Special Issue "Nanomaterials for Photocatalytic Degradation of Organic Pollutants and Inactivation of Microorganisms"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Photocatalysis".

Deadline for manuscript submissions: closed (31 January 2021).

Special Issue Editor

Prof. Dr. Anna Zielińska-Jurek
E-Mail Website
Guest Editor
Department of Process Engineering and Chemical Technology, Gdansk University of Technology, Gdansk, Poland
Interests: heterogeneous photocatalysis; visible-light active photocatalysts; noble metals; photocatalytic purification of water and air; functional material synthesis and characterization; environmental technology; separation of photocatalyst after purification; photoreactor design and development; nanotechnology; magnetic photocatalysts; degradation of pharmaceuticals

Special Issue Information

Dear Colleagues,

This Special Issue is dedicated to new trends and achievements in research work focused on photocatalysis and advanced photocatalytic materials for the degradation of recalcitrant compounds and xenobiotics.

Heterogeneous photocatalysis is highly appreciated for the removal of organic contaminants of emerging concern from gas and aqueous phases, since, under specific conditions, reactive oxygen species are generated in situ. The capacity of chemical treatment processes to increase the biodegradability of non-biodegradable compounds by, for instance, a strong oxidant attack provides the possibility of efficiently combining them with photocatalytic materials. Therefore, photocatalysis is an alternative or synergetic process for biological degradation. At present, the need to develop ecologically clean solar-induced chemical processes, such as photocatalysis, are limited by low quantum efficiencies. Among various efforts to extend photocatalysis, special attention is focused on the design of semiconductor materials with specific morphologies and microstructures in order to enhance their ability to photodegrade persistent organic pollutants. In this regard, it is highly required to improve the performance of semiconductors by a suitable architecture which integrates the usually incompatible features of large specific surface area, high charge-carrier mobility, low electron-hole recombination rate.

This Special Issue aims to report recent progress and developments in the design and synthesis of highly functional nanostructured photocatalysts with enhanced properties. Furthermore, research to understand the mechanisms of photocatalytic degradation of persistent organic pollutants and the processing–structure–property relationships is also of great interest to this Special Issue.

Prof. Dr. Anna Zielińska-Jurek
Guest Editor

Manuscript Submission Information

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Keywords

  • nanomaterials design and synthesis
  • advanced 2D nanomaterials
  • nanostructured photocatalysts
  • environmental remediation
  • water and air contamination
  • reaction kinetics and mechanism
  • surface and microstructural properties
  • processing–structure–property relationships
  • smart nanomaterials for recyclable-photocatalysis applications
  • degradation of pharmaceutical compounds
  • biological-photocatalytic process
  • degradation of textile dye
  • photocatalytic disinfection

Published Papers (11 papers)

