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Editorial

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4 pages, 197 KiB

Open AccessEditorial

Advanced Photocatalytic Materials for Environmental and Energy Applications

by Tongming Su and Xingwang Zhu

Materials 2023, 16(22), 7197; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16227197 - 17 Nov 2023

Cited by 1 | Viewed by 976

Abstract

With the development of modern society, environmental pollution and energy shortage have become the focus of worldwide attention [...] Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

Research

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15 pages, 4025 KiB

Open AccessArticle

Treatment of Mixture Pollutants with Combined Plasma Photocatalysis in Continuous Tubular Reactors with Atmospheric-Pressure Environment: Understanding Synergetic Effect Sources

by Lotfi Khezami and Aymen Amin Assadi

Materials 2023, 16(21), 6857; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16216857 - 25 Oct 2023

Cited by 2 | Viewed by 797

Abstract

This study investigates the pilot-scale combination of nonthermal plasma and photocatalysis for removing Toluene and dimethyl sulfur (DMDS), examining the influence of plasma energy and initial pollutant concentration on the performance and by-product formation in both pure compounds and mixtures. The results indicate [...] Read more.

This study investigates the pilot-scale combination of nonthermal plasma and photocatalysis for removing Toluene and dimethyl sulfur (DMDS), examining the influence of plasma energy and initial pollutant concentration on the performance and by-product formation in both pure compounds and mixtures. The results indicate a consistent 15% synergy effect, improving Toluene conversion rates compared to single systems. Ozone reduction and enhanced CO₂ selectivity were observed when combining plasma and photocatalysis. This process effectively treats pollutant mixtures, even those containing sulfur compounds. Furthermore, tests confirm nonthermal plasma’s in-situ regeneration of the photocatalytic surface, providing a constant synergy effect. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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15 pages, 10779 KiB

Open AccessEditor’s ChoiceArticle

Phosphorus-Doped Hollow Tubular g-C₃N₄ for Enhanced Photocatalytic CO₂ Reduction

by Manying Sun, Chuanwei Zhu, Su Wei, Liuyun Chen, Hongbing Ji, Tongming Su and Zuzeng Qin

Materials 2023, 16(20), 6665; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16206665 - 12 Oct 2023

Cited by 3 | Viewed by 1135

Abstract

Photocatalytic CO₂ reduction is a tactic for solving the environmental pollution caused by greenhouse gases. Herein, NH₄H₂PO₄ was added as a phosphorus source in the process of the hydrothermal treatment of melamine for the first time, and [...] Read more.

Photocatalytic CO₂ reduction is a tactic for solving the environmental pollution caused by greenhouse gases. Herein, NH₄H₂PO₄ was added as a phosphorus source in the process of the hydrothermal treatment of melamine for the first time, and phosphorus-doped hollow tubular g-C₃N₄ (x-P-HCN) was fabricated and used for photocatalytic CO₂ reduction. Here, 1.0-P-HCN exhibited the largest CO production rate of 9.00 μmol·g⁻¹·h⁻¹, which was 10.22 times higher than that of bulk g-C₃N₄. After doping with phosphorus, the light absorption range, the CO₂ adsorption capacity, and the specific surface area of the 1.0-P-HCN sample were greatly improved. In addition, the separation of photogenerated electron–hole pairs was enhanced. Furthermore, the phosphorus-doped g-C₃N₄ effectively activated the CO₂ adsorbed on the surface of phosphorus-doped g-C₃N₄ photocatalysts, which greatly enhanced the CO production rate of photocatalytic CO₂ reduction over that of g-C₃N₄. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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12 pages, 4335 KiB

Open AccessArticle

TiO₂ Nanotubes Decorated with Mo₂C for Enhanced Photoelectrochemical Water-Splitting Properties

by Siti Nurul Falaein Moridon, Khuzaimah Arifin, Mohamad Azuwa Mohamed, Lorna Jeffery Minggu, Rozan Mohamad Yunus and Mohammad B. Kassim

Materials 2023, 16(18), 6261; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16186261 - 18 Sep 2023

Cited by 4 | Viewed by 1008

Abstract

The presence of Ti³⁺ in the structure of TiO₂ nanotube arrays (NTs) has been shown to enhance the photoelectrochemical (PEC) water-splitting performance of these NTs, leading to improved results compared to pristine anatase TiO₂ NTs. To further improve the properties [...] Read more.

