Research

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15 pages, 6378 KiB

Open AccessFeature PaperArticle

Perovskite Zinc Titanate Photocatalysts Synthesized by the Sol–Gel Method and Their Application in the Photocatalytic Degradation of Emerging Contaminants

by Wei-Yu Chen, Ching-Ping Wang, Po-Chou Chen, Kun-Yi Andrew Lin, Surajit Ghosh, Chao-Wei Huang and Van-Huy Nguyen

Catalysts 2021, 11(7), 854; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11070854 - 16 Jul 2021

Cited by 22 | Viewed by 3635

Abstract

In this study, perovskite ZnTiO₃ photocatalysts were fabricated by the sol–gel method. The photocatalytic capability was verified by the degradation of the emerging contaminant, the antibiotic amoxicillin (AMX). For the preparation, the parameters of the calcination temperature and the additional amount of [...] Read more.

In this study, perovskite ZnTiO₃ photocatalysts were fabricated by the sol–gel method. The photocatalytic capability was verified by the degradation of the emerging contaminant, the antibiotic amoxicillin (AMX). For the preparation, the parameters of the calcination temperature and the additional amount of polyvinylpyrrolidone (PVP) and ammonia are discussed, including the calcining temperature (500, 600, 700, 800 °C), the volume of ammonia (750, 1500, 3000 μL), and the weight of PVP (3 g and 5 g). The prepared perovskite ZnTiO₃ was characterized by XRD, FESEM, BET, and UV-Vis. It is shown that the perovskite ZnTiO₃ photocatalysts are structurally rod-like and ultraviolet light-responsive. Consequently, the synthesis conditions for fabricating the perovskite ZnTiO₃ photocatalysts with the highest photocatalytic performance were a calcining temperature of 700 °C, an additional ammonia amount of 1500 μL, and added PVP of 5 g. Moreover, the photocatalytic degradation of perovskite ZnTiO₃ photocatalysts on other pollutants, including the antibiotic tetracycline (TC), methyl orange (MO), and methylene blue (MB) dyes, was also examined. This provides the basis for the application of perovskite ZnTiO₃ as a photocatalyst to decompose emerging contaminants and organic pollutants in wastewater treatment. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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19 pages, 4784 KiB

Open AccessArticle

Manipulating the Structure and Characterization of Sr_1−xLa_xTiO₃ Nanocubes toward the Photodegradation of 2-Naphthol under Artificial Solar Light

by Minh-Vien Le, Ngoc-Quoc-Duy Vo, Quoc-Cuong Le, Vy Anh Tran, Thi-Que-Phuong Phan, Chao-Wei Huang and Van-Huy Nguyen

Catalysts 2021, 11(5), 564; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050564 - 28 Apr 2021

Cited by 20 | Viewed by 2445

Abstract

Effective La-doped SrTiO₃ (Sr_1−xLa_xTiO₃, x = 0–0.1 mol.% La-doped) nanocubes were successfully synthesized by a hydrothermal method. The influence of different La dopant concentrations on the physicochemical properties of the host structure of SrTiO₃ was [...] Read more.

Effective La-doped SrTiO₃ (Sr_1−xLa_xTiO₃, x = 0–0.1 mol.% La-doped) nanocubes were successfully synthesized by a hydrothermal method. The influence of different La dopant concentrations on the physicochemical properties of the host structure of SrTiO₃ was fully characterized. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed that the Sr²⁺ in the crystal lattice of SrTiO₃ was substituted by La³⁺. As a result, the absorption region of the Sr_1−xLa_xTiO₃ could be extended to visible light. Scanning electron microscopy (SEM) images confirmed that their morphologies are associated with an increased surface area and an increased La-doping concentration. The decrease in the photoluminescence (PL) intensity of the dopant samples showed more defect levels created by the dopant La⁺³ cations in the SrTiO₃ structure. The photocatalytic activities of Sr_1−xLa_xTiO₃ were evaluated with regard to the degradation of 2-naphthol at typical conditions under artificial solar light. Among the candidates, Sr_0.95La_0.05TiO₃ exhibited the highest photocatalytic performance for the degradation of 2-naphthol, which reached 92% degradation efficiency, corresponding to a 0.0196 min⁻¹ degradation rate constant, within 180 minutes of irradiation. Manipulating the structure of Sr_1−xLa_xTiO₃ nanocubes could produce a more effective and stable degradation efficiency than their parent compound, SrTiO₃. The parameters remarkably influence the Sr_1−xLa_xTiO₃ nanocubes’ structure, and their degradation efficiencies were also studied. Undoubtedly, substantial breakthroughs of Sr_1−xLa_xTiO₃ nanocube photocatalysts toward the treatment of organic contaminants from industrial wastewater are expected shortly. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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20 pages, 2780 KiB