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Research

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Article
Photocatalytic Degradation of Diazinon with a 2D/3D Nanocomposite of Black Phosphorus/Metal Organic Framework
Catalysts 2021, 11(6), 679; https://doi.org/10.3390/catal11060679 - 27 May 2021
Viewed by 477
Abstract
Metal–organic frameworks (MOFs) are promising materials for the removal and photodegradation of pesticides in water. Characteristics such as large surface area, crystalline structure and catalytic properties give MOFs an advantage over other traditional adsorbents. The application of MOFs in environmental remediation is hindered [...] Read more.
Metal–organic frameworks (MOFs) are promising materials for the removal and photodegradation of pesticides in water. Characteristics such as large surface area, crystalline structure and catalytic properties give MOFs an advantage over other traditional adsorbents. The application of MOFs in environmental remediation is hindered by their ability to only absorb in the UV region. Therefore, combining them with an excellent charge carrier 2D material such as black phosphorus (BP) provides an attractive composite for visible-light-driven degradation of pesticides. In the study, a nanocomposite of black phosphorus and MIL-125(Ti), defined as BpMIL, was prepared using a two-stage hydrothermal and sonication route. The as-prepared composite was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectroscopy. These techniques revealed that the circular and sheet-like morphology of the nanocomposites had minimum charge recombination, allowing them to be effective photocatalysts. Furthermore, the photocatalysts exhibited extended productive utilization of the solar spectrum with inhibited recombination rate and could be applied in visible-light-driven water treatment. The photodegradation of diazinon in water was studied using a series of BpMIL (4%, 6% and 12% by mass) nanocomposites as a photocatalyst. The optimal composite was determined to be 4%BpMIL. The degradation parameters were optimized and these included photocatalyst dosage, initial diazinon concentration and pH of the solution. The optimal conditions for the removal and degradation of diazinon were: neutral pH, [diazinon] = 20 mg/L, photocatalyst dosage = 0.5 g/L, achieving 96% removal of the pesticide after 30 min with 4%BpMIL, while MIL-125(Ti) showed 40% removal. The improved photodegradation efficiency of the 4%BpMIL composite was attributed to Ti3+-Ti4+ intervalence electron transfer and the synergistic effect between MIL-125(Ti) and BP. The photodegradation followed pseudo-first-order kinetics with a rate constant of 1.6 × 10−2 min−1. Full article
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Article
Synthesis and Characterization of Iron-Doped TiO2 Nanoparticles Using Ferrocene from Flame Spray Pyrolysis
Catalysts 2021, 11(4), 438; https://doi.org/10.3390/catal11040438 - 29 Mar 2021
Cited by 1 | Viewed by 391
Abstract
Iron-doped titanium dioxide nanoparticles, with Fe/Ti atomic ratios from 0% to 10%, were synthesized by flame spray pyrolysis (FSP), employing a single-step method. Ferrocene, being nontoxic and readily soluble in liquid hydrocarbons, was used as the iron source, while titanium tetraisopropoxide (TTIP) was [...] Read more.
Iron-doped titanium dioxide nanoparticles, with Fe/Ti atomic ratios from 0% to 10%, were synthesized by flame spray pyrolysis (FSP), employing a single-step method. Ferrocene, being nontoxic and readily soluble in liquid hydrocarbons, was used as the iron source, while titanium tetraisopropoxide (TTIP) was used as the precursor for TiO2. The general particle characterization and phase description were examined using ICP-OES, XRD, BET, and Raman spectroscopy, whereas the XPS technique was used to study the surface chemistry of the synthesized particles. For particle morphology, HRTEM with EELS and EDS analyses were used. Optical and magnetic properties were examined using UV–vis and SQUID, respectively. Iron doping to TiO2 nanoparticles promoted rutile phase formation, which was minor in the pure TiO2 particles. Iron-doped nanoparticles exhibited a uniform iron distribution within the particles. XPS and UV–vis results revealed that Fe2+ was dominant for lower iron content and Fe3+ was common for higher iron content and the iron-containing particles had a contracted band gap of ~1 eV lower than pure TiO2 particles with higher visible light absorption. SQUID results showed that doping TiO2 with Fe changed the material to be paramagnetic. The generated nanoparticles showed a catalytic effect for dye-degradation under visible light. Full article
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Article
Bi-Polymer Electrospun Nanofibers Embedding Ag3PO4/P25 Composite for Efficient Photocatalytic Degradation and Anti-Microbial Activity
Catalysts 2020, 10(7), 784; https://doi.org/10.3390/catal10070784 - 14 Jul 2020
Cited by 2 | Viewed by 1048
Abstract
Using a bi-polymer system comprising of transparent poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), a visible light active Ag3PO4/P25 composite was immobilized into the mats of polymeric electrospun nanofibers. After nanofibers synthesis, sacrificial PVP was removed, leaving behind rough [...] Read more.
