Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy

Topic Information

Dear Colleagues,

As the most important fossil fuel, petroleum is supplied worldwide to satisfy the major demands of industries, transportation, and civil activities.  As low-sulfur sweet crude oil reservoirs have been depleted, petroleum that contains more and heavier sulfur compounds has become the main refinery feedstock. These crude oils usually contain a spectrum of organosulfur compounds which must be removed before feeding catalytic cracking refining facilities in order to avoid the excessive release of air pollutants and the rapid deactivation of the catalyst. As increasingly strict environmental regulations are taking effect worldwide, sulfur content in oil products such as diesel and gasoline has been limited to lower than 10 ppm, and thus, ultralow-sulfur fuels produced using deep desulfurization techniques are in high demand.

On the other hand, scientists and researchers from the academic and industrial sectors are investigating other renewable and clean energy sources such as biofuels, hydrogen, and solar energy.  In the traditional and new fuel production processes, catalysis always plays a central role in the improvement of the reactant conversion for product selectivity and energy efficiency.

This Topic entitled “Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy” highlights the state of the art of nanomaterials and nanocatalysts and their applications in the production of clean fuels and sustainable energy. New findings in fundamental research, including novel synthesis routes, advanced characterization, together with applications for petroleum refining processes, ultralow-sulfur fuel production, biofuel production, hydrogen production, and solar energy conversion and storage are of prime importance to this Topic. 

This Topic covers but is not limited to the following topics:

• Oxidative desulfurization;
• Hydrodesulfuration;
• Hydroisomerization and alkylation;
• Catalysts for Fischer–Tropsch synthesis;
• CO₂ mitigation and photoconversion to alcohols.

• Acidic catalysts for biofuel production;
• Base catalysts for biofuel production;
• Biocatalysts for biofuel production;

• Photocatalysis for water splitting;
• Electrocatalysis for H₂ production;
• The catalytic decomposition of natural gases for hydrogen and carbon nanotube production;
• Catalysis for alcohol reforming processes (methanol, ethanol and glycerol…).

• The synthesis and applications of core–shell photocatalysts;
• Solar energy conversion, storage, and applications.

Research papers and review or mini review papers related these topics will be particularly welcome. We are also planning to publish some selected articles contributing to this Topic in a book.

Prof. Dr. Jin An Wang
Prof. Dr. Lifang Chen
Prof. Dr. Luis Enrique Noreña
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Applied Sciences applsci	2.5	5.3	2011	17.8 Days	CHF 2400
Catalysts catalysts	3.8	6.8	2011	12.9 Days	CHF 2200
Clean Technologies cleantechnol	4.0	6.1	2019	30 Days	CHF 1600
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600
Nanomaterials nanomaterials	4.4	8.5	2010	13.8 Days	CHF 2900

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Published Papers (12 papers)

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All Applied Sciences Catalysts Clean Technol. Energies Nanomaterials

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19 pages, 2014 KiB  

Open AccessArticle

A Cluster-Type Self-Healing Catalyst for Stable Saline–Alkali Water Splitting

by Haiming Wang and Sheng Chen

Catalysts 2024, 14(1), 81; https://doi.org/10.3390/catal14010081 - 18 Jan 2024

Cited by 2 | Viewed by 1407

Abstract

In electrocatalytic processes, traditional powder/film electrodes inevitably suffer from damage or deactivation, reducing their catalytic performance and stability. In contrast, self-healing electrocatalysts, through special structural design or composition methods, can automatically repair at the damaged sites, restoring their electrocatalytic activity. Here, guided by [...] Read more.

In electrocatalytic processes, traditional powder/film electrodes inevitably suffer from damage or deactivation, reducing their catalytic performance and stability. In contrast, self-healing electrocatalysts, through special structural design or composition methods, can automatically repair at the damaged sites, restoring their electrocatalytic activity. Here, guided by Pourbaix diagrams, foam metal was activated by a simple cyclic voltammetry method to synthesize metal clusters dispersion solution (MC/KOH). The metal clusters-modified hydroxylated Ni-Fe oxyhydroxide electrode (MC/Ni_xFe_yOOH) by a facile Ni-Fe metal–organic framework-reconstructed strategy, exhibiting superior performance toward the oxygen evolution reaction (OER) in the mixture of MC/KOH and saline–alkali water (MC/KOH+SAW). Specifically, using a nickel clusters-modified hydroxylated Ni-Fe oxyhydroxide electrode (NC/Ni_xFe_yOOH) for OER, the NC/Ni_xFe_yOOH catalyst has an ultra-low overpotential of 149 mV@10 mA cm⁻², and durable stability of 100 h at 500 mA cm⁻². By coupling this OER catalyst with an efficient hydrogen evolution reaction catalyst, high activity and durability in overall SAW splitting is exhibited. What is more, benefiting from the excellent fluidity, flexibility, and enhanced catalytic activity effect of the liquid NC, we demonstrate a self-healing electrocatalysis system for OER operated in the flowing NC/(KOH+SAW). This strategy provides innovative solutions for the fields of sustainable energy and environmental protection. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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12 pages, 4409 KiB  

