1
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Li K, Yin Y, Diao P. Enhancing Photoelectrochemical Water Oxidation on WO 3 via Electrochromic Modulation: Universal Effects and Mechanistic Insights. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2402474. [PMID: 38822710 DOI: 10.1002/smll.202402474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 05/19/2024] [Indexed: 06/03/2024]
Abstract
Although WO3 exhibits both electrochromic and photoelectrochemical (PEC) properties, there is no research conducted to investigate the correlation between them. The study herein reports the electrochromic enhancement of PEC activity on WO3. The electrochromic WO3 (e-WO3) exhibits a significantly enhanced activity for PEC water oxidation compared to raw WO3 (r-WO3), with a limiting photocurrent density three times that of r-WO3. The electrochromic enhancement of PEC activity is universal and independent of the type of cations inserted during electrochromism. Decoloring reduces the PEC activity but a simple re-coloring restores the activity to its maximum value. Electrochromism induces large amounts of oxygen vacancies and surface states, the former improving the electron density of WO3 and the latter facilitating the hole transfer across e-WO3/electrolyte interface. It is proved that the electrochromic enhancement effect is due to the significantly improved electron-hole separation efficiency and the charge transfer efficiency across the WO3/electrolyte interface.
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Affiliation(s)
- Kangqiang Li
- Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Yefeng Yin
- Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Peng Diao
- Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
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2
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Fu H, Bai Y, Lian Y, Hu Y, Zhao J, Zhang H. Oxygen-Deficient FeNbO 4-x In-Situ Growth in Honey-Derived N-Doping Porous Carbon for Overall Water Splitting. CHEMSUSCHEM 2024; 17:e202400162. [PMID: 38556462 DOI: 10.1002/cssc.202400162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/12/2024] [Accepted: 03/29/2024] [Indexed: 04/02/2024]
Abstract
It is still a great challenge to reasonably design green, low cost, high activity and good stability catalysts for overall water splitting (OWS). Here, we introduce a novel catalyst with ferric niobate (FeNbO4) in-situ growing in honey-derived porous carbon of high specific surface area, and its catalytic activity is further enhanced by micro-regulation (oxygen vacancy and N-doping). From the experimental results and density functional theory (DFT) calculations, the oxygen vacancy in catalyst FeNbO4-x@NC regulates the local charge density of active site, thus increasing conductivity and optimizing hydrogen/oxygen species adsorption energy. FeNbO4 in-situ grows within N-doping honey-derived porous carbon, which can enhance active specific surface area exposure, strengthen gaseous substances escape rate, and accelerate electrons/ions transfer and electrolytes diffusion. Moreover, in-situ Raman also confirms O-species generation in oxygen evolution reaction (OER). As a result, the catalyst FeNbO4-x@NC shows good electrochemical performance in OER, HER and OWS.
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Affiliation(s)
- Hongliang Fu
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, 225002, PR China
| | - Yongqing Bai
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, 225002, PR China
| | - Yue Lian
- School of Chemistry & Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051, P. R. China
| | - Yongfeng Hu
- Department of Chemical Engineering, University of Saskatchewan, Saskatoon, S7N 2V3, Canada
| | - Jing Zhao
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, 225002, PR China
| | - Huaihao Zhang
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, 225002, PR China
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3
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Wang X, Santos-Carballal D, de Leeuw NH. Cation doping and oxygen vacancies in the orthorhombic FeNbO4 material for solid oxide fuel cell applications: A density functional theory study. J Chem Phys 2024; 160:154713. [PMID: 38634493 DOI: 10.1063/5.0192749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/22/2024] [Indexed: 04/19/2024] Open
Abstract
The orthorhombic phase of FeNbO4, a promising anode material for solid oxide fuel cells (SOFCs), exhibits good catalytic activity toward hydrogen oxidation. However, the low electronic conductivity of the material specifically in the pure structure without defects or dopants limits its practical applications as an SOFC anode. In this study, we have employed density functional theory (DFT + U) calculations to explore the bulk and electronic properties of two types of doped structures, Fe0.9375A0.0625NbO4 and FeNb0.9375B0.0625O4 (A, B = Ti, V, Cr, Mn, Co, Ni) and the oxygen-deficient structures Fe0.9375A0.0625NbO3.9375 and FeNb0.9375B0.0625O3.9375, where the dopant is positioned in the first nearest neighbor site to the oxygen vacancy. Our DFT simulations have revealed that doping in the Fe sites is energetically favorable compared to doping in the Nb site, resulting in significant volume expansion. The doping process generally requires less energy when the O-vacancy is surrounded by one Fe and two Nb ions. The simulated projected density of states of the oxygen-deficient structures indicates that doping in the Fe site, particularly with Ti and V, considerably narrows the bandgap to ∼0.5 eV, whereas doping with Co at the Nb sites generates acceptor levels close to 0 eV. Both doping schemes, therefore, enhance electron conduction during SOFC operation.