The presence of Ti³⁺ in the structure of TiO₂ nanotube arrays (NTs) has been shown to enhance the photoelectrochemical (PEC) water-splitting performance of these NTs, leading to improved results compared to pristine anatase TiO₂ NTs. To further improve the properties related to PEC performance, we successfully produced TiO₂ NTs using a two-step electrochemical anodization technique, followed by annealing at a temperature of 450 °C. Subsequently, Mo₂C was decorated onto the NTs by dip coating them with precursors at varying concentrations and times. The presence of anatase TiO₂ and Ti₃O₅ phases within the TiO₂ NTs was confirmed through X-ray diffraction (XRD) analysis. The TiO₂ NTs that were decorated with Mo₂C demonstrated a photocurrent density of approximately 1.4 mA cm⁻², a value that is approximately five times greater than the photocurrent density exhibited by the bare TiO₂ NTs, which was approximately 0.21 mA cm⁻². The observed increase in photocurrent density can be ascribed to the incorporation of Mo₂C as a cocatalyst, which significantly enhances the photocatalytic characteristics of the TiO₂ NTs. The successful deposition of Mo₂C onto the TiO₂ NTs was further corroborated by the characterization techniques utilized. The utilization of field emission scanning electron microscopy (FESEM) allowed for the observation of Mo₂C particles on the surface of TiO₂ NTs. To validate the composition and optical characteristics of the decorated NTs, X-ray photoelectron spectroscopy (XPS) and UV absorbance analysis were performed. This study introduces a potentially effective method for developing efficient photoelectrodes based on TiO₂ for environmentally sustainable hydrogen production through the use of photoelectrochemical water-splitting devices. The utilization of Mo₂C as a cocatalyst on TiO₂ NTs presents opportunities for the advancement of effective and environmentally friendly photoelectrochemical (PEC) systems. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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13 pages, 6081 KiB

Open AccessArticle

Theoretical and Experimental Study of the Photocatalytic Properties of ZnO Semiconductor Nanoparticles Synthesized by Prosopis laevigata

by Mizael Luque Morales, Priscy Alfredo Luque Morales, Manuel de Jesús Chinchillas Chinchillas, Víctor Manuel Orozco Carmona, Claudia Mariana Gómez Gutiérrez, Alfredo Rafael Vilchis Nestor and Rubén César Villarreal Sánchez

Materials 2023, 16(18), 6169; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16186169 - 12 Sep 2023

Cited by 1 | Viewed by 862

Abstract

In this work, the photocatalytic activity of nanoparticles (NPs) of zinc oxide synthetized by Prosopis laevigata as a stabilizing agent was evaluated in the degradation of methylene blue (MB) dye under UV radiation. The theoretical study of the photocatalytic degradation process was carried [...] Read more.

In this work, the photocatalytic activity of nanoparticles (NPs) of zinc oxide synthetized by Prosopis laevigata as a stabilizing agent was evaluated in the degradation of methylene blue (MB) dye under UV radiation. The theoretical study of the photocatalytic degradation process was carried out by a Langmuir–Hinshelwood–Hougen–Watson (LHHW) model. Zinc oxide nanoparticles were synthesized by varying the concentration of natural extract of Prosopis laevigata from 1, 2, and 4% (weight/volume), identifying the samples as ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. The characterization of the nanoparticles was carried out by Fourier transform infrared spectroscopy (FT-IR), where the absorption band for the Zn-O vibration at 400 cm⁻¹ was presented; by ultraviolet–visible spectroscopy (UV–vis) the value of the band gap was calculated, resulting in 2.80, 2.74 and 2.63 eV for the samples ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively; XRD analysis indicated that the nanoparticles have a hexagonal zincite crystal structure with an average crystal size of 55, 50, and 49 in the sample ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. The morphology observed by TEM showed that the nanoparticles had a hemispherical shape, and the ZnO_PL4% sample presented sizes ranging between 29 and 45 nm. The photocatalytic study showed a total degradation of the MB in 150, 120, and 60 min for the samples ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. Also, the model explains the experimental observation of the first-order kinetic model in the limit of low concentrations of dye, indicating the influence of the mass transfer processes. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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18 pages, 10869 KiB

Open AccessEditor’s ChoiceArticle

The Superiority of TiO₂ Supported on Nickel Foam over Ni-Doped TiO₂ in the Photothermal Decomposition of Acetaldehyde

by Beata Tryba, Piotr Miądlicki, Piotr Rychtowski, Maciej Trzeciak and Rafał Jan Wróbel

Materials 2023, 16(15), 5241; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16155241 - 26 Jul 2023

Cited by 3 | Viewed by 1165

Abstract

Acetaldehyde decomposition was performed under heating at a temperature range of 25–125 °C and UV irradiation on TiO₂ doped by metallic Ni powder and TiO₂ supported on nickel foam. The process was carried out in a high-temperature reaction chamber, “The Praying [...] Read more.