Open AccessArticle

Facile Synthesis of Ni³⁺/Co³⁺ Ion-Doped Zn₂SnO₄ Microspheres toward Efficient Photocatalytic CO₂ Reduction

by Yanlong Yu, Jun Zhang, Yi Lin, Dandan Zhao, Ziying Li and Sai Yan

Appl. Sci. 2023, 13(24), 13193; https://doi.org/10.3390/app132413193 - 12 Dec 2023

Cited by 1 | Viewed by 1169

Abstract

The photocatalytic reduction of CO₂ into hydrocarbons is a promising solution for the energy crisis and greenhouse gas emissions. Thus, the fabrication and development of a new type of photocatalyst is of great importance for the practical application of CO₂ reduction. [...] Read more.

The photocatalytic reduction of CO₂ into hydrocarbons is a promising solution for the energy crisis and greenhouse gas emissions. Thus, the fabrication and development of a new type of photocatalyst is of great importance for the practical application of CO₂ reduction. Herein, we report a facile synthesis of Zn₂SnO₄ (ZTO) microspheres doped with Co³⁺ ions or Ni³⁺ ions. The doped Co³⁺/Ni³⁺ ions substitute the lattice Zn/Sn ions. DFT calculations and experimental results reveal that the doped Co³⁺/Ni³⁺ ions would induce new doping energy levels in the band gap, extend the light response from the UV to the visible region, and separate the charge carriers. As a result, compared with pure ZTO, the photocatalytic activity of a CO₂ reduction into CH₄ is significantly improved for Co-doped ZTO (Co-ZTO) and Ni-doped ZTO (Ni-ZTO). Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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13 pages, 7504 KiB  

Open AccessArticle

Construction of Hollow Co₃O₄@ZnIn₂S₄ p-n Heterojunctions for Highly Efficient Photocatalytic Hydrogen Production

by Zijian Xin, Haizhao Zheng and Juncheng Hu

Nanomaterials 2023, 13(4), 758; https://doi.org/10.3390/nano13040758 - 17 Feb 2023

Cited by 4 | Viewed by 2320

Abstract

Photocatalysts derived from semiconductor heterojunctions for water splitting have bright prospects in solar energy conversion. Here, a Co₃O₄@ZIS p-n heterojunction was successfully created by developing two-dimensional ZnIn₂S₄ on ZIF-67-derived hollow Co₃O₄ nanocages, realizing [...] Read more.

Photocatalysts derived from semiconductor heterojunctions for water splitting have bright prospects in solar energy conversion. Here, a Co₃O₄@ZIS p-n heterojunction was successfully created by developing two-dimensional ZnIn₂S₄ on ZIF-67-derived hollow Co₃O₄ nanocages, realizing efficient spatial separation of the electron-hole pair. Moreover, the black hollow structure of Co₃O₄ considerably increases the range of light absorption and the light utilization efficiency of the heterojunction avoids the agglomeration of ZnIn₂S₄ nanosheets and further improves the hydrogen generation rate of the material. The obtained Co₃O₄(20) @ZIS showed excellent photocatalytic H₂ activity of 5.38 mmol g⁻¹·h⁻¹ under simulated solar light, which was seven times more than that of pure ZnIn₂S₄. Therefore, these kinds of constructions of hollow p-n heterojunctions have a positive prospect in solar energy conversion fields. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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18 pages, 3236 KiB  

Open AccessArticle

Microencapsulation of Lipases Produced by Dripping and Jet Break-Up for Biodiesel Production

by Boris Guzmán-Martínez, Roberto Limas-Ballesteros, Jin An Wang, Liliana Alamilla-Beltrán, Lifang Chen and Luis Enrique Noreña

Energies 2022, 15(24), 9411; https://doi.org/10.3390/en15249411 - 12 Dec 2022

Cited by 1 | Viewed by 1572

Abstract

A high-performance and scalable lipase immobilization method using a dipping and jet break-up technique was reported for the production of microcapsule biocatalysts with an entrapped cascade of lipase enzyme. The lipase from Candida antarctica (CALb) recombinant Aspergillus oryzae and from the vegetal of [...] Read more.