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Affiliation(s)
- Xingyu Wang
- School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Nora H de Leeuw
- School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
- Department of Earth Sciences, Utrecht University, 3584 CB Utrecht, The Netherlands
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4
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Chai H, Gao L, Jin J. Revealing the Essential Role of Iron Phosphide and its Surface-Evolved Species in the Photoelectrochemical Water Oxidation by Gd-Doped Hematite Photoanode. CHEMSUSCHEM 2022; 15:e202201030. [PMID: 35761757 DOI: 10.1002/cssc.202201030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/24/2022] [Indexed: 06/15/2023]
Abstract
Phosphates are easily derived from transition metal phosphides under natural conditions, and the real roles of these two in catalytic reactions are not yet clear. Here, a multiphase FeP/Gd-Fe2 O3 shell-core structure photoanode was constructed and explored regarding the real role of FeP and its surface-reconstructed iron phosphate (Fe-Pi) in photoelectrochemical water oxidation. The FeP/Gd-Fe2 O3 photoanode exhibited an excellent photocurrent density of 2.56 mA cm-2 at 1.23 V versus the reversible hydrogen electrode, up to 4 times greater than those of the pristine α-Fe2 O3 (0.64 mA cm-2 ). Detailed studies showed that FeP could act as a photosensitizer to enhance light absorption and as a conductive layer to accelerate charge transfer. The FeP significantly enhanced the incident photon-to-current conversion efficiency of the photoanode and improved the electron transition within the photoanode. Naturally evolved Fe-Pi on the surface provided more active sites for water oxidation. They effectively passivated the surface capture state and synergistically inhibited the electron-hole recombination. Moreover, the in-situ constructed multiphase catalyst had a smaller interfacial contact resistance than the intentionally decorative cocatalyst. This work provides new insight into the understanding of the essential role of transition metal phosphides and their surface-reconstructed species in catalytic reactions.
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Affiliation(s)
- Huan Chai
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Lili Gao
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Jun Jin
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
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5
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Zhang H, Ahn CW, Park JY, Ok JW, Sung JY, Jin JS, Kim HG, Lee JS. Healing Ion-Implanted Semiconductors by Hybrid Microwave Annealing: Activation of Nitrogen-Implanted TiO 2. J Phys Chem Lett 2022; 13:3878-3885. [PMID: 35470660 DOI: 10.1021/acs.jpclett.2c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In order to recover the damaged structure of a nitrogen-implanted TiO2 (N-I-TiO2) photoanode, hybrid microwave annealing (HMA) is proposed as an alternative postannealing process instead of conventional thermal annealing (CTA). Compared to CTA, HMA provides distinctive advantages: (i) facile transformation of the interstitial N-N states into substitutional N-Ti states, (ii) better preservation of the ion-implanted nitrogen in TiO2, and (iii) effective alleviation of lattice strain and reconstruction of the broken bonds. As a result, the HMA-activated photoanode improves the photocurrent density by a factor of ∼3.2 from 0.29 to 0.93 mA cm-2 at 1.23 VRHE and the incident photon-to-current conversion efficiency (IPCE) from ∼2.9% to ∼10.5% at 430 nm relative to those of the as-prepared N-I-TiO2 photoanode in photoelectrochemical water oxidation, which are much better than those of the CTA-activated photoanode (0.58 mA cm-2 at 1.23 VRHE and IPCE of 5.7% at 430 nm), especially in the visible light region (≥420 nm).
