If you like it, follow us and subscribe to more of the latest news
First author: Yang Min
Corresponding authors: Professor Yu Le, Professor Lou Xiongwen
Communication units: Beijing University of Chemical Technology, Nanyang Technological University, Singapore
Thesis DOI: 10.1002/advs.202105135
Full text at a glance
Recently, Professor Yu Le of Beijing University of Chemical Technology and Professor Xiongwen Lou of Nanyang Technological University in Singapore published a review article entitled "Design and Synthesis of Hollow Nanostructures for Electrochemical Water Splitting" in the internationally renowned journal Advanced Science. This paper summarizes the latest research progress of hollow electrolyzed water catalysts in structural design, focusing on the representative work of hollow catalytic materials with single-layer, multi-layer and open-frame structures and catalytic materials based on hollow host composite structures for electrolysis of water. In addition, the application of hollow nanostructures in the coupling reaction of electrolyzed water and organic matter synthesis is also briefly introduced. Finally, the research prospects of hollow electrolyzed water catalysts are prospected.
Background
The development of high-efficiency electrocatalysts is of great significance to promote the development of large-scale electrolysis of water to hydrogen production technology. Due to its high specific surface area, well-defined internal spatial structure and adjustable chemical composition, hollow nanostructures show good application prospects in the field of electrolyzed water. On the one hand, the hollow material can be used directly as a catalyst for electrolysis of water, and on the other hand, it can also be used as a carrier on the inner/outer surface, pores/channels, internal cavity to support the active species, or to encapsulate the active species in a hollow host frame, thereby constructing a composite structure of the electrolyzed water catalyst.
Figure 1. Schematic diagram of the structure of the hollow electrolyzed water catalyst
Fig. 1 each figure is (I) a single-layer hollow catalyst, (II) a multilayer hollow catalyst, (III) a composite catalyst based on a hollow host, and (IV) a mixed hollow reactor.
Graphic and text analysis
The hollow material acts directly as a catalyst for electrolysis of water
When hollow materials are directly used as electrocatalyst materials, they can be divided into hollow electrolyzed water catalysts with single-layer, multi-layer and open frame structures according to the geometry and complexity of composition.
Figure 2. Single-layer hollow structure
Single-layer hollow structure can be divided into primary single-layer hollow structure and multi-level single-layer hollow structure. Fig. 2a-d shows Ni2P hollow spheres for highly efficient acidic water electrolysis to hydrogen production (HER). Fig. 2e-g shows a β-Mo2C multi-stage hollow nanotube assembled from ultra-thin nanosheets for both highly efficient acidic and alkaline HER. Fig. 2h shows the CoMoS4 hollow nanoprism. Fig. 2i-j shows a multi-stage Ni-Co-MoS2 hollow nanoceller assembled from MoS2 nanosheets for highly efficient acidIC HER.
Figure 3. Single-layer hollow structure
Fig. 3a-c shows Co3O4 multi-stage hollow microtube array (Co3O4-MTA) used as an electrocatalyst for highly efficient alkaline electrolysis of aquatic oxygen reaction (OER). Fig. 3d-f shows a α-Ni(OH)2 multi-stage hollow microsphere assembled from ultra-thin nanosheets as an efficient alkaline OER electrocatalyst. Fig. 2g-i is a graded hollow nanoprism assembled from ultra-thin Ni-Fe LDH nanosheets as a highly efficient alkaline OER electrocatalyst.
Figure 4. Multi-layer hollow structure
Fig. 4a-c shows an Ni-Fe LDH nanocache with an adjustable shell assembled from ultra-thin nanosheets and its application in high-efficiency OER. Fig. 4d-h shows the shell structure of multilayer hollow CoPs that continuously regulate to improve the mass transfer process of HER and OER.
Figure 5. Frame hollow structure
Fig. 5a-d shows the synthesis of Pt3Ni nanoparticles with an open frame structure and electrodeposition ni(OH)2 on its surface to promote alkaline HER performance. Fig. 5e-h shows the IrNiCu bilayer open nano polyhedral frame structure (IrNiCu DNF) as a highly efficient acidic OER electrocatalyst.
Figure 6. Frame hollow structure
Fig. 6a-d shows the selective etch synthesis of Ni-Co PBA cubic hollow cage structure and its application in highly efficient alkaline OER. Fig. 6e-h shows a complex ordered framework-like superstructure (KCoFe-1 NAFSs) assembled by Co-Fe PBA nanocrystals and its application in highly efficient alkaline OER.
Hollow composite electrolyzed water catalyst
In addition to being used directly as catalyst materials, hollow nanostructures can also be used as catalysts for host materials to construct composite structures. According to whether the spatial position of the active species is clear, the hollow composite electrolyzed water catalyst can be further divided into the following two categories. First, the spatially well-positioned composite electrocatalyst, in which the active component may be confined to the internal cavity of the hollow host, the porous shell, and the inner and outer surfaces. The second is a composite electrocatalyst with ambiguous spatial position, for which the hollow material can be used as a secondary catalyst or additive to promote the electrolysis of water reaction together with the active component.
Figure 7. Spatially well-positioned hollow composite catalyst
Figure 7a, b shows a mildly oxidized multi-walled carbon nanotube-supported NiFe-LDH nanosheet (Ni-Fe-LDH/CNT) used as a highly efficient alkaline OER electrocatalyst. Figure 7c-e shows ZIF-67-derived hollow nitrogen-doped carbon nanotubes and their alkaline OER properties. Fig. 7f-h constructs Janus hollow graphene (Ni-N4/GHSs/Fe-N4) for selective oxygen electrocatalysis at ni-N4 and Fe-N4 diatomic centers.