A high-performance and scalable lipase immobilization method using a dipping and jet break-up technique was reported for the production of microcapsule biocatalysts with an entrapped cascade of lipase enzyme. The lipase from Candida antarctica (CALb) recombinant Aspergillus oryzae and from the vegetal of Jatropha curcas L. (var. Sevangel) in Morelos State of Mexico were entrapped by mixing with a sodium alginate biopolymer at different concentrations. The obtained microcapsules were hardened in a CaCl₂ solution, aiming at developing Ca²⁺ alginate microbeads with sizes mostly from 220 to 300 μm. The relationship between the process variables with the shape and size of the alginate drops before and after the gelation was established with aid of optical image analysis. The results showed that a critical Ohnesorge number (Oh) > 0.24 was required to form spherical microencapsulated beads. The biodiesel production via esterification/transesterification reaction was performed using the crude Jatropha curcas L. oil as feedstock in a batch reactor using lipase microcapsules as biocatalysts. Under the optimal reaction condition (ethanol-to-oil mass ratio: 10; water content 9.1 wt%, microencapsulated biocatalyst mass: 5.25 g, reaction temperature: 35 °C, pH of reaction mixture 7.5, stirring force 6 g), an approximately 95% fatty acid ethyl esters (FAEE) yield could be obtained. The biodiesel obtained from this work completely satisfied with the related ASTM D6751 and EN14214 standards. The microencapsulation technique reported herein allows the production of lipase microcapsules on a continuous large scale with the characteristics required for sustainable biofuel production and it can be also applied in other fields such as food processing and the pharmaceutical industry. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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33 pages, 16524 KiB  

Open AccessReview

A Review on the Progress and Future of TiO₂/Graphene Photocatalysts

by Amara Nasir, Sadia Khalid, Tariq Yasin and Anca Mazare

Energies 2022, 15(17), 6248; https://doi.org/10.3390/en15176248 - 27 Aug 2022

Cited by 31 | Viewed by 4442

Abstract

TiO₂ is seen as a low cost, well-known photocatalyst; nevertheless, its sluggish charge kinetics does limit its applications. To overcome this aspect, one of the recent approaches is the use of its composites with graphene to enhance its photoactivity. Graphene-based materials (nanosheets, [...] Read more.

TiO₂ is seen as a low cost, well-known photocatalyst; nevertheless, its sluggish charge kinetics does limit its applications. To overcome this aspect, one of the recent approaches is the use of its composites with graphene to enhance its photoactivity. Graphene-based materials (nanosheets, quantum dots, etc.) allow for attachment with TiO₂ nanostructures, resulting in synergistic properties and thus increasing the functionality of the resulting composite. The current review aims to present the marked progress recently achieved in the use of TiO₂/graphene composites in the field of photocatalysis. In this respect, we highlight the progress and insights in TiO₂ and graphene composites in photocatalysis, including the basic mechanism of photocatalysis, the possible design strategies of the composites and an overview of how to characterize the graphene in the mixed composites. The use of composites in photocatalysis has also been reviewed, in which the recent literature has opened up more questions related to the reliability, potential, repeatability and connection of photocatalytic mechanisms with the resulting composites. TiO₂/graphene-based composites can be a green light in the future of photocatalysis, targeting pollution remediation, energy generation, etc. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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15 pages, 7015 KiB  

Open AccessArticle

Sodium Pre-Intercalation-Based Na₃-δ-MnO₂@CC for High-Performance Aqueous Asymmetric Supercapacitor: Joint Experimental and DFT Study

by Anis Ur Rahman, Nighat Zarshad, Wu Jianghua, Muslim Shah, Sana Ullah, Guigen Li, Muhammad Tariq and Asad Ali

Nanomaterials 2022, 12(16), 2856; https://doi.org/10.3390/nano12162856 - 18 Aug 2022

Cited by 7 | Viewed by 2540

Abstract

Electrochemical energy storage devices are ubiquitous for personal electronics, electric vehicles, smart grids, and future clean energy demand. SCs are EES devices with excellent power density and superior cycling ability. Herein, we focused on the fabrication and DFT calculations of Na₃-δ-MnO [...] Read more.

