| 1. |
- Fan, Ke, et al.
(author)
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Amorphous WO3 induced lattice distortion for a low-cost and high-efficient electrocatalyst for overall water splitting in acid
- 2020
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In: Sustainable Energy & Fuels. - : ROYAL SOC CHEMISTRY. - 2398-4902. ; 4:4, s. 1712-1722
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Journal article (peer-reviewed)abstract
- The development of highly active and durable catalysts for water oxidation under acidic conditions is necessary but challenging for renewable energy conversion. Ir-based catalysts are highly efficient for water oxidation in acid, but their large scale application is hindered by the high cost and scarcity of iridium. Herein, we use an amorphous WO3 induced lattice distortion (AWILD) strategy to reduce the Ir content to only 2 wt% in the final material. The optimized hybrid nitrogen-doped carbon (NC)/WO3/IrO2 can efficiently catalyze water oxidation with a low overpotential of 270 mV at 10 mA cm(-2) current density (eta (10)) and a high turnover frequency of over 2 s(-1) at 300 mV overpotential in 0.5 M H2SO4, a performance that surpasses that of commercial IrO2 significantly. Introducing the layer of amorphous WO3 between IrO2 nanoparticles and NC can distort the lattice of IrO2, exposing more highly active sites for water oxidation. The AWILD effect compensates for the lower Ir content and dramatically reduces the cost of the catalyst without sacrificing the catalytic activity. Additionally, this catalyst also exhibits high activity in acid for hydrogen evolution with only 65 mV of eta (10) attributed to the AWILD effect, exhibiting efficient bifunctionality as a Janus catalyst for overall water splitting. The AWILD approach provides a novel and efficient strategy for low-cost and highly efficient electrocatalysts for acidic overall water splitting with an extremely low content of noble metals.
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| 2. |
- Fan, Ke, et al.
(author)
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Sacrificial W Facilitates Self-Reconstruction with Abundant Active Sites for Water Oxidation
- 2022
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In: Marine and Petroleum Geology. - : Wiley. - 0264-8172 .- 1873-4073. ; 138
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Journal article (peer-reviewed)abstract
- Water oxidation is an important reaction for multiple renewable energy conversion and storage-related devices and technologies. High-performance and stable electrocatalysts for the oxygen evolution reaction (OER) are urgently required. Bimetallic (oxy)hydroxides have been widely used in alkaline OER as electrocatalysts, but their activity is still not satisfactory due to insufficient active sites. In this research, A unique and efficient approach of sacrificial W to prepare CoFe (oxy)hydroxides with abundant active species for OER is presented. Multiple ex situ and operando/in situ characterizations have validated the self-reconstruction of the as-prepared CoFeW sulfides to CoFe (oxy) hydroxides in alkaline OER with synchronous W etching. Experiments and theoretical calculations show that the sacrificial W in this process induces metal cation vacancies, which facilitates the in situ transformation of the intermediate metal hydroxide to CoFe-OOH with more high-valence Co(III), thus creating abundant active species for OER. The Co(III)-rich environment endows the in situ formed CoFe oxyhydroxide with high catalytic activity for OER on a simple flat glassy carbon electrode, outperforming those not treated by the sacrificial W procedure. This research demonstrates the influence of etching W on the electrocatalytic performance, and provides a low-cost means to improve the active sites of the in situ self-reconstructed bimetallic oxyhydroxides for OER.
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| 3. |
- Fan, Lizhou, et al.
(author)
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2D MnOx composite catalysts inspired by natural OEC for efficient catalyticwater oxidation
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Other publication (other academic/artistic)abstract
- Birnessite MnOx is a close inorganic model of natural oxygen-evolving complex (OEC) that hasbeen widely investigated for catalytic water oxidation, yet its activity is limited by the pooractive site exposure and sluggish charge transfer. Herein, starting from typical birnessite MnOx,we fabricated a hybrid of 2D manganese oxide nanosheets and pyridyl modified graphene(MnOx-NS/py-G) for electrocatalytic water oxidation. Benefiting from the synergy of structuralexfoliation, graphene substrate and molecular pyridyl modification, the MnOx-NS/py-G exhibitsabundant catalytically active sites exposure, fast electron transport, and promoted proton transferat catalyst surface, which imitates the key features of natural OEC. Consequently, theMnOx-NS/py-G reached over 600 times higher activity compared to the typical birnessite MnOx.Inspired by nature, this work provides a well-designed and effective strategy to develop highlyactive manganese oxide-based water oxidation catalysts.
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| 4. |
- Fan, Lizhou, et al.