Using a bi-polymer system comprising of transparent poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), a visible light active Ag3PO4/P25 composite was immobilized into the mats of polymeric electrospun nanofibers. After nanofibers synthesis, sacrificial PVP was removed, leaving behind rough surface nanofibers with easy access to Ag3PO4/P25 composite. The remarkable photocatalytic efficiency was attained using a PMMA and Ag3PO4/P25 weight ratio of 1:0.6. Methyl orange (MO) was used to visualize pollutant removal and exhibited stable removal kinetics up to five consecutive cycles under simulated daylight. Also, these polymeric nanofibers (NFs) revealed an important role in the destruction of microorganisms (E. coli), signifying their potential in water purification. A thin film fibrous mat was also used in a small bench scale plug flow reactor (PFR) for polishing of synthetic secondary effluent and the effects of inorganic salts were studied upon photocatalytic degradation in terms of total organic carbon (TOC) and turbidity removal. Lower flow rate (5 mL/h) resulted in maximum TOC and turbidity removal rates of 86% and 50%, respectively. Accordingly, effective Ag3PO4/P25 immobilization into an ideal support material and selectivity towards target pollutants could both enhance the efficiency of photocatalytic process under solar radiations without massive energy input. Full article
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Article
Analysis of Adsorption and Decomposition of Odour and Tar Components in Tobacco Smoke on Non-Woven Fabric-Supported Photocatalysts
Catalysts 2020, 10(3), 304; https://doi.org/10.3390/catal10030304 - 06 Mar 2020
Cited by 1 | Viewed by 3887
Abstract
The release of substantial amounts of toxicologically significant, irritant, and malodourous compounds during the complete combustion of tobacco can generate an unpleasant environment, especially indoors. Herein, we developed non-woven fabric-supported UV- and visible-light-responsive photocatalysts capable of adsorbing and decomposing the odour and tar [...] Read more.
The release of substantial amounts of toxicologically significant, irritant, and malodourous compounds during the complete combustion of tobacco can generate an unpleasant environment, especially indoors. Herein, we developed non-woven fabric-supported UV- and visible-light-responsive photocatalysts capable of adsorbing and decomposing the odour and tar components of tobacco smoke under irradiation with UV or visible light. The processes of odour component adsorption and subsequent decomposition under irradiation were evaluated in terms of colour changes in the catalytic system and by gas chromatography–mass spectrometry. By considering three different photocatalysts, namely TiO2, Fe(III)-grafted TiO2, and Cu(II)-grafted WO3, we assessed the magnitude of odour and tar component adsorption on the fabric fibres, as well as the decomposition of these species after specific visible light or UV irradiation periods. Considering the expansion of our technology for practical applications, the best results among the three tested materials were obtained for non-woven fabric-supported Fe/TiO2. We believe that our technology can be implemented in the design of interior decoration materials for creating a comfortable environment. Full article
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Article
Influence of the Facets of Bi24O31Br10 Nanobelts and Nanosheets on Their Photocatalytic Properties
Catalysts 2020, 10(2), 257; https://doi.org/10.3390/catal10020257 - 20 Feb 2020
Cited by 4 | Viewed by 767
Abstract
Bi24O31Br10 microcrystals composed of nanobelts and nanosheets with exposed (30-4) and (117) facets were synthesized by a simple hydrothermal method. The desired morphology and facets were obtained by adjusting the pH of the reaction system. Bi24O [...] Read more.
Bi24O31Br10 microcrystals composed of nanobelts and nanosheets with exposed (30-4) and (117) facets were synthesized by a simple hydrothermal method. The desired morphology and facets were obtained by adjusting the pH of the reaction system. Bi24O31Br10 nanobelts (BOB-NBs) with dominant (30-4) exposed facets were used for the photocatalytic degradation of tetracycline hydrochloride under visible light irradiation, with a degradation efficiency of up to 91% after 60 min of irradiation. The BOB-NBs possessed a higher charge separation and transfer efficiency, and showed less charge carrier recombination compared to the Bi24O31Br10 nanosheets (BOB-NSs), ascribed to a cooperative effect between the internal electric fields and surface active sites. A higher photocurrent response (2.6 times higher) was observed for BOB-NBs (12.8 μA cm−2) compared to that of BOB-NSs (4.9 μA cm−2). These findings are directional for a comprehensive understanding of the influence of the crystal facets of Bi24O31Br10 microcrystals on their photocatalytic activity and could help to guide the future design of high-performance photocatalytic materials. Full article
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Article
Metal-Free Enhanced Photocatalytic Activation of Dioxygen by g-C3N4 Doped with Abundant Oxygen-Containing Functional Groups for Selective N-Deethylation of Rhodamine B
Catalysts 2020, 10(1), 6; https://doi.org/10.3390/catal10010006 - 18 Dec 2019
Cited by 5 | Viewed by 985
Abstract
To develop highly efficient heterogeneous photocatalysts for the activation of dissolved oxygen is very interesting in the field of green degradation of organic pollutants. In the paper, oxygen atom doped g-C3N4 (O-g-C3N4) was prepared via a [...] Read more.
