Nanocatalyst for Water Splitting

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 10267

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State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
Interests: materials for energy and environment; photocatalysis and electrocatalysis; semiconductor materials and devices
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the increasing energy consumption and environmental contamination, it is imperative to develop sustainable, fossil-free pathways to produce fuels and chemicals of global importance. Catalytic water splitting provides a promising way to covert the highly abundant resource­­ water into quite an ideal clean energy, i.e., hydrogen, via photo-/electrochemical processes. Nanocatalysts play a decisive role in these catalytic processes, and thus the design and development of efficient nanocatalysts for water splitting have attracted considerable attention in the past several decades. In this context, much effort has been devoted to improving the water-splitting performance of nanocatalysts including: i) increasing the number of active sites and/or increasing the intrinsic activity of each active site for electrocatalysts, and ii) extending the spectral range of visible light absorption, enhancing photo-generated charge separation and transport, and facilitating the hydrogen and/or oxygen evolution reactions as for photocatalysts. However, state-of-the-art nanocatalysts for water splitting are yet inadequate. The development of advanced nanocatalysts for photo-/electrocatalytic water splitting with sufficient performance remains a grand challenge.

The present Special Issue of Nanomaterials is aimed at collecting and reporting research concerning nanocatalysts for photo- and electrocatalytic water splitting, involving inspirational synthesis methods, innovative modification strategies, outstanding catalytic performance, and comprehensive mechanism investigation. We invite authors to contribute original research articles, communications, and review articles for peer-reviewed publication covering the most recent progress and development in the area of nanomaterials for catalytic water splitting.

Prof. Dr. Peng Wang
Guest Editor

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Keywords

  • water splitting
  • photocatalytic
  • electrocatalytic
  • nanocatalysts
  • green hydrogen production

Published Papers (6 papers)

