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14 pages, 5450 KiB

Open AccessArticle

First Principle Study on the Z-Type Characteristic Modulation of GaN/g-C₃N₄ Heterojunction

by Meng-Yao Dai, Xu-Cai Zhao, Bo-Cheng Lei, Yi-Neng Huang, Li-Li Zhang, Hai Guo and Hua-Gui Wang

Molecules 2024, 29(22), 5355; https://doi.org/10.3390/molecules29225355 - 14 Nov 2024

Viewed by 347

Abstract

This study investigates the stability, electronic structure, and optical properties of the GaN/g-C₃N₄ heterojunction using the plane wave super-soft pseudopotential method based on first principles. Additionally, an external electric field is employed to modulate the band structure and optical properties [...] Read more.

This study investigates the stability, electronic structure, and optical properties of the GaN/g-C₃N₄ heterojunction using the plane wave super-soft pseudopotential method based on first principles. Additionally, an external electric field is employed to modulate the band structure and optical properties of GaN/g-C₃N₄. The computational results demonstrate that this heterojunction possesses a direct band gap and is classified as type II heterojunction, where the intrinsic electric field formed at the interface effectively suppresses carrier recombination. When the external electric field intensity (E) falls below −0.1 V/Å and includes −0.1 V/Å, or exceeds 0.2 V/Å, the heterojunction undergoes a transition from a type II structure to the superior Z-scheme, leading to a significant enhancement in the rate of separation of photogenerated carriers and an augmentation in its redox capability. Furthermore, the introduction of a positive electric field induces a redshift in the absorption spectrum, effectively broadening the light absorption range of the heterojunction. The aforementioned findings demonstrate that the optical properties of GaN/g-C₃N₄ can be precisely tuned by applying an external electric field, thereby facilitating its highly efficient utilization in the field of photocatalysis. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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17 pages, 3787 KiB

Open AccessArticle

The Influence of Heat Treatment on the Photoactivity of Amine-Modified Titanium Dioxide in the Reduction of Carbon Dioxide

by Iwona Pełech, Piotr Staciwa, Daniel Sibera, Konrad Sebastian Sobczuk, Wiktoria Majewska, Ewelina Kusiak-Nejman, Antoni W. Morawski, Kaiying Wang and Urszula Narkiewicz

Molecules 2024, 29(18), 4348; https://doi.org/10.3390/molecules29184348 - 13 Sep 2024

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Abstract

Modification of titanium dioxide using ethylenediamine (EDA), diethylamine (DEA), and triethylamine (TEA) has been studied. As the reference material, titanium dioxide prepared by the sol–gel method using titanium(IV) isopropoxide as a precursor was applied. The preparation procedure involved heat treatment in the microwave [...] Read more.

Modification of titanium dioxide using ethylenediamine (EDA), diethylamine (DEA), and triethylamine (TEA) has been studied. As the reference material, titanium dioxide prepared by the sol–gel method using titanium(IV) isopropoxide as a precursor was applied. The preparation procedure involved heat treatment in the microwave reactor or in the high-temperature furnace. The obtained samples have been characterized in detail. The phase composition was determined through the X-ray diffraction method, and the average crystallite size was calculated based on it. Values for specific surface areas and the total pore volumes were calculated based on the isotherms obtained through the low-temperature nitrogen adsorption method. The bang gap energy was estimated based on Tauc’s plots. The influence of the type and content of amine, as well as heat treatment on the photocatalytic activity of modified titanium dioxide in the photocatalytic reduction of carbon dioxide, was determined and discussed. It was clear that, regardless of the amount and content of amine introduced, the higher photoactivity characterized the samples prepared in the microwave reactor. The highest amounts of hydrogen, carbon monoxide, and methane have been achieved using triethylamine-modified titanium dioxide. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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28 pages, 15432 KiB

Open AccessArticle

MgO Nanoparticles as a Promising Photocatalyst towards Rhodamine B and Rhodamine 6G Degradation

by Maria-Anna Gatou, Natalia Bovali, Nefeli Lagopati and Evangelia A. Pavlatou

Molecules 2024, 29(18), 4299; https://doi.org/10.3390/molecules29184299 - 11 Sep 2024

Viewed by 1116

Abstract

The increasing global requirement for clean and safe drinking water has necessitated the development of efficient methods for the elimination of organic contaminants, especially dyes, from wastewater. This study reports the synthesis of magnesium oxide (MgO) nanoparticles via a simple precipitation approach and [...] Read more.

The increasing global requirement for clean and safe drinking water has necessitated the development of efficient methods for the elimination of organic contaminants, especially dyes, from wastewater. This study reports the synthesis of magnesium oxide (MgO) nanoparticles via a simple precipitation approach and their thorough characterization using various techniques, including XRD, FT-IR, XPS, TGA, DLS, and FESEM. Synthesized MgO nanoparticles’ photocatalytic effectiveness was evaluated towards rhodamine B and rhodamine 6G degradation under both UV and visible light irradiation. The results indicated that the MgO nanoparticles possess a face-centered cubic structure with enhanced crystallinity and purity, as well as an average crystallite size of approximately 3.20 nm. The nanoparticles demonstrated a significant BET surface area (52 m²/g) and a bandgap value equal to 5.27 eV. Photocatalytic experiments indicated complete degradation of rhodamine B dye under UV light within 180 min and 83.23% degradation under visible light. For rhodamine 6G, the degradation efficiency was 92.62% under UV light and 38.71% under visible light, thus verifying the MgO catalyst’s selectivity towards degradation of rhodamine B dye. Also, reusability of MgO was investigated for five experimental photocatalytic trials with very promising results, mainly against rhodamine B. Scavenging experiments confirmed that •OH radicals were the major reactive oxygen species involved in the photodegradation procedure, unraveling the molecular mechanism of the photocatalytic efficiency of MgO. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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14 pages, 3298 KiB