Acetaldehyde decomposition was performed under heating at a temperature range of 25–125 °C and UV irradiation on TiO₂ doped by metallic Ni powder and TiO₂ supported on nickel foam. The process was carried out in a high-temperature reaction chamber, “The Praying Mantis^TM”, with simultaneous in situ FTIR measurements and UV irradiation. Ni powder was added to TiO₂ in the quantity of 0.5 to 5.0 wt%. The photothermal measurements of acetaldehyde decomposition indicated that the highest yield of acetaldehyde conversion on TiO₂ and UV irradiation was obtained at 75 °C. The doping of nickel to TiO₂ did not increase its photocatalytic activity. Contrary to that, the application of nickel foam as a support for TiO₂ appeared to be highly advantageous because it increased the decomposition of acetaldehyde from 31 to 52% at 25 °C, and then to 85% at 100 °C in comparison with TiO₂ itself. At the same time, the mineralization of acetaldehyde to CO₂ doubled in the presence of nickel foam. However, oxidized nickel foam used as support for TiO₂ was detrimental. Most likely, different mechanisms of electron transfer between Ni–TiO₂ and NiO-TiO₂ occurred. The application of nickel foam greatly enhanced the separation of free carriers in TiO₂. As a consequence, high yields from the photocatalytic reactions were obtained. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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16 pages, 9825 KiB

Open AccessEditor’s ChoiceArticle

Hydrothermal Synthesis of MoS₂/SnS₂ Photocatalysts with Heterogeneous Structures Enhances Photocatalytic Activity

by Guansheng Ma, Zhigang Pan, Yunfei Liu, Yinong Lu and Yaqiu Tao

Materials 2023, 16(12), 4436; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16124436 - 16 Jun 2023

Cited by 8 | Viewed by 1635

Abstract

The use of solar photocatalysts to degrade organic pollutants is not only the most promising and efficient strategy to solve pollution problems today but also helps to alleviate the energy crisis. In this work, MoS₂/SnS₂ heterogeneous structure catalysts were prepared [...] Read more.

The use of solar photocatalysts to degrade organic pollutants is not only the most promising and efficient strategy to solve pollution problems today but also helps to alleviate the energy crisis. In this work, MoS₂/SnS₂ heterogeneous structure catalysts were prepared by a facile hydrothermal method, and the microstructures and morphologies of these catalysts were investigated using XRD, SEM, TEM, BET, XPS and EIS. Eventually, the optimal synthesis conditions of the catalysts were obtained as 180 °C for 14 h, with the molar ratio of molybdenum to tin atoms being 2:1 and the acidity and alkalinity of the solution adjusted by hydrochloric acid. TEM images of the composite catalysts synthesized under these conditions clearly show that the lamellar SnS₂ grows on the surface of MoS₂ at a smaller size; high-resolution TEM images show lattice stripe distances of 0.68 nm and 0.30 nm for the (002) plane of MoS₂ and the (100) plane of SnS₂, respectively. Thus, in terms of microstructure, it is confirmed that the MoS₂ and SnS₂ in the composite catalyst form a tight heterogeneous structure. The degradation efficiency of the best composite catalyst for methylene blue (MB) was 83.0%, which was 8.3 times higher than that of pure MoS₂ and 16.6 times higher than that of pure SnS₂. After four cycles, the degradation efficiency of the catalyst was 74.7%, indicating a relatively stable catalytic performance. The increase in activity could be attributed to the improved visible light absorption, the increase in active sites introduced at the exposed edges of MoS₂ nanoparticles and the construction of heterojunctions opening up photogenerated carrier transfer pathways and effective charge separation and transfer. This unique heterostructure photocatalyst not only has excellent photocatalytic performance but also has good cycling stability, which provides a simple, convenient and low-cost method for the photocatalytic degradation of organic pollutants. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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11 pages, 6180 KiB