Open AccessArticle

CO₂ Hydrogenation to Methane over Ni-Catalysts: The Effect of Support and Vanadia Promoting

by Izabela S. Pieta, Agnieszka Lewalska-Graczyk, Pawel Kowalik, Katarzyna Antoniak-Jurak, Mikolaj Krysa, Anna Sroka-Bartnicka, Arkadiusz Gajek, Wojciech Lisowski, Dusan Mrdenovic, Piotr Pieta, Robert Nowakowski, Agata Lew and Ewa M. Serwicka

Catalysts 2021, 11(4), 433; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040433 - 28 Mar 2021

Cited by 18 | Viewed by 4692

Abstract

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods are developed to target the “closed carbon cycle”. The catalysts supported on different metal oxides were characterized by XRD, XPS, Raman, UV-Vis, temperature-programmed techniques; then, they were tested in CO₂ hydrogenation [...] Read more.

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods are developed to target the “closed carbon cycle”. The catalysts supported on different metal oxides were characterized by XRD, XPS, Raman, UV-Vis, temperature-programmed techniques; then, they were tested in CO₂ hydrogenation at 1 bar. Moreover, the V₂O₅ promotion was studied for Ni/Al₂O₃ catalyst. The precisely designed hydrotalcite-derived catalyst and vanadia-promoted Ni-catalysts deliver exceptional conversions for the studied processes, presenting high durability and selectivity, outperforming the best-known catalysts. The equilibrium conversion was reached at temperatures around 623 K, with the primary product of reaction CH₄ (>97% CH₄ yield). Although the Ni loading in hydrotalcite-derived NiWP is lower by more than 40%, compared to reference NiR catalyst and available commercial samples, the activity increases for this sample, reaching almost equilibrium values (GHSV = 1.2 × 10⁴ h^–1, 1 atm, and 293 K). Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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16 pages, 2483 KiB

Open AccessFeature PaperArticle

Visible-Light Photocatalyst to Remove Indoor Ozone under Ambient Condition

by Jia Quan Su, Yi-Chun Chang and Jeffrey C. S. Wu

Catalysts 2021, 11(3), 383; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11030383 - 16 Mar 2021

Viewed by 2143

Abstract

Ozone is a kind of hazardous gas in indoor areas and needs to be removed in order to protect the human respiratory system. Previous methods include physical adsorption, thermal treatment, electromagnetic radiation removal, catalysis and photocatalysis. However, they all have limited effects. This [...] Read more.

Ozone is a kind of hazardous gas in indoor areas and needs to be removed in order to protect the human respiratory system. Previous methods include physical adsorption, thermal treatment, electromagnetic radiation removal, catalysis and photocatalysis. However, they all have limited effects. This research introduced a novel milestone to remove indoor ozone by utilizing visible light photocatalysis technique under ambient condition. The modified sol–gel method was applied to prepare photocatalysts, strontium titanate (SrTiO₃) and rhodium-doped strontium titanate (SrTiO₃:Rh). In addition, the SrTiO₃:Rh was further immersed in N3 dye to improve its photocatalytic performance. Batch system and continuous-flow system were used to quantify the removal rate of ozone and to measure the conversions of ozone, respectively. The results showed that SrTiO₃:Rh possessed a higher ozone removal rate under a visible light condition compared with a commercial P25 TiO₂ catalyst. In addition, SrTiO₃:Rh based catalysts can also successfully perform visible light ozone photodecomposition in the continuous ozone flow system. Note that current ozone converters in aircraft utilize thermal-catalysts, which can only be operated at high temperature. This research reveals a promising catalysts and photo process, which can possibly replace the current aircraft ozone converters with visible-light driven converters, and boast higher performance under ambient condition. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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15 pages, 5236 KiB

Open AccessArticle

The Effects of Promoter Cs Loading on the Hydrogen Production from Ammonia Decomposition Using Ru/C Catalyst in a Fixed-Bed Reactor

by Yen-Ling Chen, Chin-Fang Juang and Yen-Cho Chen

Catalysts 2021, 11(3), 321; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11030321 - 02 Mar 2021

Cited by 12 | Viewed by 3507

Abstract

The hydrogen production from ammonia decomposition on commercial 5 wt.% Ru/C (C: activated carbon) catalyst with different cesium (Cs) loadings at lower temperatures of 325–400 °C in the fixed-bed reactor was experimentally investigated. Based on the parameters used in this work, the results [...] Read more.