Open AccessArticle

Boosting the Activation of Molecular Oxygen and the Degradation of Rhodamine B in Polar-Functional-Group-Modified g-C₃N₄

by Jing Chen, Minghua Yang, Hongjiao Zhang, Yuxin Chen, Yujie Ji, Ruohan Yu and Zhenguo Liu

Molecules 2024, 29(16), 3836; https://doi.org/10.3390/molecules29163836 - 13 Aug 2024

Viewed by 897

Abstract

Molecular oxygen activation often suffers from high energy consumption and low efficiency. Developing eco-friendly and effective photocatalysts remains a key challenge for advancing green molecular oxygen activation. Herein, graphitic carbon nitride (g-C₃N₄) with abundant hydroxyl groups (HCN) was synthesized [...] Read more.

Molecular oxygen activation often suffers from high energy consumption and low efficiency. Developing eco-friendly and effective photocatalysts remains a key challenge for advancing green molecular oxygen activation. Herein, graphitic carbon nitride (g-C₃N₄) with abundant hydroxyl groups (HCN) was synthesized to investigate the relationship between these polar groups and molecular oxygen activation. The advantage of the hydroxyl group modification of g-C₃N₄ included narrower interlayer distances, a larger specific surface area and improved hydrophilicity. Various photoelectronic measurements revealed that the introduced hydroxyl groups reduced the charge transfer resistance of HCN, resulting in accelerated charge separation and migration kinetics. Therefore, the optimal HCN-90 showed the highest activity for Rhodamine B photodegradation with a reaction time of 30 min and an apparent rate constant of 0.125 min⁻¹, surpassing most other g-C₃N₄ composites. This enhanced activity was attributed to the adjusted band structure achieved through polar functional group modification. The modification of polar functional groups could alter the energy band structure of photocatalysts, narrow band gap, enhance visible-light absorption, and improve photogenerated carrier separation efficiency. This work highlights the significant potential of polar functional groups in tuning the structure of g-C₃N₄ to enhance efficient molecular oxygen activation. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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19 pages, 3534 KiB

Open AccessArticle

Modulation of Electronic Availability in g-C₃N₄ Using Nickel (II), Manganese (II), and Copper (II) to Enhance the Disinfection and Photocatalytic Properties

by Angie V. Lasso-Escobar, Elkin Darío C. Castrillon, Jorge Acosta, Sandra Navarro, Estefanía Correa-Penagos, John Rojas and Yenny P. Ávila-Torres

Molecules 2024, 29(16), 3775; https://doi.org/10.3390/molecules29163775 - 9 Aug 2024

Viewed by 794

Abstract

Carbon nitrides can form coordination compounds or metallic oxides in the presence of transition metals, depending on the reaction conditions. By adjusting the pH to basic levels for mild synthesis with metals, composites like g-C₃N₄-M(OH)_x (where M represents [...] Read more.

Carbon nitrides can form coordination compounds or metallic oxides in the presence of transition metals, depending on the reaction conditions. By adjusting the pH to basic levels for mild synthesis with metals, composites like g-C₃N₄-M(OH)_x (where M represents metals) were obtained for nickel (II) and manganese (II), while copper (II) yielded coordination compounds such as Cu-g-C₃N₄. These materials underwent spectroscopic and electrochemical characterization, revealing their photocatalytic potential to generate superoxide anion radicals—a feature consistent across all metals. Notably, the copper coordination compound also produced significant hydroxyl radicals. Leveraging this catalytic advantage, with band gap energy in the visible region, all compounds were activated to disinfect E. coli bacteria, achieving total disinfection with Cu-g-C₃N₄. The textural properties influence the catalytic performance, with copper’s stabilization as a coordination compound enabling more efficient activity compared to the other metals. Additionally, the determination of radicals generated under light in the presence of dicloxacillin supported the proposed mechanism and highlighted the potential for degrading organic molecules with this new material, alongside its disinfectant properties. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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17 pages, 5825 KiB

Open AccessArticle

First-Principles Study on Janus-Structured Sc₂CX₂/Sc₂CY₂ (X, Y = F, Cl, Br) Heterostructures for Solar Energy Conversion

by Xin He, Yanan Wu, Jia Luo, Xianglin Dai, Jun Song and Yong Tang

Molecules 2024, 29(12), 2898; https://doi.org/10.3390/molecules29122898 - 18 Jun 2024

Viewed by 742

Abstract

Two-dimensional van der Waals heterostructures have good application prospects in solar energy conversion due to their excellent optoelectronic performance. In this work, the electronic structures of Sc₂CF₂/Sc₂CCl₂, Sc₂CF₂/Sc₂CBr₂ [...] Read more.

