrated that superoxide radical (–O2) and hole (h+) play a dominant role in the photocatalytic degradation reactions. In addition, the degradation intermediates were identified and the degradation pathway was suggested. Full article
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Open AccessArticle
Pt-Amorphous Barium Aluminum Oxide/Carbon Catalysts for an Enhanced Methanol Electrooxidation Reaction
Catalysts 2020, 10(6), 708; https://doi.org/10.3390/catal10060708 - 24 Jun 2020
Abstract
A new type of amorphous barium aluminum oxide was synthesized using a polyol thermal method involving a mixture with Vulcan XC-72 carbon and supported with 20%Pt catalysts to enhance the activity of a methanol electrooxidation reaction (MOR). The maximum current density, electrochemically active [...] Read more.
A new type of amorphous barium aluminum oxide was synthesized using a polyol thermal method involving a mixture with Vulcan XC-72 carbon and supported with 20%Pt catalysts to enhance the activity of a methanol electrooxidation reaction (MOR). The maximum current density, electrochemically active surface area (ECSA), and electrochemical impedance spectra (EIS) of the obtained catalysts for MOR were determined. The MORs of barium aluminum oxide with different calcination temperatures and Ba and Al contact ratios were studied. The MOR of the uncalcined amorphous Ba0.5AlOx catalysts prepared with a mole ratio of 2/1 Ba/Al mixed with Vulcan XC-72 carbon and supported with 20%Pt catalyst (Pt-Ba0.5AlOx/C) was enhanced compared with that of 20%Pt-Al2O3/C and 20%Pt/C catalysts due to its obtained largest maximum current density of 3.89 mA/cm2 and the largest ECSA of 49.83 m2/g. Therefore, Pt-Ba0.5AlOx/C could provide a new pathway to achieve a sufficient electrical conductivity, and possible synergistic effects with other active components improved the catalytic activity and stability of the prepared catalyst in MOR. Full article
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Open AccessFeature PaperArticle
Synthesis and Evaluation of PtNi Electrocatalysts for CO and Methanol Oxidation in Low Temperature Fuel Cells
Catalysts 2020, 10(5), 563; https://doi.org/10.3390/catal10050563 - 19 May 2020
Cited by 1
Abstract
Pt(Ni)/C and PtRu(Ni)/C catalysts were synthesized by electroless deposition of Ni on a carbon dispersion followed by sequenced Pt deposition and spontaneous deposition of Ru species. The structural analyses of the catalysts with 88:12 and 98:2 Pt:Ni atomic ratios pointed out to the [...] Read more.
Pt(Ni)/C and PtRu(Ni)/C catalysts were synthesized by electroless deposition of Ni on a carbon dispersion followed by sequenced Pt deposition and spontaneous deposition of Ru species. The structural analyses of the catalysts with 88:12 and 98:2 Pt:Ni atomic ratios pointed out to the formation of small hexagonal Ni crystallites covered by thin cubic Pt surface structures with no evidence about PtNi alloy formation. The onset potentials for CO oxidation on Pt(Ni)/C and PtRu(Ni)/C were about 0.10 and 0.24 V more negative than those of Pt/C, thus indicating their better CO tolerance. The surface Ru species appeared to have the major effect by facilitating the CO removal by the bifunctional mechanism. The onset potential for the methanol oxidation reaction (MOR) of Pt(Ni)/C was about 0.15 V lower than that of Pt/C. The mass and specific activities together with the exchange current densities of the Pt(Ni)/C catalysts were also higher than those of Pt/C, making in evidence their higher activity in front of the MOR. The Tafel slopes for the MOR on Pt(Ni)/C suggested different reaction mechanism than on Pt/C. The electronic (ligand) effect of Ni on Pt was considered the main reason to explain the higher activity of Pt(Ni)/C in front of the CO oxidation and the MOR. Full article
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Open AccessArticle
Photocatalytic Activities of PET Filaments Deposited with N-Doped TiO2 Nanoparticles Sensitized with Disperse Blue Dyes
Catalysts 2020, 10(5), 531; https://doi.org/10.3390/catal10050531 - 11 May 2020
Cited by 2
Abstract
In this study, the enhanced photocatalytic activities of polyethylene terephthalate (PET) filaments deposited with N-doped Titanium dioxide (TiO2) nanoparticles sensitized with water insoluble disperse blue SE–2R dye were investigated. The PET filaments were loaded with two types of N-doped TiO2 [...] Read more.
