Special Issue "New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: 31 October 2020.

Special Issue Editor

Dr. Patricia Concepción
Website
Guest Editor
Instituto de Tecnología Química, CSIC-UPV, Universidad Politécnica de Valencia, Av de los Naranjos s/n, 46022 Valencia, Spain
Interests: heterogeneous catalysis; in situ spectroscopy; infrared; Raman; XPS; near ambient XPS (NAP-XPS) spectroscopy; metal nanoparticles; metal cluster

Special Issue Information

Dear Colleagues,

Metal nanoparticles have attracted great interest in the field of hetereogeneous catalysis due to their size and shape-dependent chemical and physical properties that strongly influence their catalytic activity. The main challenges in the field of nano-catalysis are the control of their synthesis, comprehensive knowledge of active sites enabling a rational design of efficient catalysts, and their characterization under reaction conditions. Despite the tremendous progress in the field, several tasks concerning the dynamic behaviour of metal nanoparticles under reaction conditions, the in situ formation of active sites, and their link with its chemical reactivity remain unresolved, limiting our capability to achieve the rational design of efficient catalysts. Therefore, new strategies aimed at the identification of active sites, reaction mechanisms, and the controlled synthesis of disruptive novel catalysts are strongly required.

This Special Issue seeks to highlight the most recent results contributing to an advanced understanding of heterogeneous catalysts providing stimulating contributions in the synthesis, characterization, and catalytic application of metal nanoparticles in heterogeneous catalysis.

We kindly invite you to submit a manuscript to this Special Issue entitled “New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis”.

Potential topics include but are not limited to the following:

  • Surface science;
  • Computational modelling;
  • Reaction engineering;
  • In situ spectroscopy;
  • Mechanistic insights;
  • Kinetics of surface reactions;
  • Transient studies.

Dr. Patricia Concepción
Guest Editor

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. Nanomaterials 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 2000 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

  • Metal nanoparticles
  • Metal clusters
  • Heterogeneous catalysis
  • In situ spectroscopy
  • Mechanistic insights
  • Theoretical modelling.

Published Papers

This special issue is now open for submission, see below for planned papers.

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: New carbon magnetic nanocomposites to accelerate the biological removal of micropollutants under anaerobic conditions
Authors: Ana R. Silva^1, O.S.G.P. Soares^2, M. Fernando R. Pereira^2, M. Madalena Alves^1, Luciana Pereira^1,*
Affiliation: 1Centre of Biological Engineering, University of Minho, Braga, Portugal 2Laboratory of Separation and Reaction Engineering − Laboratory of Catalysis and Materials (LSRE-LCM), Faculty of Engineering, University of Porto, Porto, Portugal *Email: [email protected]
Abstract: Water pollution is one of the serious problems worldwide. The industrialization growth, associated with the ineffective wastewater treatments, leads to the contamination of water resources with different pollutants, including azo dyes. Anaerobic treatments have been described for the biodegradation of micropollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Notwithstanding, the low transformation rates of many recalcitrant compounds in the anaerobic bioprocesses, mainly due to electron transfer limitations, may represent a drawback to their application (van der Zee et al., 2001). Redox mediators (RM) are organic molecules that can reversibly be oxidized and reduced, acting as an electron carrier in multiple redox reactions. RM can accelerate the global reaction rates, by lowering the corresponding activation energy (van der Zee and Cervantes, 2009). In previous studies in our group, the rates of reduction of dyes and of aromatic amines was greatly improved, in batch and in continuous bioreactors, by adding low amounts (0.1 g L-1) of different carbon materials (CM) (Pereira et al., 2010; 2014; 2016a; 2016b) and magnetic carbon nanocomposites (MNC) (Pereira et al., 2017) and, in some cases, no reduction occurred in their absence. The proved efficiency of CM and MNC as RM is mainly due to their high surface area, proper pore size and excellent catalytic properties. In addition, insoluble materials like CM can be retained in the bioreactors, avoiding the need of being continuously added during the process, and are easier to remove after the process. The magnetic properties of magnetic composites allowed their easier recover from the reactors, by using a magnetic field, and their reuse in successive cycles, maintaining the RM characteristic. In the present work, different carbon nanotubes (CNT) with modified surface chemistry, namely CNT oxidized with HNO3 (CNT_HNO3) and CNT doped with Nitrogen in a ball milling process (CNT_MB) were prepared taking a commercial CNT as template. Also, magnetic CNT were prepared by impregnation with 2% of iron and modified similarly as CNT ([email protected]%Fe; [email protected]%Fe_HNO3 and [email protected]%Fe_MB). The new CM were tested as RM (0.1 g L-1) in the biological removal of the azo dye Acid Orange 10 (AO10), with anaerobic granular sludge, over 29h of reaction. Methane production was also assessed to verify the microorganism’s activity and CM effect on the methanogenic activity. Improvement of the biological removal of AO10 was observed, in the presence of all CM (above 90%) when compared with the control without CM (only (29±3) %. The best results were obtained with the CNT_MB, leading to (98±1) % of biological AO10 removal at the rate of (2.94±0.18) d-1, a 11-fold degradation rate increase (Figure 1). The CNT_MB has high surface area, pore volume, and a pH of point of zero charge (pHpzc) higher than commercial CNT, enhancing the electrostatic interaction of the process and consequently the electrons shuttling. Any dye removal was observed in the abiotic assays, so the removal was not due to adsorption on the CM. The results obtained in the presence of [email protected]%Fe, were similar to the results obtained with the corresponding modified CNT, but their magnetic properties allow their recover and reuse. Furthermore, the microorganism’s viability was maintained during the assay and methane production was not affected by the presence of different CM. The removal of AO10 was improved by the presence of CM, which act as RM. The surface chemistry of these materials is an important factor for the catalysis, so, tailoring CM for specific micropollutants is logic. In this work, CNT_MB and [email protected]%Fe_MB were the most effective as RM. This preliminary screening using an azo dye as model pollutant, shows the possibility for the implementation in high-rate anaerobic reactors for micropollutants biological removal, in a sustainable way, by the recover and reuse of the magnetic CM.

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