Two-dimensional van der Waals heterostructures have good application prospects in solar energy conversion due to their excellent optoelectronic performance. In this work, the electronic structures of Sc₂CF₂/Sc₂CCl₂, Sc₂CF₂/Sc₂CBr₂, and Sc₂CCl₂/Sc₂CBr₂ heterostructures, as well as their properties in photocatalysis and photovoltaics, have been comprehensively studied using the first-principles method. Firstly, both of the three thermodynamically and dynamically stable heterostructures are found to have type-II band alignment with band gap values of 0.58 eV, 0.78 eV, and 1.35 eV. Meanwhile, the photogenerated carriers in Sc₂CF₂/Sc₂CCl₂ and Sc₂CF₂/Sc₂CBr₂ heterostructures are predicated to follow the direct Z-scheme path, enabling their abilities for water splitting. As for the Sc₂CCl₂/Sc₂CBr₂ heterostructure, its photovoltaic conversion efficiency is estimated to be 20.78%. Significantly, the light absorption coefficients of Sc₂CF₂/Sc₂CCl₂, Sc₂CF₂/Sc₂CBr₂, and Sc₂CCl₂/Sc₂CBr₂ heterostructures are enhanced more than those of the corresponding monolayers. Moreover, biaxial strains have been observed to considerably tune the aforementioned properties of heterostructures. All the theoretical results presented in this work demonstrate the application potential of Sc₂CX₂/Sc₂CY₂ (X, Y = F, Cl, Br) heterostructures in photocatalysis and photovoltaics. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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11 pages, 2032 KiB

Open AccessArticle

Unveiling the Low-Lying Spin States of [Fe₃S₄] Clusters via the Extended Broken-Symmetry Method

by Shibing Chu and Qiuyu Gao

Molecules 2024, 29(9), 2152; https://doi.org/10.3390/molecules29092152 - 6 May 2024

Viewed by 907

Abstract

Photosynthetic water splitting, when synergized with hydrogen production catalyzed by hydrogenases, emerges as a promising avenue for clean and renewable energy. However, theoretical calculations have faced challenges in elucidating the low-lying spin states of iron–sulfur clusters, which are integral components of hydrogenases. To [...] Read more.

Photosynthetic water splitting, when synergized with hydrogen production catalyzed by hydrogenases, emerges as a promising avenue for clean and renewable energy. However, theoretical calculations have faced challenges in elucidating the low-lying spin states of iron–sulfur clusters, which are integral components of hydrogenases. To address this challenge, we employ the Extended Broken-Symmetry method for the computation of the cubane–[Fe₃S₄] cluster within the [FeNi] hydrogenase enzyme. This approach rectifies the error caused by spin contamination, allowing us to obtain the magnetic exchange coupling constant and the energy level of the low-lying state. We find that the Extended Broken-Symmetry method provides more accurate results for differences in bond length and the magnetic coupling constant. This accuracy assists in reconstructing the low-spin ground state force and determining the geometric structure of the ground state. By utilizing the Extended Broken-Symmetry method, we further highlight the significance of the geometric arrangement of metal centers in the cluster’s properties and gain deeper insights into the magnetic properties of transition metal iron–sulfur clusters at the reaction centers of hydrogenases. This research illuminates the untapped potential of hydrogenases and their promising role in the future of photosynthesis and sustainable energy production. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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12 pages, 4558 KiB

Open AccessArticle

Construction of TiO₂/CuPc Heterojunctions for the Efficient Photocatalytic Reduction of CO₂ with Water

by Jun Wang, Shuang Fu, Peng Hou, Jun Liu, Chao Li, Hongguang Zhang and Guowei Wang

Molecules 2024, 29(8), 1899; https://doi.org/10.3390/molecules29081899 - 22 Apr 2024

Cited by 3 | Viewed by 1124

Abstract

Utilizing solar energy for photocatalytic CO₂ reduction is an attractive research field because of its convenience, safety, and practicality. The selection of an appropriate photocatalyst is the key to achieve efficient CO₂ reduction. Herein, we report the synthesis of TiO₂ [...] Read more.

Utilizing solar energy for photocatalytic CO₂ reduction is an attractive research field because of its convenience, safety, and practicality. The selection of an appropriate photocatalyst is the key to achieve efficient CO₂ reduction. Herein, we report the synthesis of TiO₂/CuPc heterojunctions by compositing CuPc with TiO₂ microspheres via a hydroxyl-induced self-assembly process. The experimental investigations demonstrated that the optimal TiO₂/0.5CuPc photocatalyst exhibited a significantly enhanced CO₂ photoreduction rate up to 32.4 μmol·g⁻¹·h⁻¹ under 300 W xenon lamp irradiation, which was 3.7 times that of the TiO₂ microspheres alone. The results of photoelectrochemical experiments indicated that the construction of the heterojunctions by introducing CuPc effectively promoted the separation and transport of photogenerated carriers, thus enhancing the catalytic effect of the photocatalyst. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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15 pages, 3245 KiB

Open AccessArticle

Pd:In-Doped TiO₂ as a Bifunctional Catalyst for the Photoelectrochemical Oxidation of Paracetamol and Simultaneous Green Hydrogen Production

by Nicolás Sacco, Alexander Iguini, Ilaria Gamba, Fernanda Albana Marchesini and Gonzalo García

Molecules 2024, 29(5), 1073; https://doi.org/10.3390/molecules29051073 - 29 Feb 2024

Cited by 1 | Viewed by 1215

Abstract

The integration of clean energy generation with wastewater treatment holds promise for addressing both environmental and energy concerns. Focusing on photocatalytic hydrogen production and wastewater treatment, this study introduces PdIn/TiO₂ catalysts for the simultaneous removal of the pharmaceutical contaminant paracetamol (PTM) and [...] Read more.