In this study, the enhanced photocatalytic activities of polyethylene terephthalate (PET) filaments deposited with N-doped Titanium dioxide (TiO2) nanoparticles sensitized with water insoluble disperse blue SE–2R dye were investigated. The PET filaments were loaded with two types of N-doped TiO2 nanoparticles, one with and the other without being sensitized with disperse blue SE–2R dye, in one-pot hydrothermal process respectively. The differences in photocatalytic activities between the N-doped TiO2 and the dye-sensitized N-doped TiO2 nanoparticles when exposed to both UV rays and visible lights were analyzed and compared by using their photodegradations of methylene blue (MB) dye. It was demonstrated that the disperse blue dye facilitated the electron–hole separation in N-doped TiO2 nanoparticles faster under UV irradiation than that under visible light irradiation. The enhanced photocatalytic activity of the PET filaments loaded with dye-sensitized N-doped TiO2 nanoparticles exposure to UV irradiation, in comparison with that under visible light irradiation, was attributed to both improved light absorption capacity and high separation efficiency of photo-generated electron–hole pairs. Furthermore, the conduction band and band gap of the PET filaments deposited with N-doped TiO2 nanoparticles sensitized with disperse blue SE–2R dye were influenced by the wavelength of light sources, while its valence band was not affected. The PET filaments deposited with dye-sensitized N-doped TiO2 nanoparticles have a potential application to degrade organic pollutants. Full article
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Open AccessArticle
Photodegradation of Gas Phase Benzene by SnO2 Nanoparticles by Direct Hole Oxidation Mechanism
Catalysts 2020, 10(1), 117; https://doi.org/10.3390/catal10010117 - 14 Jan 2020
Cited by 2
Abstract
Photodegradation of gas phase benzene by SnO2 nanoparticles has been studied in humid air, dry air and N2 by using a tubular photoreactor. The SnO2 nanoparticles are synthesized by the oxidation of anhydrous stannic chloride (SnCl4) in a [...] Read more.
Photodegradation of gas phase benzene by SnO2 nanoparticles has been studied in humid air, dry air and N2 by using a tubular photoreactor. The SnO2 nanoparticles are synthesized by the oxidation of anhydrous stannic chloride (SnCl4) in a propane/air turbulent flame. Direct hole oxidation and the ·OH radical mechanisms have been discussed based on experimental results. The goal of this research is to explore a viable and efficient alternative photocatalyst and photocatalytic process, in particular, for humidity-tolerant photocatalyst or photocatalytic process in environmental applications. Full article
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Open AccessArticle
A Comparative Evaluation of Physicochemical Properties and Photocatalytic Efficiencies of Cerium Oxide and Copper Oxide Nanofluids
Catalysts 2020, 10(1), 34; https://doi.org/10.3390/catal10010034 - 26 Dec 2019
Cited by 2
Abstract
Copper oxide (CuO) and cerium oxide (CeO2) of various concentrations have been prepared through an ultrasonically assisted dispersion of CuO and CeO2 nanoparticles (NPs) in which water and nanofluids (NFs) were formulated. The morphological properties of the CuO and CeO [...] Read more.