Figure 8. Hollow composite catalyst with ambiguous spatial position
Figure 8a-d shows a Ni-doped FeP-carbon composite (NFP/C) hollow nanorod achieving high efficiency HER in the full pH range. Fig. 8e-h shows an ultra-thin conductive Cu-MOF layer fully supported on the surface of a synergistic [Fe(OH)x] nanobox (Fe(OH)x@Cu-MOF) to achieve highly effective alkaline HER.
Innovative strategies for electrolyzing water
Replacing OER with a thermodynamically more advantageous organic oxidation reaction and coupling it to the cathode HER can reduce the voltage input during electrolysis and simultaneously achieve the production of high value-added products and high-purity hydrogen.
Figure 9. Electrolysis of water is coupled with the oxidation of organic matter
Fig. 9a-d is a phosphorus-substituted cobalt sulfide nickel egg yolk-shell hollow nanosphere (P-CoNi2S4 YSSs) that achieves efficient water electrolysis and urea electrolysis at the same time. Fig. 9e-h shows a porous carbon coated MoO2-FeP heterojunction (MoO2-FeP@C) while achieving a highly efficient alkali HER and 5-hydroxymethyl furfural electrooxidation reaction.
Summary and outlook
Figure 10. Hollow catalysts are used for the progression of electrolyzed water reactions
This review summarizes in detail the important progress of hollow nanostructures directly as catalyst materials and as host materials for the construction of composite electrolyzed water catalysts. In addition, the paper also introduces and comments on the application of hollow materials to the oxidation reaction of electrolyzed water-coupled organic matter. At present, although the design and synthesis of hollow electrolyzed water catalysts have made great progress and remarkable achievements, there are still some problems that need to be solved in future research, such as:
1. Further develop economical and large-scale synthesis technology. Laboratory-grade research needs to be closely integrated with industrial needs to prepare highly active and long-life hollow electrolyzed water catalysts.
2. From the perspective of structural design, in order to clarify the relationship between the complex effects of hollow structures (strain effect, group effect, synergy effect, etc.) and the electrocatalytic water decomposition performance, it is necessary to deeply understand the basic science of materials and the mechanism of chemical reaction.
3. From the perspective of reactor design optimization, the role of spatiotemporal orderliness of hollow catalysts in mass transfer, storage and release needs further theoretical prediction and experimental verification.
4. From the performance point of view, the development of advanced in situ high-resolution characterization technology helps to analyze the reasons for the performance change of hollow electrolyzed water catalysts in the actual reaction process.
5. For the system coupled with the electrolysis of water and organic oxidation, it is necessary to accurately design the structure and control the components to adjust the surface chemistry of the hollow electrocatalyst to obtain the target product under the specific reaction.
Corresponding Author Introduction
Yu Le, Professor of Beijing University of Chemical Technology, Doctoral Supervisor. In 2018, he was selected into the list of globally highly cited scientists in Clarivate's interdisciplinary fields, and in 2019, 2020 and 2021, he was selected into the list of global highly cited scientists in the dual fields of Clarivate Chemistry and Materials Science for three consecutive years. He was awarded the 2016, 2017 and 2018 Journal of Materials Chemistry A Outstanding Reviewer. He is currently a member of the Youth Editorial Board of Energy & Environmental Materials, Green Energy & Environment, Acta Physico-Chemical Sinica and Rare Metals, and an editorial board member of Shandong Chemical Industry. He is mainly engaged in the design and synthesis of new micro and nano structure functional materials, especially the optimal design and synthesis exploration of hollow nano functional materials, and studies the application of functional nanomaterials in the field of electrochemical energy storage conversion, such as lithium/sodium capacitors, batteries, electrocatalysis, etc. As first author/co-author/corresponding author in Science Advances, Advanced Materials, Angewandte Chemie International Edition, Advanced Energy Materials, Advanced Functional Materials, Accounts of Chemical Research, Energy & Environmental Science, Advanced Science and other international academic journals have published a series of articles, including 48 ESI highly cited papers, 11 cover/inner cover papers, 1 title page paper and 2 VIP papers, SCI has a total of more than 19,000 citations, and the H-index is 69.
Homepage of the research group
https://www.x-mol.com/groups/Yu_Le
Prof Lo Hung Man is a Cheng Tsang Man Chair Professor at the School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore. Since 2014, he has been rated as a highly cited researcher by Thomson Reuters for 8 consecutive years. He was awarded the Esso Gold Medal, Austin Hooey Prize and Liu Memorial Award for his outstanding work, as well as the Young Scientist Award of the National Academy of Sciences of Singapore 2012. He is currently Associate Editor of Science Advances, Associate Editor of Journal of Materials Chemistry A, and Member of the Editorial Board of SmallMethods. The main research direction is the application of nano-functional materials, especially hollow nanomaterials in the field of energy. Prof. Lo teaches at Science, Nature Energy, Science Advances, Angewandte Chemie International Edition, Advanced Materials, Journal of the American Chemical Society, Nature Communications, Chem, Joule, Energy & Environmental Science, Advanced Energy Materials and other international top journals have published more than 360 papers, with a cumulative citation of more than 106,000 times, and the H index is as high as 192.
http://www.ntu.edu.sg/home/xwlou/
Literature source
M. Yang, C. H. Zhang, N. W. Li, D. Y.Luan, L. Yu*, X. W. Lou*, Design and Synthesis of Hollow Nanostructures for Electrochemical Water Splitting, Adv. Sci. 2022,DOI: 10.1002/advs.202105135.
https://doi.org/10.1002/advs.202105135
statement