The integration of clean energy generation with wastewater treatment holds promise for addressing both environmental and energy concerns. Focusing on photocatalytic hydrogen production and wastewater treatment, this study introduces PdIn/TiO₂ catalysts for the simultaneous removal of the pharmaceutical contaminant paracetamol (PTM) and hydrogen production. Physicochemical characterization showed a high distribution of Pd and In on the support as well as a high interaction with it. The Pd and In deposition enhance the light absorption capability and significantly improve the hydrogen evolution reaction (HER) in the absence and presence of paracetamol compared to TiO₂. On the other hand, the photoelectroxidation of PTM at TiO₂ and PdIn/TiO₂ follows the full mineralization path and, accordingly, is limited by the adsorption of intermediate species on the electrode surface. Thus, PdIn-doped TiO₂ stands out as a promising photoelectrocatalyst, showcasing enhanced physicochemical properties and superior photoelectrocatalytic performance. This underscores its potential for both environmental remediation and sustainable hydrogen production. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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15 pages, 5821 KiB

Open AccessArticle

Visible Light Photoactivity of g-C₃N₄/MoS₂ Nanocomposites for Water Remediation of Hexavalent Chromium

by Chunmei Tian, Huijuan Yu, Ruiqi Zhai, Jing Zhang, Cuiping Gao, Kezhen Qi, Yingjie Zhang, Qiang Ma and Mengxue Guo

Molecules 2024, 29(3), 637; https://doi.org/10.3390/molecules29030637 - 30 Jan 2024

Viewed by 1297

Abstract

Water pollution has becoming an increasingly serious issue, and it has attracted a significant amount of attention from scholars. Here, in order remove heavy metal hexavalent chromium (Cr (VI)) from wastewater, graphitic carbon nitride (g-C₃N₄) was modified with molybdenum [...] Read more.

Water pollution has becoming an increasingly serious issue, and it has attracted a significant amount of attention from scholars. Here, in order remove heavy metal hexavalent chromium (Cr (VI)) from wastewater, graphitic carbon nitride (g-C₃N₄) was modified with molybdenum disulfide (MoS₂) at different mass ratios via an ultrasonic method to synthesize g-C₃N₄/MoS₂ (CNM) nanocomposites as photocatalysts. The nanocomposites displayed efficient photocatalytic removal of toxic hexavalent chromium (Cr (VI)) from water under UV, solar, and visible light irradiation. The CNM composite with a 1:2 g-C₃N₄ to MoS₂ ratio achieved optimal 91% Cr (VI) removal efficiency at an initial 20 mg/L Cr (VI) concentration and pH 3 after 120 min visible light irradiation. The results showed a high pH range and good recycling stability. The g-C₃N₄/MoS₂ nanocomposites exhibited higher performance compared to pure g-C₃N₄ due to the narrowed band gap of the Z-scheme heterojunction structure and effective separation of photo-generated electron–hole pairs, as evidenced by structural and optical characterization. Overall, the ultrasonic synthesis of g-C₃N₄/MoS₂ photocatalysts shows promise as an efficient technique for enhancing heavy metal wastewater remediation under solar and visible light. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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13 pages, 3204 KiB

Open AccessArticle

Rational Photodeposition of Cobalt Phosphate on Flower-like ZnIn₂S₄ for Efficient Photocatalytic Hydrogen Evolution

by Yonghui Wu, Zhipeng Wang, Yuqing Yan, Yu Wei, Jun Wang, Yunsheng Shen, Kai Yang, Bo Weng and Kangqiang Lu

Molecules 2024, 29(2), 465; https://doi.org/10.3390/molecules29020465 - 17 Jan 2024

Cited by 9 | Viewed by 1455

Abstract

The high electrons and holes recombination rate of ZnIn₂S₄ significantly limits its photocatalytic performance. Herein, a simple in situ photodeposition strategy is adopted to introduce the cocatalyst cobalt phosphate (Co-Pi) on ZnIn₂S₄, aiming at facilitating the [...] Read more.

The high electrons and holes recombination rate of ZnIn₂S₄ significantly limits its photocatalytic performance. Herein, a simple in situ photodeposition strategy is adopted to introduce the cocatalyst cobalt phosphate (Co-Pi) on ZnIn₂S₄, aiming at facilitating the separation of electron–hole by promoting the transfer of photogenerated holes of ZnIn₂S₄. The study reveals that the composite catalyst has superior photocatalytic performance than blank ZnIn₂S₄. In particular, ZnIn₂S₄ loaded with 5% Co-Pi (ZnIn₂S₄/5%Co-Pi) has the best photocatalytic activity, and the H₂ production rate reaches 3593 μmol·g⁻¹·h⁻¹, approximately double that of ZnIn₂S₄ alone. Subsequent characterization data demonstrate that the introduction of the cocatalyst Co-Pi facilitates the transfer of ZnIn₂S₄ holes, thus improving the efficiency of photogenerated carrier separation. This investigation focuses on the rational utilization of high-content and rich cocatalysts on earth to design low-cost and efficient composite catalysts to achieve sustainable photocatalytic hydrogen evolution. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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16 pages, 3011 KiB

Open AccessArticle

Visible Light Motivated the Photocatalytic Degradation of P-Nitrophenol by Ca²⁺-Doped AgInS₂

by Xuejiao Wang, Shuyuan Liu, Shu Lin, Kezhen Qi, Ya Yan and Yuhua Ma

Molecules 2024, 29(2), 361; https://doi.org/10.3390/molecules29020361 - 11 Jan 2024

Cited by 9 | Viewed by 1154 | Correction

Abstract

4-Nitrophenol (4-NP) is considered a priority organic pollutant with high toxicity. Many authors have been committed to developing efficient, green, and environmentally friendly technological processes to treat wastewater containing 4-NP. Here, we investigated how the addition of Ca²⁺ affects the catalytic degradation [...] Read more.