Electrochemical energy storage devices are ubiquitous for personal electronics, electric vehicles, smart grids, and future clean energy demand. SCs are EES devices with excellent power density and superior cycling ability. Herein, we focused on the fabrication and DFT calculations of Na₃-δ-MnO₂ nanocomposite, which has layered MnO₂ redox-active sites, supported on carbon cloth. MnO₂ has two-dimensional diffusion channels and is not labile to structural changes during intercalation; therefore, it is considered the best substrate for intercalation. Cation pre-intercalation has proven to be an effective way of increasing inter-layered spacing, optimizing the crystal structure, and improving the relevant electrochemical behavior of asymmetric aqueous supercapacitors. We successfully established Na⁺ pre-intercalated δ-MnO₂ nanosheets on carbon cloth via one-pot hydrothermal synthesis. As a cathode, our prepared material exhibited an extended potential window of 0–1.4 V with a remarkable specific capacitance of 546 F g⁻¹(300 F g⁻¹ at 50 A g⁻¹). Moreover, when this cathode was accompanied by an N-AC anode in an asymmetric aqueous supercapacitor, it illustrated exceptional performance (64 Wh kg⁻¹ at a power density of 1225 W kg⁻¹) and incomparable potential window of 2.4 V and 83% capacitance retention over 10,000 cycles with a great Columbic efficiency. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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22 pages, 7084 KiB  

Open AccessArticle

Bifunctional Co₃O₄/ZSM-5 Mesoporous Catalysts for Biodiesel Production via Esterification of Unsaturated Omega-9 Oleic Acid

by Francisco Núñez, Lifang Chen, Jin An Wang, Sergio Ordin Flores, José Salmones, Ulises Arellano, Luis Enrique Noreña and Francisco Tzompantzi

Catalysts 2022, 12(8), 900; https://doi.org/10.3390/catal12080900 - 16 Aug 2022

Cited by 15 | Viewed by 2232

Abstract

In the present work, two sets of the Co/ZSM-5 mesoporous catalysts with different acidity and Co loadings varying from 1 to 5 and 10 wt% were prepared using mesoporous ZSM-5-A (Si/Al = 50) and ZSM-5-B (Si/Al = 150) as support. X-ray diffraction (XRD) [...] Read more.

In the present work, two sets of the Co/ZSM-5 mesoporous catalysts with different acidity and Co loadings varying from 1 to 5 and 10 wt% were prepared using mesoporous ZSM-5-A (Si/Al = 50) and ZSM-5-B (Si/Al = 150) as support. X-ray diffraction (XRD) analysis showed that the Co₃O₄ phase was formed in the surface of catalysts and the reducibility of Co₃O₄ nanoparticles on the ZSM-5-B was greater in comparison with that on the ZSM-5-A solid. In situ FTIR of pyridine adsorption characterization confirmed that all of the Co/ZSM-5 catalysts contained both Lewis (L) and Brønsted (B) acid sites, with a relatively balanced B/L ratio ranging from 0.61 to 1.94. Therefore, the Si/Al molar ratio in ZSM-5 affected both the surface acidity and the cobalt oxide reducibility. In the esterification of unsaturated omega-9 oleic acid with methanol, under the optimal reaction conditions (temperature 160 °C, catalyst concentration 2 g/L, methanol/oleic acid molar ratio 30, and reaction time 180 min), the biodiesel selectivity reached 95.1% over the most active 10 wt% Co/ZSM-5-B catalyst. The higher esterification activity of the Co/ZSM-5-B catalysts can be correlated with the greater amount of B and L acid sites, the balanced B/L ratio, and the higher reducibility of Co₃O₄ nanoparticles. The oleic acid esterification reaction followed the bifunctional mechanism of combining metal function (dispersed Co₃O₄ with a greater reducibility) with the acidity function (both B and L acid sites with a relative balanced B/L ratio) on the catalysts, which may help in providing a deep understanding of the esterification pathways and benefiting the design of novel bifunctional catalysts for biofuel production. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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Supplementary File 1 (ZIP, 381 KiB)

10 pages, 2024 KiB  

Open AccessArticle

Improving Photoelectrochemical Activity of Magnetron-Sputtered Double-Layer Tungsten Trioxide Photoanodes by Irradiation with Intense Pulsed Ion Beams

by Alshyn Abduvalov, Marat Kaikanov, Timur Sh. Atabaev and Alexander Tikhonov

Nanomaterials 2022, 12(15), 2639; https://doi.org/10.3390/nano12152639 - 31 Jul 2022

Cited by 3 | Viewed by 1916

Abstract

The photoelectrochemical (PEC) activity of metal oxide photoelectrodes for water-splitting applications can be boosted in several different ways. In this study, we showed that PEC activity can be significantly improved with a double-layer (crystalline-amorphous) configuration of WO₃ thin films irradiated with intense [...] Read more.