(author)
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Holistic functional biomimetics : a key to make an efficient electrocatalyst for water oxidation
- 2023
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 11:20, s. 10669-10676
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Journal article (peer-reviewed)abstract
- Water oxidation is the holy grail reaction of natural and artificial photosynthesis. How to design an efficient water-oxidation catalyst remains a long-term challenge for solar fuel production. The rate of water oxidation in photosystem II by the oxygen-evolving complex (OEC) Mn4CaO5 cluster is as high as 100-400 s−1. Mimicking the structures of the OEC is a straightforward strategy to design water-oxidation catalysts. However, the high efficiency of the OEC relies on not only its highly active site but also its holistic system for well-organized electron transfer and proton transport. Lacking such a holistic functional system makes δ-MnO2 a poor water-oxidation catalyst, although the local structure of δ-MnO2 is similar to that of the Mn4CaO5 cluster. Electrocatalysts simultaneously imitating the catalytically active sites, fast electron transfer, and promoted proton transport in a natural OEC have been rarely reported. The significance of the synergy of a holistic system is underrated in the design of water-oxidation catalysts. In this work, we fabricated holistic functional biomimetic composites of two-dimensional manganese oxide nanosheets and pyridyl-modified graphene (MnOx-NS/py-G) for electrocatalytic water oxidation. MnOx-NS/py-G simultaneously imitates the synergy of catalytically active sites, fast electron transfer, and promoted proton transport in a natural OEC, resulting in overall 600 times higher activity than that of typical δ-MnO2. This work demonstrates the significance of holistic functional biomimetic design and guides the development of highly active electrocatalysts for small molecule activation related to solar energy storage.
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| 5. |
- Fan, Lizhou, et al.
(author)
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3D Core-Shell NiFeCr Catalyst on a Cu Nanoarray for Water Oxidation : Synergy between Structural and Electronic Modulation
- 2018
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In: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 3:12, s. 2865-2874
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Journal article (peer-reviewed)abstract
- Low cost transition metal-based electrocatalysts for water oxidation and understanding their structure-activity relationship are greatly desired for clean and sustainable chemical fuel production. Herein, a core-shell (CS) NiFeCr metal/metal hydroxide catalyst was fabricated on a 3D Cu nanoarray by a simple electrodeposition-activation method. A synergistic promotion effect between electronic structure modulation and nanostructure regulation was presented on a CS-NiFeCr oxygen evolution reaction (OER) catalyst: the 3D nanoarchitecture facilitates the mass transport process, the in situ formed interface metal/metal hydroxide heterojunction accelerates the electron transfer, and the electronic structure modulation by Cr incorporation improves the reaction kinetics. Benefiting from the synergy between structural and electronic modulation, the catalyst shows excellent activity toward water oxidation under alkaline conditions: overpotential of 200 mV at 10 mA/cm(2) current density and Tafel slope of 28 mV/dec. This work opens up a new window for understanding the structure-activity relationship of OER catalysts and encourages new strategies for development of more advanced OER catalysts.
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| 6. |
- Fan, Lizhou, et al.
(author)
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Molecular Functionalization of NiO Nanocatalyst for Enhanced Water Oxidation by Electronic Structure Engineering
- 2020
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:22, s. 5901-5909
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Journal article (peer-reviewed)abstract
- Tuning the local environment of nanomaterial-based catalysts has emerged as an effective approach to optimize their oxygen evolution reaction (OER) performance, yet the controlled electronic modulation around surface active sites remains a great challenge. Herein, directed electronic modulation of NiO nanoparticles was achieved by simple surface molecular modification with small organic molecules. By adjusting the electronic properties of modifying molecules, the local electronic structure was rationally tailored and a close electronic structure-activity relationship was discovered: the increasing electron-withdrawing modification readily decreased the electron density around surface Ni sites, accelerating the reaction kinetics and improving OER activity, and vice versa. Detailed investigation by operando Raman spectroelectrochemistry revealed that the electron-withdrawing modification facilitates the charge-transfer kinetics, stimulates the catalyst reconstruction, and promotes abundant high-valent gamma-NiOOH reactive species generation. The NiO-C(6)F(5)catalyst, with the optimized electronic environment, exhibited superior performance towards water oxidation. This work provides a well-designed and effective approach for heterogeneous catalyst fabrication under the molecular level.
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| 7. |
- Fan, Lizhou, et al.
(author)
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Promoting the Fe(VI) active species generation by structural and electronic modulation of efficient iron oxide based water oxidation catalyst without Ni or Co
- 2020
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In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 72
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Journal article (peer-reviewed)abstract
- Fe is considered as a promising alternative for OER catalysts owing to its high natural abundance and low cost. Due to the low conductivity and sluggish catalytic kinetics, the catalytic efficiency of Fe-rich catalysts is far from less abundant Ni, Co-rich alternatives and has been hardly improved without the involvement of Ni or Co. The lower activity of Fe-rich catalysts renders the real active center of state-of-the-art NiFe, CoFe catalyst in long-term scientific debate, despite of detection of Fe-based active intermediates in these catalysts during catalytic process. In the present work, we fabricated a series of sub-5 nm Fe1-yCryOx nanocatalysts via a simple solvothermal method, achieving systematically promoted high-valent Fe(VI) species generation by structural and electronic modulation, displaying highly active OER performance without involvement of Ni or Co. Detailed investigation revealed that the high OER activity is related to the ultrasmall nanoparticle size that promotes abundant edge- and corner-site exposure at catalyst surface, which involves in OER as highly reactive site; and the incorporated Cr ions that remarkably accelerate the charge transfer kinetics, providing an effective conduit as well as suitable host for high-valent active intermediate. This work reveals the structural prerequisites for efficient Fe-rich OER catalyst fabrication, inspiring deeper understanding of the structure-activity relationship as well as OER mechanism of Fe-based catalysts.