4-Nitrophenol (4-NP) is considered a priority organic pollutant with high toxicity. Many authors have been committed to developing efficient, green, and environmentally friendly technological processes to treat wastewater containing 4-NP. Here, we investigated how the addition of Ca²⁺ affects the catalytic degradation of 4-NP with AgInS₂ when exposed to light. We synthesized AgInS₂ (AIS) and Ca²⁺-doped AgInS₂ (Ca-AIS) with varying amounts of Ca²⁺ using a low-temperature liquid phase method. The SEM, XRD, XPS, HRTEM, BET, PL, and UV-Vis DRS characteristics were employed to analyze the structure, morphology, and optical properties of the materials. The effects of different amounts of Ca²⁺ on the photocatalytic degradation of 4-NP were investigated. Under visible light illumination for a duration of 120 min, a degradation rate of 63.2% for 4-Nitrophenol (4-NP) was achieved. The results showed that doping with an appropriate amount of Ca²⁺ could improve the visible light catalytic activity of AIS. This work provides an idea for finding suitable cheap alkaline earth metal doping agents to replace precious metals for the improvement of photocatalytic activities. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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13 pages, 4104 KiB

Open AccessArticle

Constructing In₂S₃/CdS/N-rGO Hybrid Nanosheets via One-Pot Pyrolysis for Boosting and Stabilizing Visible Light-Driven Hydrogen Evolution

by Minghao Zhang, Xiaoqun Wu, Xiaoyuan Liu, Huixin Li, Ying Wang and Debao Wang

Molecules 2023, 28(23), 7878; https://doi.org/10.3390/molecules28237878 - 30 Nov 2023

Cited by 2 | Viewed by 1122

Abstract

The construction of hybrid junctions remains challenging for the rational design of visible light-driven photocatalysts. Herein, In₂S₃/CdS/N-rGO hybrid nanosheets were successfully prepared via a one-step pyrolysis method using deep eutectic solvents as precursors. Benefiting from the surfactant-free pyrolysis method, [...] Read more.

The construction of hybrid junctions remains challenging for the rational design of visible light-driven photocatalysts. Herein, In₂S₃/CdS/N-rGO hybrid nanosheets were successfully prepared via a one-step pyrolysis method using deep eutectic solvents as precursors. Benefiting from the surfactant-free pyrolysis method, the obtained ultrathin hybrid nanosheets assemble into stable three-dimensional self-standing superstructures. The tremella-like structure of hybrid In₂S₃/N-rGO exhibits excellent photocatalytic hydrogen production performance. The hydrogen evolution rate is 10.9 mmol·g⁻¹·h⁻¹, which is greatly superior to CdS/N-rGO (3.7 mmol·g⁻¹·h⁻¹) and In₂S₃/N-rGO (2.6 mmol·g⁻¹·h⁻¹). This work provides more opportunities for the rational design and fabrication of hybrid ultrathin nanosheets for broad catalytic applications in sustainable energy and the environment. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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14 pages, 15760 KiB

Open AccessArticle

CdS Deposited In Situ on g-C₃N₄ via a Modified Chemical Bath Deposition Method to Improve Photocatalytic Hydrogen Production

by Ligang Ma, Wenjun Jiang, Chao Lin, Le Xu, Tianyu Zhu and Xiaoqian Ai

Molecules 2023, 28(23), 7846; https://doi.org/10.3390/molecules28237846 - 29 Nov 2023

Cited by 8 | Viewed by 1155

Abstract

Ultra-thin two-dimensional materials are attracting widespread interest due to their excellent properties, and they are becoming ideal candidates for a variety of energy and environmental photocatalytic applications. Herein, CdS nanorods are successfully grown in situ between a monolayer of g-C₃N₄ [...] Read more.

Ultra-thin two-dimensional materials are attracting widespread interest due to their excellent properties, and they are becoming ideal candidates for a variety of energy and environmental photocatalytic applications. Herein, CdS nanorods are successfully grown in situ between a monolayer of g-C₃N₄ using a chemical water bath method. Continuous ultrasound is introduced during the preparation process, which effectively prevents the accumulation of a g-C₃N₄ layer. The g-C₃N₄@CdS nanocomposite exhibits significantly enhanced photocatalytic activity for hydrogen production under visible-light irradiation, which is attributed to a well-matched band structure and an intimate van der Waals heterojunction interface. The mechanism of photocatalytic hydrogen production is discussed in detail. Moreover, our work can serve as a basis for the construction of other highly catalytically active two-dimensional heterostructures. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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19 pages, 3947 KiB

Open AccessArticle

The Fabrication of Halogen-Doped FeWO₄ Heterostructure Anchored over Graphene Oxide Nanosheets for the Sunlight-Driven Photocatalytic Degradation of Methylene Blue Dye

by Muhammad Irfan, Noor Tahir, Muhammad Zahid, Saima Noreen, Muhammad Yaseen, Muhammad Shahbaz, Ghulam Mustafa, Rana Abdul Shakoor and Imran Shahid

Molecules 2023, 28(20), 7022; https://doi.org/10.3390/molecules28207022 - 10 Oct 2023

Viewed by 1538

Abstract

Rapid industrialization and urbanization are the two significant issues causing environmental pollution. The polluted water from various industries contains refractory organic materials such as dyes. Heterogeneous photocatalysis using semiconductor metal oxides is an effective remediation technique for wastewater treatment. In this research, we [...] Read more.