Copper oxide (CuO) and cerium oxide (CeO2) of various concentrations have been prepared through an ultrasonically assisted dispersion of CuO and CeO2 nanoparticles (NPs) in which water and nanofluids (NFs) were formulated. The morphological properties of the CuO and CeO2 NPs are reported. Few of the physicochemical properties that can influence the photocatalytic activities of the NFs are evaluated, such as viscosity, activation energy, density, thermal conductivity, electrical conductivity, alternating current (AC) conductivity, pH, stability, refractive index and optical band gap of the CuO and CeO2 NFs. Viscosity studies have been made at four different temperatures (303 K, 308 K, 313 K and 318 K) and the activation energy is calculated and compared between the CuO and CeO2 NFs. The thermal conductivity of the two NFs is calculated and compared. Electrical conductivity is measured for CuO and CeO2 NFs using an impedance analyzer at different frequencies at 303 K. The dielectric constant and AC conductivity were studied. The electrical conductivity and pH of the prepared NFs are measured and the results are compared. The stability of the NFs is determined from Zeta potential values obtained from dynamic light scattering measurements. UV-Visible diffuse reflectance measurements were used to deduce the optical bandgap of the respective metal oxide NPs in the NFs. The photocatalytic efficiencies of the CuO NFs and CeO2 NFs were evaluated using methylene blue (MB) as the model dye. The rate constant for the photodegradation of MB was higher for CuO NF as compared CeO2 NF and also higher than simple NPs-based photocatalysts. A plausible explanation for the role of NFs over the simple NPs-based photocatalytic solution is presented. Full article
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Open AccessArticle
Facile Fabrication of Metal Oxide Based Catalytic Electrodes by AC Plasma Deposition and Electrochemical Detection of Hydrogen Peroxide
Catalysts 2019, 9(11), 888; https://doi.org/10.3390/catal9110888 - 25 Oct 2019
Cited by 4
Abstract
In this study, the fabrication of a metal oxide nanoparticles (NPs) dispersed catalytic electrode is described based on a new alternating current (AC) plasma deposition approach. The fabrication involves the treatment of AC plasma on a precursor solution comprised of metal salts such [...] Read more.
In this study, the fabrication of a metal oxide nanoparticles (NPs) dispersed catalytic electrode is described based on a new alternating current (AC) plasma deposition approach. The fabrication involves the treatment of AC plasma on a precursor solution comprised of metal salts such as CuCl2, FeCl2, and ZnCl2, and a monomer (acrylic acid) in the presence/absence of a cross-linker. Furthermore, the utility of such developed electrodes has been demonstrated for the electrochemical determination of hydrogen peroxide (H2O2). The electrode materials obtained through plasma treatment was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), contact angle measurements, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. Among the metal oxide modified electrodes prepared by the AC plasma deposition method, the copper oxide (CuO) NPs catalytic electrode exhibited significant oxidation and reduction peaks for H2O2 in phosphate-buffered saline solution. The catalytic electrode with CuO NPs exhibited a combination of good H2O2 sensing characteristics such as good sensitivity (63.52 mA M−1 cm−2), good selectivity, low detection limits (0.6 µM), fast sensing response (5 s), a wide linear range (0.5–8.5 mM), and good stability over 120 cycles. Based on our results, it is well demonstrated that plasma deposition could be effectively utilized for the fabrication of the catalytic electrode for detection of H2O2 concentrations. Further, the strategy of using AC plasma for fabrication of metal oxide-based modified electrodes could also be extended for the fabrication of other kinds of nanomaterials-based sensors. Full article
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Open AccessArticle
Efficient Photocatalytic Hydrogen Peroxide Production over TiO2 Passivated by SnO2
Catalysts 2019, 9(7), 623; https://doi.org/10.3390/catal9070623 - 21 Jul 2019
Cited by 6
Abstract
Photocatalysis provides an attractive strategy for synthesizing H2O2 at ambient condition. However, the photocatalytic synthesis of H2O2 is still limited due to the inefficiency of photocatalysts and decomposition of H2O2 during formation. Here, we [...] Read more.