To develop highly efficient heterogeneous photocatalysts for the activation of dissolved oxygen is very interesting in the field of green degradation of organic pollutants. In the paper, oxygen atom doped g-C3N4 (O-g-C3N4) was prepared via a facile chemical oxidation of g-C3N4 by peroxymonosulfate. X-ray photoelectron spectroscopy analysis suggests the oxidative treatment of g-C3N4 by peroxymonosulfate evidently increased atomic percentage of oxygen on O-g-C3N4 surface to 6.9% as compared with 1.8% for g-C3N4. Meanwhile, the doped oxygen atom mainly existed as carbonyl and carboxyl groups. Optical characterization indicates the introduction of oxygen improved the response of O-g-C3N4 to visible light, and more obviously, separation of photo-generated h+-e. 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) probe measurement indicates the formation of O2•− was dramatically enhanced through activation of dioxygen by photo-generated electrons in the O-g-C3N4 photocatalytic system. Through high performance liquid chromatography (HPLC) and Liquid chromatography–mass spectrometry (LC-MS) analysis, it was found rhodamine B (RhB) photocatalytic degradation by O-g-C3N4 followed step by step N-deethylation reaction pathways induced by the formed O2•−, rather than the non-selective decomposition of the chromophore in RhB by other radicals, such as hydroxyl radicals. This study provides a facile method to develop oxygen atom doped g-C3N4 photocatalyst, and also clarifies its photocatalytic activation mechanism of molecular oxygen for N-deethylation reaction of RhB. Full article
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Article
Size-Controlled Synthesis of Pt Particles on TiO2 Surface: Physicochemical Characteristic and Photocatalytic Activity
Catalysts 2019, 9(11), 940; https://doi.org/10.3390/catal9110940 - 08 Nov 2019
Cited by 11 | Viewed by 1038
Abstract
Different TiO2 photocatalysts, i.e., commercial samples (ST-01 and P25 with minority of rutile phase), nanotubes, well-crystallized faceted particles of decahedral shape and mesoporous spheres, were used as supports for deposition of Pt nanoparticles (NPs). Size-controlled Pt NPs embedded in TiO2 were [...] Read more.
Different TiO2 photocatalysts, i.e., commercial samples (ST-01 and P25 with minority of rutile phase), nanotubes, well-crystallized faceted particles of decahedral shape and mesoporous spheres, were used as supports for deposition of Pt nanoparticles (NPs). Size-controlled Pt NPs embedded in TiO2 were successfully prepared by microemulsion and wet-impregnation methods. Obtained photocatalysts were characterized using XRD, TEM, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) specific surface area, DR/UV-vis and action spectrum analysis. The effect of deposition method, amount of Pt precursor and TiO2 properties on size, distribution, and chemical states of deposited Pt NPs were investigated. Finally, the correlations between the physicochemical properties and photocatalytic activities in oxidation and reduction reactions under UV and Vis light of different Pt-TiO2 photocatalysts were discussed. It was found that, regardless of preparation method, the photoactivity mainly depended on platinum and TiO2 morphology. In view of this, we claim that the tight control of NPs’ morphology allows us to design highly active materials with enhanced photocatalytic performance. Action spectrum analysis for the most active Pt-modified TiO2 sample showed that visible light-induced phenol oxidation is initiated by excitation of platinum surface plasmon, and photocatalytic activity analysis revealed that photoactivity depended strongly on morphology of the obtained Pt-modified TiO2 photocatalysts. Full article
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Article
A Comparative Study of Microcystin-LR Degradation by UV-A, Solar and Visible Light Irradiation Using Bare and C/N/S-Modified Titania
Catalysts 2019, 9(11), 877; https://doi.org/10.3390/catal9110877 - 23 Oct 2019
Cited by 6 | Viewed by 850
Abstract
In an endeavor to tackle environmental problems, the photodegradation of microcystin-LR (MC-LR), one of the most common and toxic cyanotoxins, produced by the cyanobacteria blooms, was examined using nanostructured TiO2 photocatalysts (anatase, brookite, anatase–brookite, and C/N/S co-modified anatase–brookite) under UV-A, solar and [...] Read more.
In an endeavor to tackle environmental problems, the photodegradation of microcystin-LR (MC-LR), one of the most common and toxic cyanotoxins, produced by the cyanobacteria blooms, was examined using nanostructured TiO2 photocatalysts (anatase, brookite, anatase–brookite, and C/N/S co-modified anatase–brookite) under UV-A, solar and visible light irradiation. The tailoring of TiO2 properties to hinder the electron–hole recombination and improve MC-LR adsorption on TiO2 surface was achieved by altering the preparation pH value. The highest photocatalytic efficiency was 97% and 99% with degradation rate of 0.002 mmol L−1 min−1 and 0.0007 mmol L−1 min−1 under UV and solar irradiation, respectively, using a bare TiO2 photocatalyst prepared at pH 10 with anatase to brookite ratio of ca. 1:2.5. However, the bare TiO2 samples were hardly active under visible light irradiation (<25%) due to a large band gap. Upon UV, solar and vis irradiation, the complete MC-LR degradation (100%) was obtained in the presence of C/N/S co-modified TiO2 with a degradation rate constant of 0.26 min−1, 0.11 min−1 and 0.04 min−1, respectively. It was proposed that the remarkable activity of co-modified TiO2 might originate from its mixed-phase composition, mesoporous structure, and non-metal co-modification. Full article
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Review