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Research

17 pages, 8592 KiB  
Article
Highly Efficient Spatial Three-Level CoP@ZIF-8/pNF Based on Modified Porous NF as Dual Functional Electrocatalyst for Water Splitting
by Hongzhi Wang, Limin Zhang, Weiguo Zhang, Shaofeng Sun and Suwei Yao
Nanomaterials 2023, 13(8), 1386; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13081386 - 17 Apr 2023
Cited by 2 | Viewed by 1618
Abstract
The development of non-noble metal catalysts for water electrolysis to product hydrogen meets the current strategic need for carbon peaking and carbon neutrality. However, complex preparation methods, low catalytic activity and high energy consumption still limit the application of these materials. Herein, in [...] Read more.
The development of non-noble metal catalysts for water electrolysis to product hydrogen meets the current strategic need for carbon peaking and carbon neutrality. However, complex preparation methods, low catalytic activity and high energy consumption still limit the application of these materials. Herein, in this work we prepared a three-level structured electrocatalyst of CoP@ZIF-8 growing on modified porous nickel foam (pNF) via the natural growing and phosphating process. In contrast to the common NF, the modified NF constructs a large number of micron-sized pores carrying the nanoscaled catalytic CoP@ZIF-8 on the millimeter-sized skeleton of bare NF, which significantly increases the specific surface area and catalyst load of the material. Thanks to the unique spatial three-level porous structure, electrochemical tests showed a low overpotential of 77 mV at 10 mA cm−2 for HER, and 226 mV at 10 mA cm−2 and 331 mV at 50 mA cm−2 for OER. The result obtained from testing the electrode’s overall water splitting performance is also satisfactory, needing only 1.57 V at 10 mA cm−2. Additionally, this electrocatalyst showed great stability for more than 55 h when a 10 mA cm−2 constant current was applied to it. Based on the above characteristics, the present work demonstrates the promising application of this material to the electrolysis of water for the production of hydrogen and oxygen. Full article
(This article belongs to the Special Issue Nanocatalyst for Water Splitting)
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16 pages, 5410 KiB  
Article
Mn3O4@ZnO Hybrid Material: An Excellent Photocatalyst for the Degradation of Synthetic Dyes including Methylene Blue, Methyl Orange and Malachite Green
by Benazir Shaikh, Muhammad Ali Bhatti, Aqeel Ahmed Shah, Aneela Tahira, Abdul Karim Shah, Azam Usto, Umair Aftab, Sarah I. Bukhari, Sultan Alshehri, Syed Nizam Uddin Shah Bukhari, Matteo Tonezzer, Brigitte Vigolo and Zaffar Hussain Ibhupoto
Nanomaterials 2022, 12(21), 3754; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12213754 - 26 Oct 2022
Cited by 10 | Viewed by 1749
Abstract
In this study, we synthesized hybrid systems based on manganese oxide@zinc oxide (Mn3O4@ZnO), using sol gel and hydrothermal methods. The hybrid materials exhibited hierarchical morphologies and structures characterized by the hexagonal phase of ZnO and the tetragonal phase of [...] Read more.
In this study, we synthesized hybrid systems based on manganese oxide@zinc oxide (Mn3O4@ZnO), using sol gel and hydrothermal methods. The hybrid materials exhibited hierarchical morphologies and structures characterized by the hexagonal phase of ZnO and the tetragonal phase of Mn3O4. The hybrid materials were tested for degradation of methylene blue (MB), methyl orange (MO), and malachite green (MG) under ultraviolet (UV) light illumination. The aim of this work was to observe the effect of various amounts of Mn3O4 in enhancing the photocatalytic properties of ZnO-based hybrid structures towards the degradation of MB, MO and MG. The ZnO photocatalyst showed better performance with an increasing amount of Mn3O4, and the degradation efficiency for the hybrid material containing the maximum amount of Mn3O4 was found to be 94.59%, 89.99%, and 97.40% for MB, MO and MG, respectively. The improvement in the performance of hybrid materials can be attributed to the high charge separation rate of electron-hole pairs, the co-catalytic role, the large number of catalytic sites, and the synergy for the production of high quantities of oxidizing radicals. The performance obtained from the various Mn3O4@ZnO hybrid materials suggest that Mn3O4 can be considered an effective co-catalyst for a wide range of photocatalytic materials such as titanium dioxide, tin oxide, and carbon-based materials, in developing practical hybrid photocatalysts for the degradation of dyes and for wastewater treatment. Full article
(This article belongs to the Special Issue Nanocatalyst for Water Splitting)
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16 pages, 20382 KiB  
Article
Psyllium-Husk-Assisted Synthesis of ZnO Microstructures with Improved Photocatalytic Properties for the Degradation of Methylene Blue (MB)
by Syed Nizam Uddin Shah Bukhari, Aqeel Ahmed Shah, Muhammad Ali Bhatti, Aneela Tahira, Iftikhar Ahmed Channa, Abdul Karim Shah, Ali Dad Chandio, Wael A. Mahdi, Sultan Alshehri, Zaffar Hussain Ibhupoto and Wen Liu
Nanomaterials 2022, 12(20), 3568; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12203568 - 12 Oct 2022
Cited by 11 | Viewed by 1770
Abstract
Wastewater from the textile industry is chronic and hazardous for the human body due to the presence of a variety of organic dyes; therefore, its complete treatment requires efficient, simple, and low cost technology. For this purpose, we grew ZnO microstructures in the [...] Read more.
Wastewater from the textile industry is chronic and hazardous for the human body due to the presence of a variety of organic dyes; therefore, its complete treatment requires efficient, simple, and low cost technology. For this purpose, we grew ZnO microstructures in the presence of psyllium husk, and the role of psyllium husk was to modify the surface of the ZnO microstructures, create defects in the semiconducting crystal structures, and to alter the morphology of the nanostructured material. The growth process involved a hydrothermal method followed by calcination in air. Additionally, the psyllium husk, after thermal combustion, added a certain value of carbon into the ZnO nanomaterial, consequently enhancing the photocatalytic activity towards the degradation of methylene blue. We also investigated the effect of varying doses of photocatalyst on the photocatalytic properties towards the photodegradation of methylene blue in aqueous solution under the illumination of ultraviolet light. The structure and morphology of the prepared ZnO microstructures were explored by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) techniques. The degradation of methylene blue was monitored under the irradiation of ultraviolet light and in the dark. Also, the degradation of methylene blue was measured with and without photocatalyst. The photodegradation of methylene blue is highly increased using the ZnO sample prepared with psyllium husk. The photodegradation efficiency is found to be approximately 99.35% for this sample. The outperforming functionality of psyllium-husk-assisted ZnO sample is attributed to large surface area of carbon material from the psyllium husk and the synergetic effect between the incorporated carbon and ZnO itself. Based on the performance of the hybrid material, it is safe to say that psyllium husk has high potential for use where surface roughness, morphology alteration, and defects in the crystal structure are vital for the enhancing the functionality of a nanostructured material. The observed performance of ZnO in the presence of psyllium husk provides evidence for the fabrication of a low cost and efficient photocatalyst for the wastewater treatment problems. Full article