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Affiliation(s)
- Hemin Zhang
- College of Materials Science and Engineering, Sichuan University, Engineering Research Center of Alternative Energy Materials and Devices, Ministry of Education, Chengdu 610065, China
| | - Chang Won Ahn
- Department of Physics, University of Ulsan, Ulsan, 680-749, Republic of Korea
| | - Jin Yong Park
- Busan Center, Korea Basic Science Institute, Busan, 609-735, Republic of Korea
| | - Jung-Woo Ok
- Busan Center, Korea Basic Science Institute, Busan, 609-735, Republic of Korea
| | - Ji Yeong Sung
- Busan Center, Korea Basic Science Institute, Busan, 609-735, Republic of Korea
| | - Jong Sung Jin
- Busan Center, Korea Basic Science Institute, Busan, 609-735, Republic of Korea
| | - Hyun Gyu Kim
- Busan Center, Korea Basic Science Institute, Busan, 609-735, Republic of Korea
| | - Jae Sung Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
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6
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Kang K, Zhang H, Kim JH, Byun WJ, Lee JS. An in situ fluorine and ex situ titanium two-step co-doping strategy for efficient solar water splitting by hematite photoanodes. NANOSCALE ADVANCES 2022; 4:1659-1667. [PMID: 36134374 PMCID: PMC9418710 DOI: 10.1039/d2na00029f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/11/2022] [Indexed: 06/16/2023]
Abstract
A unique two-step co-doping strategy of in situ fluorine doping followed by ex situ titanium doping enhances the performance of the hematite photoanode in photoelectrochemical water splitting much more effectively than single-step co-doping strategies that are either all in situ or all ex situ. The optimized fluorine, titanium co-doped Fe2O3 photoanode without any cocatalyst achieves 1.61 mA cm-2 at 1.23 VRHE under 100 mW cm-2 solar irradiation, which is ∼2 and 3 times those of titanium or fluorine singly-doped Fe2O3 photoanodes, respectively. The promotional effect is attributed to the synergy of the two dopants, in which the doped fluorine anion substitutes oxygen of Fe2O3 to increase the positive charges of iron sites, while the doped titanium cation substitutes iron to increase free electrons. Moreover, excess titanium on the surface suppresses the drain of in situ doped fluorine and agglomeration of hematite during the high-temperature annealing process, and passivates the surface trap states to further promote the synergy effects of the two dopants.
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Affiliation(s)
- Kyoungwoong Kang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) 50 UNIST-gil Ulsan 44919 Republic of Korea
| | - Hemin Zhang
- College of Materials Science and Engineering, Sichuan University Chengdu 610065 China
| | - Jeong Hun Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) 50 UNIST-gil Ulsan 44919 Republic of Korea
| | - Woo Jin Byun
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) 50 UNIST-gil Ulsan 44919 Republic of Korea
| | - Jae Sung Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) 50 UNIST-gil Ulsan 44919 Republic of Korea
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7
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Chai H, Wang S, Wang X, Ma J, Jin J. Modulation of the Chemical Microenvironment at the Hematite-Based Photoanode Interface with a Covalent Triazine Framework for Efficient Photoelectrochemical Water Oxidation. ACS Catal 2022. [DOI: 10.1021/acscatal.2c00285] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Huan Chai
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Shuoshuo Wang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Xu Wang
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory for Catalytic Conversion of Carbon Resources, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Jiantai Ma
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Jun Jin
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
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8
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Parveh F, Yourdkhani A, Poursalehi R. Photoelectrochemical properties of single-grain hematite films grown by electric-field-assisted liquid phase deposition. Dalton Trans 2022; 51:17255-17262. [DOI: 10.1039/d2dt02475f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article reports a modification of the conventional liquid phase deposition (C-LPD) method for the single-grain deposition of α-Fe2O3 (hematite) films into an electric-field-assisted liquid phase deposition (EA-LPD).
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Affiliation(s)
- Fatemeh Parveh
- Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran
| | - Amin Yourdkhani
- Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran
| | - Reza Poursalehi
- Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran
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9
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Bu Q, Zhao Q, Lu G, Zhu X, Zhang Y, Xie T, Liu Q, Jiang J. An efficient strategy to boost the directed migration of photogenerated holes by introducing phthalocyanine as a hole extraction layer. Inorg Chem Front 2022. [DOI: 10.1039/d2qi00701k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phthalocyanine with adjustable band energy and a binding group acts as a hole extraction layer to accelerate hole transfer from Ti-Fe2O3 to CoPi, and thus improves the PEC water oxidation performance of Ti-Fe2O3.