Rapid industrialization and urbanization are the two significant issues causing environmental pollution. The polluted water from various industries contains refractory organic materials such as dyes. Heterogeneous photocatalysis using semiconductor metal oxides is an effective remediation technique for wastewater treatment. In this research, we used a co-precipitation-assisted hydrothermal method to synthesize a novel I-FeWO₄/GO sunlight-active nanocomposite. Introducing dopant reductive iodine species improved the catalytic activity of FeWO₄/GO. I⁻ ions improved the catalytic performance of H₂O₂ by doping into FeWO₄/GO composite. Due to I⁻ doping and the introduction of graphene as a support medium, enhanced charge separation and transfer were observed, which is crucial for efficient heterogeneous surface reactions. Various techniques, like FTIR, SEM-EDX, XRD, and UV–Vis spectroscopy, were used to characterize composites. The Tauc plot method was used to calculate pristine and iodine-doped FeWO₄/GO bandgap. Iodine doping reduced the bandgap from 2.8 eV to 2.6 eV. The degradation of methylene blue (MB) was evaluated by optimizing various parameters like catalyst concentration, oxidant dose, pH, and time. The optimum conditions for photocatalysts where maximum degradation occurred were pH = 7 for both FeWO₄/GO and I-FeWO₄/GO; oxidant dose = 9 mM and 7 mM for FeWO₄/GO and I-FeWO₄/GO; and catalyst concentration = 30 mg and 35 mg/100 mL for FeWO₄/GO and I-FeWO₄/GO; the optimum time was 120 min. Under these optimum conditions, FeWO₄/GO and I-FeWO₄/GO showed 92.0% and 97.0% degradation of MB dye. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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14 pages, 12085 KiB

Open AccessArticle

In Situ Decoration of Bi₂S₃ Nanosheets on Zinc Oxide/Cellulose Acetate Composite Films for Photodegradation of Dyes under Visible Light Irradiation

by Yixiao Dan, Jialiang Xu, Jian Jian, Lingxi Meng, Pei Deng, Jiaqi Yan, Zhengqiu Yuan, Yusheng Zhang and Hu Zhou

Molecules 2023, 28(19), 6882; https://doi.org/10.3390/molecules28196882 - 29 Sep 2023

Cited by 3 | Viewed by 1224

Abstract

A novel Bi₂S₃-zinc oxide/cellulose acetate composite film was prepared through a blending-wet phase conversion and in situ precipitate method. The results revealed that the incorporation of Bi₂S₃ in the film increased the cavity density and uniformity, [...] Read more.

A novel Bi₂S₃-zinc oxide/cellulose acetate composite film was prepared through a blending-wet phase conversion and in situ precipitate method. The results revealed that the incorporation of Bi₂S₃ in the film increased the cavity density and uniformity, which provided additional space for the growth of active species and improved the interaction between dye pollutants and active sites. Zinc oxide acted as a mediator to facilitate the separation of electron–hole pairs effectively preventing their recombination, thus reducing the photo-corrosion of Bi₂S₃. As a result, the Bi₂S₃-ZnO/CA composite film exhibited favorable photocatalytic activity in the degradation of various dyes. Additionally, the composite film displayed effortless separation and recovery without the need for centrifugation or filtration, while maintaining its exceptional catalytic performance even after undergoing various processes. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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21 pages, 21687 KiB

Open AccessArticle

Boosted Photocatalytic Performance for Antibiotics Removal with Ag/PW₁₂/TiO₂ Composite: Degradation Pathways and Toxicity Assessment

by Hongfei Shi, Haoshen Wang, Enji Zhang, Xiaoshu Qu, Jianping Li, Sisi Zhao, Huajing Gao and Zhe Chen

Molecules 2023, 28(19), 6831; https://doi.org/10.3390/molecules28196831 - 27 Sep 2023

Cited by 4 | Viewed by 1488

Abstract

Photocatalyst is the core of photocatalysis and directly determines photocatalytic performance. However, low quantum efficiency and low utilization of solar energy are important technical problems in the application of photocatalysis. In this work, a series of polyoxometalates (POMs) [H₃PW₁₂O [...] Read more.

Photocatalyst is the core of photocatalysis and directly determines photocatalytic performance. However, low quantum efficiency and low utilization of solar energy are important technical problems in the application of photocatalysis. In this work, a series of polyoxometalates (POMs) [H₃PW₁₂O₄₀] (PW₁₂)-doped titanium dioxide (TiO₂) nanofibers modified with various amount of silver (Ag) nanoparticles (NPs) were prepared by utilizing electrospinning/photoreduction strategy, and were labelled as x wt% Ag/PW₁₂/TiO₂ (abbr. x% Ag/PT, x = 5, 10, and 15, respectively). The as-prepared materials were characterized with a series of techniques and exhibited remarkable catalytic activities for visible-light degradation tetracycline (TC), enrofloxacin (ENR), and methyl orange (MO). Particularly, the 10% Ag/PT catalyst with a specific surface area of 155.09 m²/g and an average aperture of 4.61 nm possessed the optimal photodegradation performance, with efficiencies reaching 78.19% for TC, 93.65% for ENR, and 99.29% for MO, which were significantly higher than those of PW₁₂-free Ag/TiO₂ and PT nanofibers. Additionally, various parameters (the pH of the solution, catalyst usage, and TC concentration) influencing the degradation process were investigated in detail. The optimal conditions are as follows: catalyst usage: 20 mg; TC: 20 mL of 20 ppm; pH = 7. Furthermore, the photodegradation intermediates and pathways were demonstrated by HPLC-MS measurement. We also investigated the toxicity of products generated during TC removal by employing quantitative structure-activity relationship (QSAR) prediction through a toxicity estimation software tool (T.E.S.T. Version 5.1.2.). The mechanism study showed that the doping of PW₁₂ and the modification of Ag NPs on TiO₂ broadened the visible-light absorption, accelerating the effective separation of photogenerated carriers, therefore resulting in an enhanced photocatalytic performance. The research provided some new thoughts for exploiting efficient and durable photocatalysts for environmental remediation. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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13 pages, 4536 KiB