Open AccessArticle

Highly Efficient and Exceptionally Durable Photooxidation Properties on Co₃O₄/g-C₃N₄ Surfaces

by Yelin Dai, Ziyi Feng, Kang Zhong, Jianfeng Tian, Guanyu Wu, Qing Liu, Zhaolong Wang, Yingjie Hua, Jinyuan Liu, Hui Xu and Xingwang Zhu

Materials 2023, 16(10), 3879; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16103879 - 22 May 2023

Cited by 1 | Viewed by 1151

Abstract

Water pollution is a significant social issue that endangers human health. The technology for the photocatalytic degradation of organic pollutants in water can directly utilize solar energy and has a promising future. A novel Co₃O₄/g-C₃N₄ type-II [...] Read more.

Water pollution is a significant social issue that endangers human health. The technology for the photocatalytic degradation of organic pollutants in water can directly utilize solar energy and has a promising future. A novel Co₃O₄/g-C₃N₄ type-II heterojunction material was prepared by hydrothermal and calcination strategies and used for the economical photocatalytic degradation of rhodamine B (RhB) in water. Benefitting the development of type-II heterojunction structure, the separation and transfer of photogenerated electrons and holes in 5% Co₃O₄/g-C₃N₄ photocatalyst was accelerated, leading to a degradation rate 5.8 times higher than that of pure g-C₃N₄. The radical capturing experiments and ESR spectra indicated that the main active species are •O₂⁻ and h⁺. This work will provide possible routes for exploring catalysts with potential for photocatalytic applications. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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9 pages, 1789 KiB

Open AccessArticle

Efficiency Improvement of Industrial Silicon Solar Cells by the POCl₃ Diffusion Process

by Xiaodong Xu, Wangping Wu and Qinqin Wang

Materials 2023, 16(5), 1824; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16051824 - 23 Feb 2023

Cited by 1 | Viewed by 1903

Abstract

To improve the efficiency of polycrystalline silicon solar cells, process optimization is a key technology in the photovoltaic industry. Despite the efficiency of this technique to be reproducible, economic, and simple, it presents a major inconvenience to have a heavily doped region near [...] Read more.

To improve the efficiency of polycrystalline silicon solar cells, process optimization is a key technology in the photovoltaic industry. Despite the efficiency of this technique to be reproducible, economic, and simple, it presents a major inconvenience to have a heavily doped region near the surface which induces a high minority carrier recombination. To limit this effect, an optimization of diffused phosphorous profiles is required. A “low-high-low” temperature step of the POCl₃ diffusion process was developed to improve the efficiency of industrial-type polycrystalline silicon solar cells. The low surface concentration of phosphorus doping of 4.54 × 10²⁰ atoms/cm³ and junction depth of 0.31 μm at a dopant concentration of N = 10¹⁷ atoms/cm³ were obtained. The open-circuit voltage and fill factor of solar cells increased up to 1 mV and 0.30%, compared with the online low-temperature diffusion process, respectively. The efficiency of solar cells and the power of PV cells were increased by 0.1% and 1 W, respectively. This POCl₃ diffusion process effectively improved the overall efficiency of industrial-type polycrystalline silicon solar cells in this solar field. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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13 pages, 2416 KiB

Open AccessEditor’s ChoiceArticle

Carbon Quantum Dots Accelerating Surface Charge Transfer of 3D PbBiO₂I Microspheres with Enhanced Broad Spectrum Photocatalytic Activity—Development and Mechanism Insight

by Ruyu Yan, Xinyi Liu, Haijie Zhang, Meng Ye, Zhenxing Wang, Jianjian Yi, Binxian Gu and Qingsong Hu

Materials 2023, 16(3), 1111; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16031111 - 27 Jan 2023

Cited by 4 | Viewed by 2016

Abstract

The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) [...] Read more.