The photoelectrochemical (PEC) activity of metal oxide photoelectrodes for water-splitting applications can be boosted in several different ways. In this study, we showed that PEC activity can be significantly improved with a double-layer (crystalline-amorphous) configuration of WO₃ thin films irradiated with intense pulsed ion beams (IPIB) of a nanosecond duration. It was found that IPIB irradiation promotes the formation of crystalline and sponge-like WO₃ structures on the surface. Due to an increase in the active surface and light scattering in irradiated samples, photocurrent generation increased by ~80% at 1.23 reversible hydrogen electrodes (RHE). Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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11 pages, 4318 KiB  

Open AccessArticle

Nanoporous Silicon with Graphene-like Coating for Pseudocapacitor Application

by Daria M. Sedlovets, Anton P. Naumov, Victor I. Korotitsky and Vitaly V. Starkov

Nanomaterials 2022, 12(13), 2191; https://doi.org/10.3390/nano12132191 - 26 Jun 2022

Cited by 2 | Viewed by 1857

Abstract

This paper presents the results of studies of the nanoporous silicon structure, both with different pore depths (up to 180 μm) and with layers in which a graphene-like coating was synthesized on the inner surface of the pores. The nanoporous layers were characterized [...] Read more.

This paper presents the results of studies of the nanoporous silicon structure, both with different pore depths (up to 180 μm) and with layers in which a graphene-like coating was synthesized on the inner surface of the pores. The nanoporous layers were characterized by SEM as well as IR and Raman spectroscopy. Cyclic voltammetry and galvanostatic charge–discharge data in 3 M H₂SO₄ are presented as well as the results of the cyclic stability of these characteristics for the nanoporous structure. It was found that the degree of electrolyte pre-impregnation significantly affected the electrochemical processes, and the capacitance values depended on the depth (thickness) of the nanoporous layer. Increasing the thickness of the porous layer led to an increase in area-normalized pseudocapacity and was limited only by the mechanical strength of the structure. Performance improvement was also achieved by synthesis of the graphene-like layer in the volume of the nanoporous structure. The electrodes (composite materials) proposed in the work showed one of the best capacitive characteristics (87 mF/cm² with 100% capacity retention after 15,000 cycles) in comparison with the data reported in the literature at present. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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20 pages, 3856 KiB  

Open AccessArticle

Cr/13X Zeolite and Zn/13X Zeolite Nanocatalysts Used in Pyrolysis of Pretreated Residual Biomass to Produce Bio-Oil with Improved Quality

by Elena David and Adrian Armeanu

Nanomaterials 2022, 12(12), 1960; https://doi.org/10.3390/nano12121960 - 8 Jun 2022

Cited by 1 | Viewed by 2078

Abstract

By loading Cr and Zn on 13X zeolite, efficient nanocatalysts were prepared; they were characterized by different techniques and used for corn cobs pyrolysis to produce bio-oil. The corn cobs biomass (CCB) was washed with sulfuric acid 0.1 M, and the characteristics of [...] Read more.

By loading Cr and Zn on 13X zeolite, efficient nanocatalysts were prepared; they were characterized by different techniques and used for corn cobs pyrolysis to produce bio-oil. The corn cobs biomass (CCB) was washed with sulfuric acid 0.1 M, and the characteristics of the pretreated biomass (PTCCB) were analyzed. Pyrolysis was performed at different catalyst-to-biomass ratios (C/B), and the composition of the obtained bio-oil was determined. The results showed that the crystallinity of the nanocatalysts was slightly lower than that of the pattern 13X zeolite. The surface observation of the nanocatalysts showed the presence of pores and particles, which are quite evenly dispersed on the surface, and no difference was observed in the morphology of the Zn/13X zeolite and Cr /13X zeolite nanocatalysts. In comparison to 13X zeolite, the morphological changes, metal dispersion, and surface area decrease of both Zn/13X and Cr/13X zeolite nanocatalysts could be observed. Pyrolysis tests demonstrated that the use of Zn/13X zeolite and Cr/13X zeolite nanocatalysts could be very profitable to obtain a high conversion to hydrocarbons of the compounds containing oxygen, and consequently, the quality of the bio-oil was improved. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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14 pages, 6697 KiB  