Open AccessArticle

Photoredox Coupling of CO₂ Reduction with Benzyl Alcohol Oxidation over Ternary Metal Chalcogenides (Zn_mIn₂S_3+m, m = 1–5) with Regulable Products Selectivity

by Zisheng Du, Kexin Gong, Zhiruo Yu, Yang Yang, Peixian Wang, Xiuzhen Zheng, Zhongliao Wang, Sujuan Zhang, Shifu Chen and Sugang Meng

Molecules 2023, 28(18), 6553; https://doi.org/10.3390/molecules28186553 - 10 Sep 2023

Cited by 4 | Viewed by 1747

Abstract

Integrating photocatalytic CO₂ reduction with selective benzyl alcohol (BA) oxidation in one photoredox reaction system is a promising way for the simultaneous utilization of photogenerated electrons and holes. Herein, Zn_mIn₂S_3+m (m = 1–5) semiconductors (ZnIn₂S [...] Read more.

Integrating photocatalytic CO₂ reduction with selective benzyl alcohol (BA) oxidation in one photoredox reaction system is a promising way for the simultaneous utilization of photogenerated electrons and holes. Herein, Zn_mIn₂S_3+m (m = 1–5) semiconductors (ZnIn₂S₄, Zn₂In₂S₅, Zn₃In₂S₆, Zn₄In₂S₇, and Zn₅In₂S₈) with various composition faults were synthesized via a simple hydrothermal method and used for effective selective dehydrocoupling of benzyl alcohol into high-value C–C coupling products and reduction of CO₂ into syngas under visible light. The absorption edge of Zn_mIn₂S_3+m samples shifted to shorter wavelengths as the atomic ratio of Zn/In was increased. The conduction band and valence band position can be adjusted by changing the Zn/In ratio, resulting in controllable photoredox ability for selective BA oxidation and CO₂ reduction. For example, the selectivity of benzaldehyde (BAD) product was reduced from 76% (ZnIn₂S₄, ZIS1) to 27% (Zn₄In₂S₇, ZIS4), while the selectivity of hydrobenzoin (HB) was increased from 22% to 56%. Additionally, the H₂ formation rate on ZIS1 (1.6 mmol/g/h) was 1.6 times higher than that of ZIS4 (1.0 mmol/g/h), and the CO formation rate on ZIS4 (0.32 mmol/g/h) was three times higher than that of ZIS1 (0.13 mmol/g/h), demonstrating that syngas with different H₂/CO ratios can be obtained by controlling the Zn/In ratio in Zn_mIn₂S_3+m. This study provides new insights into unveiling the relationship of structure–property of Zn_mIn₂S_3+m layered crystals, which are valuable for implementation in a wide range of environment and energy applications. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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14 pages, 1701 KiB

Open AccessArticle

Photoredox-Catalyzed Synthesis of 3-Sulfonylated Pyrrolin-2-ones via a Regioselective Tandem Sulfonylation Cyclization of 1,5-Dienes

by Ran Ding, Liang Li, Ya-Ting Yu, Bing Zhang and Pei-Long Wang

Molecules 2023, 28(14), 5473; https://doi.org/10.3390/molecules28145473 - 17 Jul 2023

Cited by 2 | Viewed by 1380

Abstract

A mild, visible-light-induced, regioselective cascade sulfonylation-cyclization of 1,5-dienes with sulfonyl chlorides through the intermolecular radical addition/cyclization of alkenes C(sp²)-H was developed. This procedure proceeds well and affords a mild and efficient route to a range of monosulfonylated pyrrolin-2-ones at room temperatures. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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16 pages, 3657 KiB

Open AccessArticle

Bifunctional Hot Water Vapor Template-Mediated Synthesis of Nanostructured Polymeric Carbon Nitride for Efficient Hydrogen Evolution

by Baihua Long, Hongmei He, Yang Yu, Wenwen Cai, Quan Gu, Jing Yang and Sugang Meng

Molecules 2023, 28(12), 4862; https://doi.org/10.3390/molecules28124862 - 20 Jun 2023

Cited by 4 | Viewed by 2632

Abstract

Regulating bulk polymeric carbon nitride (PCN) into nanostructured PCN has long been proven effective in enhancing its photocatalytic activity. However, simplifying the synthesis of nanostructured PCN remains a considerable challenge and has drawn widespread attention. This work reported the one-step green and sustainable [...] Read more.

Regulating bulk polymeric carbon nitride (PCN) into nanostructured PCN has long been proven effective in enhancing its photocatalytic activity. However, simplifying the synthesis of nanostructured PCN remains a considerable challenge and has drawn widespread attention. This work reported the one-step green and sustainable synthesis of nanostructured PCN in the direct thermal polymerization of the guanidine thiocyanate precursor via the judicious introduction of hot water vapor’s dual function as gas-bubble templates along with a green etching reagent. By optimizing the temperature of the water vapor and polymerization reaction time, the as-prepared nanostructured PCN exhibited a highly boosted visible-light-driven photocatalytic hydrogen evolution activity. The highest H₂ evolution rate achieved was 4.81mmol∙g⁻¹∙h⁻¹, which is over four times larger than that of the bulk PCN (1.19 mmol∙g⁻¹∙h⁻¹) prepared only by thermal polymerization of the guanidine thiocyanate precursor without the assistance of bifunctional hot water vapor. The enhanced photocatalytic activity might be attributed to the enlarged BET specific surface area, increased active site quantity, and highly accelerated photo-excited charge-carrier transfer and separation. Moreover, the sustainability of this environmentally friendly hot water vapor dual-function mediated method was also shown to be versatile in preparing other nanostructured PCN photocatalysts derived from other precursors such as dicyandiamide and melamine. This work is expected to provide a novel pathway for exploring the rational design of nanostructured PCN for highly efficient solar energy conversion. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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16 pages, 9484 KiB