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Affiliation(s)
- Qijing Bu
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, P. R. China
| | - Qifeng Zhao
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, P. R. China
| | - Guang Lu
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, P. R. China
| | - Xixi Zhu
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, P. R. China
| | - Yuexing Zhang
- College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, P. R. China
| | - Tengfeng Xie
- College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Qingyun Liu
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, P. R. China
| | - Jianzhuang Jiang
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
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10
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Zhou D, Fan K. Recent strategies to enhance the efficiency of hematite photoanodes in photoelectrochemical water splitting. CHINESE JOURNAL OF CATALYSIS 2021. [DOI: 10.1016/s1872-2067(20)63712-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Hussein Ahmed S, Bakiro M, Alzamly A. Photocatalytic Activities of FeNbO 4/NH 2-MIL-125(Ti) Composites toward the Cycloaddition of CO 2 to Propylene Oxide. Molecules 2021; 26:1693. [PMID: 33803019 PMCID: PMC8002832 DOI: 10.3390/molecules26061693] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/13/2021] [Accepted: 03/15/2021] [Indexed: 11/24/2022] Open
Abstract
Photocatalytic utilization of CO2 in the production of value-added chemicals has presented a recent green alternative for CO2 fixation. In this regard, three FeNbO4/NH2-MIL-125(Ti) composites of different mole ratios were synthesized, characterized using Powder X-ray diffraction (PXRD), UV-vis diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). PXRD patterns confirm the co-existence of the parent components in the prepared composites. Moreover, the surface area increased as the mole percent of NH2-MIL-125(Ti) in the composites increased due to the large surface area of NH2-MIL-125(Ti). Prepared composites were investigated for the photocatalytic insertion of CO2 into propylene oxide. FeNbO4(75%)/NH2-MIL-125(Ti)(25%) showed the highest percent yield of 52% compared to the other two composites. Results demonstrate the cooperative mechanism between FeNbO4 and NH2-MIL-125(Ti) and that the reaction proceeded photocatalytically.
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Affiliation(s)
| | | | - Ahmed Alzamly
- Department of Chemistry, UAE University, Al-Ain 15551, United Arab Emirates; (S.H.A.); (M.B.)
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12
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Hong DH, Reddy DA, Reddy KAJ, Gopannagari M, Kumar DP, Kim TK. Synergetic catalytic behavior of dual metal-organic framework coated hematite photoanode for photoelectrochemical water splitting performance. J Catal 2020. [DOI: 10.1016/j.jcat.2020.09.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Guo Q, Luo H, Zhang J, Ruan Q, Prakash Periasamy A, Fang Y, Xie Z, Li X, Wang X, Tang J, Briscoe J, Titirici M, Jorge AB. The role of carbon dots - derived underlayer in hematite photoanodes. NANOSCALE 2020; 12:20220-20229. [PMID: 33000831 DOI: 10.1039/d0nr06139e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Hematite is a promising candidate as photoanode for solar-driven water splitting, with a theoretically predicted maximum solar-to-hydrogen conversion efficiency of ∼16%. However, the interfacial charge transfer and recombination greatly limits its activity for photoelectrochemical water splitting. Carbon dots exhibit great potential in photoelectrochemical water splitting for solar to hydrogen conversion as photosensitisers and co-catalysts. Here we developed a novel carbon underlayer from low-cost and environmental-friendly carbon dots through a facile hydrothermal process, introduced between the fluorine-doped tin oxide conducting substrate and hematite photoanodes. This led to a remarkable enhancement in the photocurrent density. Owing to the triple functional role of carbon dots underlayer in improving the interfacial properties of FTO/hematite and providing carbon source for the overlayer as well as the change in the iron oxidation state, the bulk and interfacial charge transfer dynamics of hematite are significantly enhanced, and consequently led to a remarkable enhancement in the photocurrent density. The results revealed a substantial improvement in the charge transfer rate, yielding a charge transfer efficiency of up to 80% at 1.25 V vs. RHE. In addition, a significant enhancement in the lifetime of photogenerated electrons and an increased carrier density were observed for the hematite photoanodes modified with a carbon underlayer, confirming that the use of sustainable carbon nanomaterials is an effective strategy to boost the photoelectrochemical performance of semiconductors for energy conversion.
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Affiliation(s)
- Qian Guo
- School of Engineering and Materials Science, Queen Mary University of London, E1 4NS, London, UK.
| | - Hui Luo
- Department of Chemical Engineering, Imperial College London, SW7 2AZ, London, UK
| | - Jifang Zhang
- Tsinghua-Foxconn Nanoscience Research Center, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Qiushi Ruan
- Department of Chemical Engineering, University College London, Torrington Place, WC1E 7JE, London, UK
| | - Arun Prakash Periasamy
- School of Engineering and Materials Science, Queen Mary University of London, E1 4NS, London, UK.