The hydrogen production from ammonia decomposition on commercial 5 wt.% Ru/C (C: activated carbon) catalyst with different cesium (Cs) loadings at lower temperatures of 325–400 °C in the fixed-bed reactor was experimentally investigated. Based on the parameters used in this work, the results showed that the ammonia conversion at 350 °C is increased with the increasing Cs/Ru molar ratio, and it reaches its maximum value at the Cs/Ru molar ratio of 4.5. After that, it is rapidly decreased with a further increase of Cs/Ru molar ratio, and it is even smaller than that of the pure Ru/C case at the Cs/Ru molar ratio of 6. The Cs promotion at the lower Cs/Ru molar ratios may be due to the so-called “hot ring promotion”. The possible mechanisms for Cs effects on the ammonia conversion at higher Cs/Ru molar ratio are discussed. At optimum Cs loading, the results showed that all the ammonia conversions at 400 °C are near 100% for the GHSV (gas hourly space velocity) from 48,257 to 241,287 mL/(h·g_cat). Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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21 pages, 10242 KiB

Open AccessArticle

Synthesis of N-rGO-MWCNT/CuCrO₂ Catalyst for the Bifunctional Application of Hydrogen Evolution Reaction and Electrochemical Detection of Bisphenol-A

by Subramanian Sakthinathan, Arjunan Karthi Keyan, Ramachandran Rajakumaran, Shen-Ming Chen, Te-Wei Chiu, Chaofang Dong and Sivaramakrishnan Vinothini

Catalysts 2021, 11(3), 301; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11030301 - 25 Feb 2021

Cited by 16 | Viewed by 2591

Abstract

A glassy carbon electrode (GCE) coated with delafossite CuCrO₂ loading on the nitrogen-doped reduced graphene oxide (N-rGO) and multiwalled carbon nanotubes (MWCNT) composite (N-rGO-MWCNT/CuCrO₂) was applied to the hydrogen evolution reaction and Bisphenol-A (BPA) detection. First, the N-rGO-MWCNT composite was [...] Read more.

A glassy carbon electrode (GCE) coated with delafossite CuCrO₂ loading on the nitrogen-doped reduced graphene oxide (N-rGO) and multiwalled carbon nanotubes (MWCNT) composite (N-rGO-MWCNT/CuCrO₂) was applied to the hydrogen evolution reaction and Bisphenol-A (BPA) detection. First, the N-rGO-MWCNT composite was prepared by in situ chemical reduction with caffeic acid as a reducing agent. Then, CuCrO₂ was accumulated on the N-rGO-MWCNT surface to form N-rGO-MWCNT/CuCrO₂ composite. The morphology structure of the N-rGO-MWCNT/ CuCrO₂ composite was analyzed by different characterization techniques. Besides, the GCE/N-rGO-MWCNT/CuCrO₂ composite electrode was investigated for hydrogen evolution reaction (HER), which shows an excellent electrocatalytic activity with a low over-potential, increasing reduction current, and a small Tafel slope of 62 mV·dec⁻¹ at 10 mA·cm⁻² with long-term stability. Moreover, the electrochemical determination of BPA was in the range of 0.1-110 µM, and low detection limit of 0.033 µM (S/N = 3) with a higher sensitivity of 1.3726 µA µM⁻¹ cm⁻². Furthermore, the prepared GCE/N-rGO-MWCNT/CuCrO₂ electrode shows effective detection of BPA in food samples with acceptable recoveries. Hence, the finding of GCE/N-rGO-MWCNT/CuCrO₂ can be observed as an impressive catalyst to the electrocatalytic activity of HER and BPA oxidation. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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Review