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Review
Computer Simulations of Photocatalytic Reactors
Catalysts 2021, 11(2), 198; https://doi.org/10.3390/catal11020198 - 03 Feb 2021
Viewed by 807
Abstract
Photocatalysis has been considered future technology for green energy conversion and environmental purification, including carbon dioxide reduction, water splitting, air/water treatment, and antimicrobial purposes. Although various photocatalysts with high activity and stability have already been found, the commercialization of photocatalytic processes seems to [...] Read more.
Photocatalysis has been considered future technology for green energy conversion and environmental purification, including carbon dioxide reduction, water splitting, air/water treatment, and antimicrobial purposes. Although various photocatalysts with high activity and stability have already been found, the commercialization of photocatalytic processes seems to be slow; it is thought that the difficulty in scaling up photocatalytic processes might be responsible. Research on the design of photocatalytic reactors using computer simulations has been recently intensive. The computer simulations involve various methods of hydrodynamics, radiation, and mass transport analysis, including the Monte Carlo method, the approximation approach–P1 model, and computational fluid dynamics as a complex simulation tool. This review presents all of these models, which might be efficiently used for the scaling-up of photocatalytic reactors. The challenging aspects and perspectives of computer simulation are also addressed for the future development of applied photocatalysis. Full article
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Review
Antiviral Effect of Visible Light-Sensitive CuxO/TiO2 Photocatalyst
Catalysts 2020, 10(9), 1093; https://doi.org/10.3390/catal10091093 - 21 Sep 2020
Cited by 8 | Viewed by 3676
Abstract
Photocatalysis is an effective technology for preventing the spread of pandemic-scale viruses. This review paper presents an overview of the recent progress in the development of an efficient visible light-sensitive photocatalyst, i.e., a copper oxide nanoclusters grafted titanium dioxide (CuxO/TiO2 [...] Read more.
Photocatalysis is an effective technology for preventing the spread of pandemic-scale viruses. This review paper presents an overview of the recent progress in the development of an efficient visible light-sensitive photocatalyst, i.e., a copper oxide nanoclusters grafted titanium dioxide (CuxO/TiO2). The antiviral CuxO/TiO2 photocatalyst is functionalised by a different mechanism in addition to the photocatalytic oxidation process. The CuxO nanocluster consists of the valence states of Cu(I) and Cu(II); herein, the Cu(I) species denaturalizes the protein of the virus, thereby resulting in significant antiviral properties even under dark conditions. Moreover, the Cu(II) species in the CuxO nanocluster serves as an electron acceptor through photo-induced interfacial charge transfer, which leads to the formation of an anti-virus Cu(I) species and holes with strong oxidation power in the valence band of TiO2 under visible-light irradiation. The antiviral function of the CuxO/TiO2 photocatalyst is maintained under indoor conditions, where light illumination is enabled during the day but not during the night; this is because the remaining active Cu(I) species works under dark conditions. The CuxO/TiO2 photocatalyst can thus be used to reduce the risk of virus infection by acting as an antiviral coating material. Full article
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Review
Water Depollution and Photo-Detoxification by Means of TiO2: Fluoroquinolone Antibiotics as a Case Study
Catalysts 2020, 10(6), 628; https://doi.org/10.3390/catal10060628 - 05 Jun 2020
Cited by 3 | Viewed by 696
Abstract
Photocatalysis by semiconductors is considered one of the most promising advanced oxidation processes (AOPs) and TiO2 is the most well-studied material for the removal of contaminants from the aquatic system. Over the last 20 years, pharmaceuticals have been the most investigated pollutants. [...] Read more.
Photocatalysis by semiconductors is considered one of the most promising advanced oxidation processes (AOPs) and TiO2 is the most well-studied material for the removal of contaminants from the aquatic system. Over the last 20 years, pharmaceuticals have been the most investigated pollutants. They re-enter the environment almost unmodified or slightly metabolized, especially in the aquatic environment, since the traditional urban wastewater treatment plants (WWTPs) are not able to abate them. Due to their continuous input, persistence in the environment, and unpleasant effects even at low concentrations, drugs are considered contaminants of emerging concern (ECs). Among these, we chose fluoroquinolone (FQ) antibiotics as an environmental probe for assessing the role of TiO2 photocatalysis in the degradation of recalcitrant pollutants under environmental conditions and detoxification of surface waters and wastewaters. Due to their widespread diffusion, their presence in the list of the most persistent pollutants, and because they have been deeply investigated and their multiform photochemistry is well-known, they are able to supply rich information, both chemical and toxicological, on all key steps of the oxidative degradation process. The present review article explores, in a non-exhaustive way, the relationship among pollution, toxicity and remediation through titanium dioxide photocatalysis, with particular attention to the toxicological aspect. By using FQs as the probe, in depth indications about the different phases of the process were obtained, and the results reported in this paper may be useful in the improvement of large-scale applications of this technology, and—through generally valid methods—they could be deployed to other pharmaceuticals and emerging recalcitrant contaminants. Full article
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