| | - Yuanxing Fang
- State Key Laboratory of Photocatalysis on Energy and Environment College of Chemistry, Fuzhou University, Fuzhou 350116, P. R. China
| | - Zailai Xie
- State Key Laboratory of Photocatalysis on Energy and Environment College of Chemistry, Fuzhou University, Fuzhou 350116, P. R. China
| | - Xuanhua Li
- School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, P. R. China
| | - Xinchen Wang
- State Key Laboratory of Photocatalysis on Energy and Environment College of Chemistry, Fuzhou University, Fuzhou 350116, P. R. China
| | - Junwang Tang
- Department of Chemical Engineering, University College London, Torrington Place, WC1E 7JE, London, UK
| | - Joe Briscoe
- School of Engineering and Materials Science, Queen Mary University of London, E1 4NS, London, UK.
| | - Magdalena Titirici
- Department of Chemical Engineering, Imperial College London, SW7 2AZ, London, UK
| | - Ana Belen Jorge
- School of Engineering and Materials Science, Queen Mary University of London, E1 4NS, London, UK.
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14
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Zhang H, Li D, Byun WJ, Wang X, Shin TJ, Jeong HY, Han H, Li C, Lee JS. Gradient tantalum-doped hematite homojunction photoanode improves both photocurrents and turn-on voltage for solar water splitting. Nat Commun 2020; 11:4622. [PMID: 32934221 PMCID: PMC7493915 DOI: 10.1038/s41467-020-18484-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/20/2020] [Indexed: 01/17/2023] Open
Abstract
Hematite has a great potential as a photoanode for photoelectrochemical (PEC) water splitting by converting solar energy into hydrogen fuels, but the solar-to-hydrogen conversion efficiency of state-of-the-art hematite photoelectrodes are still far below the values required for practical hydrogen production. Here, we report a core-shell formation of gradient tantalum-doped hematite homojunction nanorods by combination of hydrothermal regrowth strategy and hybrid microwave annealing, which enhances the photocurrent density and reduces the turn-on voltage simultaneously. The unusual bi-functional effects originate from the passivation of the surface states and intrinsic built-in electric field by the homojunction formation. The additional driving force provided by the field can effectively suppress charge–carrier recombination both in the bulk and on the surface of hematite, especially at lower potentials. Moreover, the synthesized homojunction shows a remarkable synergy with NiFe(OH)x cocatalyst with significant additional improvements of photocurrent density and cathodic shift of turn-on voltage. The work has nicely demonstrated multiple collaborative strategies of gradient doping, homojunction formation, and cocatalyst modification, and the concept could shed light on designing and constructing the efficient nanostructures of semiconductor photoelectrodes in the field of solar energy conversion. Solar-to-fuel conversion represents a renewable means to harvest sunlight, but the most efficient materials are often expensive or rare. Here, authors demonstrate gradient tantalum-doped hematite homojunctions as a method to improve photoelectrochemical water splitting performances.
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Affiliation(s)
- Hemin Zhang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Dongfeng Li
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Zhongshan Road 457, 116023, Dalian, China
| | - Woo Jin Byun
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Xiuli Wang
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Zhongshan Road 457, 116023, Dalian, China.
| | - Tae Joo Shin
- UNIST Central Research Facilities, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST, Ulsan, 44919, Republic of Korea
| | - Hu Young Jeong
- UNIST Central Research Facilities, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST, Ulsan, 44919, Republic of Korea.
| | - Hongxian Han
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Zhongshan Road 457, 116023, Dalian, China
| | - Can Li
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Zhongshan Road 457, 116023, Dalian, China
| | - Jae Sung Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan, 44919, Republic of Korea.
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15
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Arunachalam M, Ahn KS, Kang SH. Visible-light responsive BiNbO 4 nanosheet photoanodes for stable and efficient solar-driven water oxidation. Phys Chem Chem Phys 2020; 22:14042-14051. [PMID: 32567611 DOI: 10.1039/d0cp02071k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, we report bismuth niobate (BiNbO4), which is regarded as an emerging photoanode material for sustainable photoelectrochemical (PEC) solar energy conversion. BiNbO4 possesses a direct bandgap (Eg) of ∼2.6 eV, and shows an appropriate band alignment for the water oxidation/reduction reaction. In this study, a simple sol-gel route followed by a spin coating method was applied to develop BiNbO4 nanosheets under the optimum annealing conditions. It is known that the annealing temperatures of 500 and 550 °C influence the crystallinity and PEC properties of BiNbO4 films. In particular, the 550 °C annealed film exhibited sharply improved crystalline properties, and rapidly enhanced PEC performance, which were accompanied by a photocurrent density of 0.45 mA cm-2 at 1.23 V vs. the reversible hydrogen electrode (RHE) (briefly abbreviated as 1.23 VRHE) in a strong alkaline solution of 1 M NaOH, compared with 0.26 mA cm-2 at 1.23 VRHE of the 500 °C annealed film. This may be attributed to the main increase of the crystallinity, as well as the improvement of the electronic properties. In addition, the BiNbO4 (550 °C) film showed an incident photon-to-current efficiency of 20% at 425 nm, and produced a stable photoresponse under light illumination in a strong alkaline solution over 5 h, compared with a BiVO4 electrode.