Photocatalysis provides an attractive strategy for synthesizing H2O2 at ambient condition. However, the photocatalytic synthesis of H2O2 is still limited due to the inefficiency of photocatalysts and decomposition of H2O2 during formation. Here, we report SnO2-TiO2 heterojunction photocatalysts for synthesizing H2O2 directly in aqueous solution. The SnO2 passivation suppresses the complexation and decomposition of H2O2 on TiO2. In addition, loading of Au cocatalyst on SnO2-TiO2 heterojunction further improves the production of H2O2. The in situ electron spin resonance study revealed that the formation of H2O2 is a stepwise single electron oxygen reduction reaction (ORR) for Au and SnO2 modified TiO2 photocatalysts. We demonstrate that it is feasible to enhance H2O2 formation and suppress H2O2 decomposition by surface passivation of the H2O2-decomposition-sensitive photocatalysts. Full article
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Open AccessFeature PaperEditor’s ChoiceArticle
Preparation of Visible Light Photocatalytic Graphene Embedded Rutile Titanium(IV) Oxide Composite Nanowires and Enhanced NOx Removal
Catalysts 2019, 9(2), 170; https://doi.org/10.3390/catal9020170 - 11 Feb 2019
Cited by 16
Abstract
The quest for developing highly efficient TiO2-based photocatalysts is continuing and, in particular, evolving a new strategy is an important aspect in this regard. In general, much effort has been devoted to the anatase TiO2 modifications, despite there being only [...] Read more.
The quest for developing highly efficient TiO2-based photocatalysts is continuing and, in particular, evolving a new strategy is an important aspect in this regard. In general, much effort has been devoted to the anatase TiO2 modifications, despite there being only a few recent studies on rutile TiO2 (rTiO2). To the best of our knowledge, studies on the preparation and characterization of the photocatalysts based on the intentional inclusion of graphene (G) into rTiO2 nanostructures have not been reported yet. Herein, we develop a new type of TiO2-based photocatalyst comprising of G included pure rTiO2 nanowire (abbreviated as rTiO2(G) NW) with enhanced visible light absorption capability. To prepare rTiO2(G) NW, the G incorporated titanate electrospun fibers were obtained by electrospinning and subsequently heat treated at various temperatures (500 to 800 °C). Electrospinning conditions were optimized for producing good quality rTiO2(G) NW. The rTiO2(G) NW and their corresponding samples were characterized by appropriate techniques such as X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy and UV-vis diffuse reflectance spectroscopy to ascertain their material characteristics. XRD results show that the lattice strain occurs upon inclusion of G. We present here the first observation of an apparent bandgap lowering because of the G inclusion into TiO2 NW. While anatase TiO2 NW exhibited poor visible light photocatalysis towards NOx removal, the rTiO2(G) NW photocatalyst witnessed a significantly enhanced (~67%) photocatalytic performance as compared to anatase TiO2(G) NW. We concluded that the inclusion of G into rTiO2 nanostructures enhances the visible light photoactivity. A plausible mechanism for photocatalysis is suggested. Full article
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Review

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Open AccessReview
The Development of Catalyst Materials for the Advanced Lithium–Sulfur Battery
Catalysts 2020, 10(6), 682; https://doi.org/10.3390/catal10060682 - 17 Jun 2020
Cited by 1
Abstract
The lithium–sulfur battery is considered as one of the most promising next-generation energy storage systems owing to its high theoretical capacity and energy density. However, the shuttle effect in lithium–sulfur battery leads to the problems of low sulfur utilization, poor cyclability, and rate [...] Read more.
The lithium–sulfur battery is considered as one of the most promising next-generation energy storage systems owing to its high theoretical capacity and energy density. However, the shuttle effect in lithium–sulfur battery leads to the problems of low sulfur utilization, poor cyclability, and rate capability, which has attracted the attention of a large number of researchers in the recent years. Among them, the catalysts with efficient catalytic function for lithium polysulfides (LPSs) can effectively inhibit the shuttle effect. This review outlines the progress of catalyst materials for lithium–sulfur battery in recent years. Based on the structure and properties of the reported catalysts, the development of the reported catalyst materials for LPSs was divided into three generations. We can find that the design of highly efficient catalytic materials needs to consider not only strong chemical adsorption on polysulfides, but also good conductivity, catalysis, and mass transfer. Finally, the perspectives and outlook of reasonable design of catalyst materials for high performance lithium–sulfur battery are put forward. Catalytic materials with high conductivity and both lipophilic and thiophile sites will become the next-generation catalytic materials, such as heterosingle atom catalysis and heterometal carbide. The development of these catalytic materials will help catalyze LPSs more efficiently and improve the reaction kinetics, thus providing guarantee for lithium sulfur batteries with high load or rapid charge and discharge, which will promote the practical application of lithium–sulfur battery. Full article
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