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| 8. |
- Fan, Lizhou
(author)
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Towards Artificial Photosynthesis: Exploration of Efficient First-Row Transition Metal-Based Water Oxidation Catalysts
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Artificial photosynthesis provides a promising strategy for sustainable energy harvesting, yet its overall efficiency is limited by the water oxidation reaction. The subject of this thesis focuses on the exploration of highly efficient cost-effective heterogeneous catalysts for water oxidation, and the investigation of essential catalyst structure-activity relationships.Chapters 1 and 2 present a brief introduction on heterogeneous catalysts for water oxidation, including selected state-of-the-art catalysts, methodologies for activity improvement, and mechanistic investigations. The characterization methods used in this thesis are also demonstrated.In chapter 3, a molecular functionalization approach is developed to rationally modify the electronic structure of NiO catalyst, by which the water oxidation activity is systematically tailored. These studies correspond to the question: “How to rationally adjust the catalytic performance of heterogeneous catalysts?”In chapter 4, to lower the catalyst cost, a Fe-based Fe0.65Cr0.35Ox nanocatalyst is fabricated by structural and electronic modulation, which shows considerable water oxidation activity. These studies target the question: “How to fabricate an efficient Fe-based water oxidation catalyst?”In chapter 5, a bio-inspired Mn-based catalyst is presented. The catalyst successfully imitates the key features of the natural oxygen evolving complex, achieving dramatically improved water oxidation activity. These studies correspond to the question: “How to improve the catalytic activity of Mn-based water oxidation catalysts?”Finally, in chapter 6, a 3D NiFeCr/Cu nanoarray electrode is constructed by structural engineering, which exhibits extremely high water oxidation activity. These studies correspond to the question: “How to fabricate an efficient catalytic electrode for water oxidation?”
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| 9. |
- Guo, Yaxiao, et al.
(author)
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Boosting nitrogen reduction reaction by bio-inspired FeMoS containing hybrid electrocatalyst over a wide pH range
- 2019
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In: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 62, s. 282-288
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Journal article (peer-reviewed)abstract
- A facile preparation of bio-inspired and morphology controllable catalytic electrode FeS@MoS2/CFC, featuring a carbon fiber cloth (CFC) covered with FeS dotted MoS2 nanosheets, has been established. Synergy between the CFC as a self-standing conductive substrate and the FeS nanoparticle dotted MoS2 nanosheets with abundant active sites makes the noble-metal-free catalytic electrode FeS@MoS2/CFC highly efficient in nitrogen reduction reaction (NRR), with an ammonia production rate of 8.45 mu g h(-1) cm(-2) and excellent long-term stability at -0.5 V in pH neutral electrolyte. Further electrolysis in acidic and alkaline electrolytes revealed the overall NRR catalytic activity of this electrode over a wide pH range.
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| 10. |
- Guo, Yaxiao, et al.
(author)
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Molybdenum and boron synergistically boosting efficient electrochemical nitrogen fixation
- 2020
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In: Nano Energy. - : Elsevier Ltd. - 2211-2855 .- 2211-3282. ; 78
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Journal article (peer-reviewed)abstract
- Ammonia production consumes ~2% of the annual worldwide energy supply, therefore strategic alternatives for the energy-intensive ammonia synthesis through the Haber-Bosch process are of great importance to reduce our carbon footprint. Inspired by MoFe-nitrogenase and the energy-efficient and industrially feasible electrocatalytic synthesis of ammonia, we herein establish a catalytic electrode for artificial nitrogen fixation, featuring a carbon fiber cloth fully grafted by boron-doped molybdenum disulfide (B-MoS2/CFC) nanosheets. An excellent ammonia production rate of 44.09 μg h–1 cm–2 is obtained at −0.2 V versus the reversible hydrogen electrode (RHE), whilst maintaining one of the best reported Faradaic efficiency (FE) of 21.72% in acidic aqueous electrolyte (0.1 M HCl). Further applying a more negative potential of −0.25 V renders the best ammonia production rate of 50.51 μg h–1 cm–2. A strong-weak electron polarization (SWEP) pair from the different electron accepting and back-donating capacities of boron and molybdenum (2p shell for boron and 5d shell for molybdenum) is proposed to facilitate greatly the adsorption of non-polar dinitrogen gas via N≡N bond polarization and the first protonation with large driving force. In addition, for the first time a visible light driven photo-electrochemical (PEC) cell for overall production of ammonia, hydrogen and oxygen from water + nitrogen, is demonstrated by coupling a bismuth vanadate BiVO4 photo-anode with the B-MoS2/CFC catalytic cathode.
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