The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) modified PbBiO₂I photocatalyst were synthesized for the first time through an in-situ ionic liquid-induced method. The bridging function of 1-butyl-3-methylimidazolium iodide ([Bmim]I) guarantees the even dispersion of CQDs around PbBiO₂I surface, for synchronically overcoming the above drawbacks and markedly promoting the degradation efficiency of organic contaminants: (i) CQDs decoration harness solar photons in the near-infrared region; (ii) particular delocalized conjugated construction of CQDs strength via the utilization of photo-induced carriers; (iii) π–π interactions increase the contact between catalyst and organic molecules. Benefiting from these distinguished features, the optimized CQDs/PbBiO₂I nanocomposite displays significantly enhanced photocatalytic performance towards the elimination of rhodamine B and ciprofloxacin under visible/near-infrared light irradiation. The spin-trapping ESR analysis demonstrates that CQDs modification can boost the concentration of reactive oxygen species (O₂^•−). Combined with radicals trapping tests, valence-band spectra, and Mott–Schottky results, a possible photocatalytic mechanism is proposed. This work establishes a significant milestone in constructing CQDs-modified, bismuth-based catalysts for solar energy conversion applications. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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Review

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17 pages, 4429 KiB

Open AccessReview

Recent Advances in Phase-Engineered Photocatalysts: Classification and Diversified Applications

by Jianjian Yi, Guoxiang Zhang, Yunzhe Wang, Wanyue Qian and Xiaozhi Wang

Materials 2023, 16(11), 3980; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16113980 - 26 May 2023

Cited by 4 | Viewed by 1227

Abstract

Phase engineering is an emerging strategy for tuning the electronic states and catalytic functions of nanomaterials. Great interest has recently been captured by phase-engineered photocatalysts, including the unconventional phase, amorphous phase, and heterophase. Phase engineering of photocatalytic materials (including semiconductors and cocatalysts) can [...] Read more.

Phase engineering is an emerging strategy for tuning the electronic states and catalytic functions of nanomaterials. Great interest has recently been captured by phase-engineered photocatalysts, including the unconventional phase, amorphous phase, and heterophase. Phase engineering of photocatalytic materials (including semiconductors and cocatalysts) can effectively affect the light absorption range, charge separation efficiency, or surface redox reactivity, resulting in different catalytic behavior. The applications for phase-engineered photocatalysts are widely reported, for example, hydrogen evolution, oxygen evolution, CO₂ reduction, and organic pollutant removal. This review will firstly provide a critical insight into the classification of phase engineering for photocatalysis. Then, the state-of-the-art development of phase engineering toward photocatalytic reactions will be presented, focusing on the synthesis and characterization methodologies for unique phase structure and the correlation between phase structure and photocatalytic performance. Finally, personal understanding of the current opportunities and challenges of phase engineering for photocatalysis will also be provided. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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22 pages, 1860 KiB

Open AccessReview

An Overview of Recent Developments in Improving the Photocatalytic Activity of TiO₂-Based Materials for the Treatment of Indoor Air and Bacterial Inactivation

by Achraf Amir Assadi, Oussama Baaloudj, Lotfi Khezami, Naoufel Ben Hamadi, Lotfi Mouni, Aymen Amine Assadi and Achraf Ghorbal

Materials 2023, 16(6), 2246; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16062246 - 10 Mar 2023

Cited by 8 | Viewed by 1816

Abstract

Indoor air quality has become a significant public health concern. The low cost and high efficiency of photocatalytic technology make it a natural choice for achieving deep air purification. Photocatalysis procedures have been widely investigated for environmental remediation, particularly for air treatment. Several [...] Read more.

Indoor air quality has become a significant public health concern. The low cost and high efficiency of photocatalytic technology make it a natural choice for achieving deep air purification. Photocatalysis procedures have been widely investigated for environmental remediation, particularly for air treatment. Several semiconductors, such as TiO₂, have been used for photocatalytic purposes as catalysts, and they have earned a lot of interest in the last few years owing to their outstanding features. In this context, this review has collected and discussed recent studies on advances in improving the photocatalytic activity of TiO₂-based materials for indoor air treatment and bacterial inactivation. In addition, it has elucidated the properties of some widely used TiO₂-based catalysts and their advantages in the photocatalytic process as well as improved photocatalytic activity using doping and heterojunction techniques. Current publications about various combined catalysts have been summarized and reviewed to emphasize the significance of combining catalysts to increase air treatment efficiency. Besides, this paper summarized works that used these catalysts to remove volatile organic compounds (VOCs) and microorganisms. Moreover, the reaction mechanism has been described and summarized based on literature to comprehend further pollutant elimination and microorganism inactivation using photocatalysis. This review concludes with a general opinion and an outlook on potential future research topics, including viral disinfection and other hazardous gases. Full article

(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)

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