Open AccessFeature PaperArticle

Photoelectrochemical Enhancement of Graphene@WS₂ Nanosheets for Water Splitting Reaction

by Mahmoud Nasr, Lamyae Benhamou, Ahmed Kotbi, Nitul S. Rajput, Andrea Campos, Abdel-Ilah Lahmar, Khalid Hoummada, Khaled Kaja, Mimoun El Marssi and Mustapha Jouiad

Nanomaterials 2022, 12(11), 1914; https://doi.org/10.3390/nano12111914 - 3 Jun 2022

Cited by 12 | Viewed by 2801

Abstract

Tungsten disulfide nanosheets were successfully prepared by one-step chemical vapor deposition using tungsten oxide and thiourea in an inert gas environment. The size of the obtained nanosheets was subsequently reduced down to below 20 nm in width and 150 nm in length using [...] Read more.

Tungsten disulfide nanosheets were successfully prepared by one-step chemical vapor deposition using tungsten oxide and thiourea in an inert gas environment. The size of the obtained nanosheets was subsequently reduced down to below 20 nm in width and 150 nm in length using high-energy ball milling, followed by 0.5 and 1 wt% graphene loading. The corresponding vibrational and structural characterizations are consistent with the fabrication of a pure WS₂ structure for neat sampling and the presence of the graphene characteristic vibration modes in graphene@WS₂ compounds. Additional morphological and crystal structures were examined and confirmed by high-resolution electron microscopy. Subsequently, the investigations of the optical properties evidenced the high optical absorption (98%) and lower band gap (1.75 eV) for the graphene@WS₂ compared to the other samples, with good band-edge alignment to water-splitting reaction. In addition, the photoelectrochemical measurements revealed that the graphene@WS₂ (1 wt%) exhibits an excellent photocurrent density (95 μA/cm² at 1.23 V bias) compared with RHE and higher applied bias potential efficiency under standard simulated solar illumination AM1.5G. Precisely, graphene@WS₂ (1 wt%) exhibits 3.3 times higher performance compared to pristine WS₂ and higher charge transfer ability, as measured by electrical impedance spectroscopy, suggesting its potential use as an efficient photoanode for hydrogen evolution reaction. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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12 pages, 2991 KiB  

Open AccessArticle

Enhanced Photocatalytic Activity of Nonuniformly Nitrogen-Doped Nb₂O₅ by Prolonging the Lifetime of Photogenerated Holes

by Wei Guo, Chang Bo, Wenjing Li, Zhiying Feng, Erli Cong, Lijuan Yang and Libin Yang

Nanomaterials 2022, 12(10), 1690; https://doi.org/10.3390/nano12101690 - 16 May 2022

Cited by 5 | Viewed by 2047

Abstract

The narrow band gap and significant separation of photogenerated carriers are essential aspects in practical photocatalytic applications. Nitrogen doping usually narrows the band gap of semiconductor oxides, and it enhances photocatalytic activity. Nitrogen-doped Nb₂O₅ was prepared by a multiple hydrothermal [...] Read more.

The narrow band gap and significant separation of photogenerated carriers are essential aspects in practical photocatalytic applications. Nitrogen doping usually narrows the band gap of semiconductor oxides, and it enhances photocatalytic activity. Nitrogen-doped Nb₂O₅ was prepared by a multiple hydrothermal method. The non-metal element N inside the nanostructure, working as the trapping sites for the holes, which were effectively incorporated into the crystal lattice of Nb₂O₅ semiconductor oxide, remarkably shorten the band gap (3.1 eV) to enhance the visible light response, effectively reducing the photoinduced electron–hole pair recombination and prolonging carrier lifetime. The multilayer coating structure with a gradient concentration distribution and the type of nitrogen doped is favorable for the migration of photoexcited carriers in the bulk of catalysts. The unique multi-layer coating with the micro-concentration gradient of doped nitrogen provides a fast separation channel and jump steps for the separation of electron–hole pairs. Full article

(This article belongs to the Topic Nanomaterials and Catalysts for Clean Fuels and Sustainable Energy)

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