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14 pages, 2622 KiB

Open AccessFeature PaperReview

Photocatalytic Inactivation of Viruses Using Graphitic Carbon Nitride-Based Photocatalysts: Virucidal Performance and Mechanism

by Vasudha Hasija, Shilpa Patial, Pardeep Singh, Van-Huy Nguyen, Quyet Van Le, Vijay Kumar Thakur, Chaudhery Mustansar Hussain, Rangabhashiyam Selvasembian, Chao-Wei Huang, Sourbh Thakur and Pankaj Raizada

Catalysts 2021, 11(12), 1448; https://doi.org/10.3390/catal11121448 - 28 Nov 2021

Cited by 18 | Viewed by 2596

Abstract

The prevalence of lethal viral infections necessitates the innovation of novel disinfection techniques for contaminated surfaces, air, and wastewater as significant transmission media of disease. The instigated research has led to the development of photocatalysis as an effective renewable solar-driven technology relying on [...] Read more.

The prevalence of lethal viral infections necessitates the innovation of novel disinfection techniques for contaminated surfaces, air, and wastewater as significant transmission media of disease. The instigated research has led to the development of photocatalysis as an effective renewable solar-driven technology relying on the reactive oxidative species, mainly hydroxyl (OH^●) and superoxide (O₂^●⁻) radicals, for rupturing the capsid shell of the virus and loss of pathogenicity. Metal-free graphitic carbon nitride (g-C₃N₄), which possesses a visible light active bandgap structure, low toxicity, and high thermal stability, has recently attracted attention for viral inactivation. In addition, g-C₃N₄-based photocatalysts have also experienced a renaissance in many domains, including environment, energy conversion, and biomedical applications. Herein, we discuss the three aspects of the antiviral mechanism, intending to highlight the advantages of photocatalysis over traditional viral disinfection techniques. The sole agenda of the review is to summarize the significant research on g-C₃N₄-based photocatalysts for viral inactivation by reactive oxidative species generation. An evaluation of the photocatalysis operational parameters affecting viral inactivation kinetics is presented. An overview of the prevailing challenges and sustainable solutions is presented to fill in the existing knowledge gaps. Given the merits of graphitic carbon nitride and the heterogeneous photocatalytic viral inactivation mechanism, we hope that further research will contribute to preventing the ongoing Coronavirus pandemic and future calamities. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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23 pages, 32731 KiB

Open AccessReview

Low-Dimensional Nanostructured Photocatalysts for Efficient CO₂ Conversion into Solar Fuels

by Hossam A. E. Omr, Mark W. Horn and Hyeonseok Lee

Catalysts 2021, 11(4), 418; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040418 - 25 Mar 2021

Cited by 18 | Viewed by 3279

Abstract

The ongoing energy crisis and global warming caused by the massive usage of fossil fuels and emission of CO₂ into atmosphere continue to motivate researchers to investigate possible solutions. The conversion of CO₂ into value-added solar fuels by photocatalysts has been [...] Read more.

The ongoing energy crisis and global warming caused by the massive usage of fossil fuels and emission of CO₂ into atmosphere continue to motivate researchers to investigate possible solutions. The conversion of CO₂ into value-added solar fuels by photocatalysts has been suggested as an intriguing solution to simultaneously mitigate global warming and provide a source of energy in an environmentally friendly manner. There has been considerable effort for nearly four decades investigating the performance of CO₂ conversion by photocatalysts, much of which has focused on structure or materials modification. In particular, the application of low-dimensional structures for photocatalysts is a promising pathway. Depending on the materials and fabrication methods, low-dimensional nanomaterials can be formed in zero dimensional structures such as quantum dots, one-dimensional structures such as nanowires, nanotubes, nanobelts, and nanorods, and two-dimensional structures such as nanosheets and thin films. These nanostructures increase the effective surface area and possess unique electrical and optical properties, including the quantum confinement effect in semiconductors or the localized surface plasmon resonance effect in noble metals at the nanoscale. These unique properties can play a vital role in enhancing the performance of photocatalytic CO₂ conversion into solar fuels by engineering the nanostructures. In this review, we provide an overview of photocatalytic CO₂ conversion and especially focus on nanostructured photocatalysts. The fundamental mechanism of photocatalytic CO₂ conversion is discussed and recent progresses of low-dimensional photocatalysts for efficient conversion of CO₂ into solar fuels are presented. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Materials toward Renewable Energy and the Removal of Environmental Pollutants)

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