(This article belongs to the Special Issue Nanocatalyst for Water Splitting)
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17 pages, 17119 KiB  
Article
Influence of Stress on Electronic and Optical Properties of Rocksalt and Wurtzite MgO–ZnO Nanocomposites with Varying Concentrations of Magnesium and Zinc
by Yin-Pai Lin, Sergei Piskunov, Laima Trinkler, Mitch Ming-Chi Chou and Liuwen Chang
Nanomaterials 2022, 12(19), 3408; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12193408 - 28 Sep 2022
Viewed by 1121
Abstract
The structural, electronic and optical properties of stressed MgO–ZnO nanocomposite alloys with concentrations of Zn and Mg varying from 0.125 to 0.875 were studied using ab initio simulations. Two crystal structures are considered for the initial MgO–ZnO alloys: the rocksalt Mg [...] Read more.
The structural, electronic and optical properties of stressed MgO–ZnO nanocomposite alloys with concentrations of Zn and Mg varying from 0.125 to 0.875 were studied using ab initio simulations. Two crystal structures are considered for the initial MgO–ZnO alloys: the rocksalt Mg1xZnxO and wurtzite Zn1xMgxO phases. For rocksalt Mg1xZnxO, the optimized structures are stable at pressures below 10 GPa. The larger the Mg concentration and pressure, the wider the Eg of the rocksalt phase. In contrast, the optimal geometries of wurtzite Zn1xMgxO reveal a diversity of possibilities, including rocksalt, wurtzite and mixed phases. These effects lead to the fact that the optical properties of wurtzite Zn1xMgxO not only demonstrate the properties of the wurtzite phase but also indicate the optical features of the rocksalt phase. In addition, mixed phases of Zn1xMgxO simultaneously provide the characteristics of both wurtzite and rocksalt phases with the same structures in different dielectric matrices. Full article
(This article belongs to the Special Issue Nanocatalyst for Water Splitting)
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12 pages, 3094 KiB  
Article
Synergy of Au–Pt for Enhancing Ethylene Photodegradation Performance of Flower-like TiO2
by Wanzhen Meng, Yunrui Zhao, Dujuan Dai, Qianqian Zhang, Zeyan Wang, Yuanyuan Liu, Zhaoke Zheng, Hefeng Cheng, Ying Dai, Baibiao Huang and Peng Wang
Nanomaterials 2022, 12(18), 3221; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12183221 - 16 Sep 2022
Cited by 2 | Viewed by 1232
Abstract
Efficient and low-cost degradation of ethylene has always been a difficult problem in the storage and transportation of fruits and vegetables. Although photocatalysis is considered to be a feasible and efficient solution for ethylene degradation, the low degradation ability of conventional catalysts for [...] Read more.
Efficient and low-cost degradation of ethylene has always been a difficult problem in the storage and transportation of fruits and vegetables. Although photocatalysis is considered to be a feasible and efficient solution for ethylene degradation, the low degradation ability of conventional catalysts for small non-polar molecules limits its application. TiO2 has the advantage of tunable microstructure, but it also has the defects of wide band gap and low utilization of sunlight. The surface plasmon resonance (SPR) effect of noble metals can effectively improve the visible light absorption range of catalysts, and the synergy of noble metals further enhances the photocatalytic ability. Herein, we developed a series of AuPt catalysts through the photo-deposition method. Benefited from the SPR effect and the synergy of Au and Pt, the efficiency of AuPt–TiO2 was 19.9, 4.64 and 2.42 times that of TiO2, Au–TiO2 and Pt–TiO2, and the photocatalytic degradation ability of AuPt–TiO2 was maintained in five cyclic stability tests. Meanwhile, the transient photocurrent spectra and PL spectra proved that the light absorption capacity and carrier separation efficiency of AuPt–TiO2 were enhanced. This work provides a new direction for enhancing non-polar small-molecule photodegradation of semiconductors. Full article
(This article belongs to the Special Issue Nanocatalyst for Water Splitting)
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16 pages, 6932 KiB  
Article
One-Dimensional P-Doped Graphitic Carbon Nitride Tube: Facile Synthesis, Effect of Doping Concentration, and Enhanced Mechanism for Photocatalytic Hydrogen Evolution
by Dazhuang Yu, Tiekun Jia, Zhao Deng, Qichen Wei, Kun Wang, Lihua Chen, Pingping Wang and Jiedong Cui
Nanomaterials 2022, 12(10), 1759; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12101759 - 21 May 2022
Cited by 9 | Viewed by 1904
Abstract
P-doped graphitic carbon nitride tubes (P-CNTS) with different P concentrations were successfully fabricated via a pre-hydrothermal in combination with a calcination process under a nitrogen atmosphere. The as-prepared samples exhibited excellent photocatalytic performance with a hydrogen production rate (HPR) of 2749.3 μmol g [...] Read more.
P-doped graphitic carbon nitride tubes (P-CNTS) with different P concentrations were successfully fabricated via a pre-hydrothermal in combination with a calcination process under a nitrogen atmosphere. The as-prepared samples exhibited excellent photocatalytic performance with a hydrogen production rate (HPR) of 2749.3 μmol g−1 h−1, which was 17.5 and 6.6 times higher than that of the bulk graphitic carbon nitride (CNB) and graphitic carbon nitride tube (CNT). The structural and textural properties of the P-CNT samples were well-investigated via a series of characterization methods. Compared with the bulk g-C3N4, the tubular structure of the doped samples was provided with a larger specific surface area (SSA) and a relatively rough interior. Besides the above, surface defects were formed due to the doping, which could act as more active sites for the hydrogen production reaction. In addition, the introduction of the P element could effectively adjust the band-gap, strengthen the harvest of visible-light, and boost the effective separation of photogenerated charges. More interestingly, these findings can open up a novel prospect for the enhancement of the photocatalytic performance of the modified g-C3N4. Full article
(This article belongs to the Special Issue Nanocatalyst for Water Splitting)
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