Open AccessArticle

Synthesis and Hydrogen Production Performance of MoP/a-TiO₂/Co-ZnIn₂S₄ Flower-like Composite Photocatalysts

by Keliang Wu, Yuhang Shang, Huazhen Li, Pengcheng Wu, Shuyi Li, Hongyong Ye, Fanqiang Jian, Junfang Zhu, Dongmei Yang, Bingke Li and Xiaofei Wang

Molecules 2023, 28(11), 4350; https://doi.org/10.3390/molecules28114350 - 25 May 2023

Cited by 9 | Viewed by 1729

Abstract

Semiconductor photocatalysis is an effective strategy for solving the problems of increasing energy demand and environmental pollution. ZnIn₂S₄-based semiconductor photocatalyst materials have attracted much attention in the field of photocatalysis due to their suitable energy band structure, stable chemical [...] Read more.

Semiconductor photocatalysis is an effective strategy for solving the problems of increasing energy demand and environmental pollution. ZnIn₂S₄-based semiconductor photocatalyst materials have attracted much attention in the field of photocatalysis due to their suitable energy band structure, stable chemical properties, and good visible light responsiveness. In this study, ZnIn₂S₄ catalysts were modified by metal ion doping, the construction of heterojunctions, and co-catalyst loading to successfully prepare composite photocatalysts. The Co-ZnIn₂S₄ catalyst synthesized by Co doping and ultrasonic exfoliation exhibited a broader absorption band edge. Next, an a-TiO₂/Co-ZnIn₂S₄ composite photocatalyst was successfully prepared by coating partly amorphous TiO₂ on the surface of Co-ZnIn₂S₄, and the effect of varying the TiO₂ loading time on photocatalytic performance was investigated. Finally, MoP was loaded as a co-catalyst to increase the hydrogen production efficiency and reaction activity of the catalyst. The absorption edge of MoP/a-TiO₂/Co-ZnIn₂S₄ was widened from 480 nm to about 518 nm, and the specific surface area increased from 41.29 m²/g to 53.25 m²/g. The hydrogen production performance of this composite catalyst was investigated using a simulated light photocatalytic hydrogen production test system, and the rate of hydrogen production by MoP/a-TiO₂/Co-ZnIn₂S₄ was found to be 2.96 mmol·h⁻¹·g⁻¹, which was three times that of the pure ZnIn₂S₄ (0.98 mmol·h⁻¹·g⁻¹). After use in three cycles, the hydrogen production only decreased by 5%, indicating that it has good cycle stability. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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17 pages, 5166 KiB

Open AccessArticle

One-Step Synthesis of Ag₂O/Fe₃O₄ Magnetic Photocatalyst for Efficient Organic Pollutant Removal via Wide-Spectral-Response Photocatalysis–Fenton Coupling

by Chuanfu Shan, Ziqian Su, Ziyi Liu, Ruizheng Xu, Jianfeng Wen, Guanghui Hu, Tao Tang, Zhijie Fang, Li Jiang and Ming Li

Molecules 2023, 28(10), 4155; https://doi.org/10.3390/molecules28104155 - 17 May 2023

Cited by 6 | Viewed by 2073

Abstract

Photocatalysis holds great promise for addressing water pollution caused by organic dyes, and the development of Ag₂O/Fe₃O₄ aims to overcome the challenges of slow degradation efficiency and difficult recovery of photocatalysts. In this study, we present a novel, [...] Read more.

Photocatalysis holds great promise for addressing water pollution caused by organic dyes, and the development of Ag₂O/Fe₃O₄ aims to overcome the challenges of slow degradation efficiency and difficult recovery of photocatalysts. In this study, we present a novel, environmentally friendly Ag₂O/Fe₃O₄ magnetic nanocomposite synthesized via a simple coprecipitation method, which not only constructs a type II heterojunction but also successfully couples photocatalysis and Fenton reaction, enhancing the broad-spectrum response and efficiency. The Ag₂O/Fe₃O₄ (10%) nanocomposite demonstrates exceptional degradation performance toward organic dyes, achieving 99.5% degradation of 10 mg/L methyl orange (MO) within 15 min under visible light irradiation and proving its wide applicability by efficiently degrading various dyes while maintaining high stability over multiple testing cycles. Magnetic testing further highlighted the ease of Ag₂O/Fe₃O₄ (10%) recovery using magnetic force. This innovative approach offers a promising strategy for constructing high-performance photocatalytic systems for addressing water pollution caused by organic dyes. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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1 pages, 131 KiB

Open AccessCorrection

Correction: Wang et al. Visible Light Motivated the Photocatalytic Degradation of P-Nitrophenol by Ca²⁺-Doped AgInS₂. Molecules 2024, 29, 361

by Xuejiao Wang, Shuyuan Liu, Shu Lin, Kezhen Qi, Ya Yan and Yuhua Ma

Molecules 2024, 29(12), 2764; https://doi.org/10.3390/molecules29122764 - 11 Jun 2024

Viewed by 470

Abstract

In the original publication [...] Full article

(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)

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