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Affiliation(s)
- Maheswari Arunachalam
- Department of Chemistry, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Kwang-Soon Ahn
- School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea
| | - Soon Hyung Kang
- Department of Chemistry Education and Optoelectronic Convergence Research Center, Chonnam National University, Gwangju 500-757, Republic of Korea.
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Bedin KC, Muche DNF, Melo MA, Freitas ALM, Gonçalves RV, Souza FL. Role of Cocatalysts on Hematite Photoanodes in Photoelectrocatalytic Water Splitting: Challenges and Future Perspectives. ChemCatChem 2020. [DOI: 10.1002/cctc.202000143] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Karen C. Bedin
- Laboratory of Alternative Energy and Nanomaterials – LEANFederal University of ABC (UFABC) Avenida dos Estados 5001 09210-580 Santo André, SP Brazil
| | - Dereck N. F. Muche
- Laboratory of Alternative Energy and Nanomaterials – LEANFederal University of ABC (UFABC) Avenida dos Estados 5001 09210-580 Santo André, SP Brazil
| | - Mauricio A. Melo
- São Carlos Institute of Physics – IFSCUniversity of São Paulo (USP) Avenida Trabalhador São Carlense 400 PO Box 369 13560-970 São Carlos, SP Brazil
| | - Andre L. M. Freitas
- Laboratory of Alternative Energy and Nanomaterials – LEANFederal University of ABC (UFABC) Avenida dos Estados 5001 09210-580 Santo André, SP Brazil
| | - Renato V. Gonçalves
- São Carlos Institute of Physics – IFSCUniversity of São Paulo (USP) Avenida Trabalhador São Carlense 400 PO Box 369 13560-970 São Carlos, SP Brazil
| | - Flavio L. Souza
- Laboratory of Alternative Energy and Nanomaterials – LEANFederal University of ABC (UFABC) Avenida dos Estados 5001 09210-580 Santo André, SP Brazil
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17
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Yang Q, Du J, Li J, Wu Y, Zhou Y, Yang Y, Yang D, He H. Thermodynamic and Kinetic Influence of Oxygen Vacancies on the Solar Water Oxidation Reaction of α-Fe 2O 3 Photoanodes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:11625-11634. [PMID: 32073812 DOI: 10.1021/acsami.9b21622] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To reveal the role of oxygen vacancies in the solar water oxidation of α-Fe2O3 photoanodes, the kinetic and thermodynamic properties that are closely related to the water oxidation reaction of the α-Fe2O3 photoanode containing oxygen vacancies were investigated. Compared with the pristine α-Fe2O3 photoanode, the presence of surface oxygen vacancies can improve the water oxidation activity and stability of the α-Fe2O3 photoanode simultaneously, but the bulk oxygen vacancies have a negative effect on the water oxidation performance of the α-Fe2O3 photoanode. In thermodynamics, our investigations revealed that the presence of surface oxygen vacancies narrows the space charge region width of the α-Fe2O3 photoanode, which could boost the charge separation and transfer efficiency of the α-Fe2O3 photoanode during water oxidation. Because the surface property and hydrophilicity of α-Fe2O3 are modified owing to the presence of surface oxygen vacancies, the water oxidation kinetics of the α-Fe2O3 photoanode with surface oxygen vacancies is obviously boosted. Our findings in the present work provide comprehensive understanding of the thermodynamic and kinetic differences for α-Fe2O3 photoanodes with and without oxygen vacancies for solar water oxidation.
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Affiliation(s)
- Qian Yang
- State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
| | - Jinyan Du
- State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
| | - Jie Li
- State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
| | - Yuting Wu
- State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
| | - Yong Zhou
- Ecomaterials and Renewable Energy Research Center, School of Physics, Nanjing University, Nanjing 211102, China
| | - Yang Yang
- College of Chemistry and Chemical Engineering, Shannxi University of Science & Technology, Xi'an 710021, China
| | - Dingming Yang
- State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
| | - Huichao He
- State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
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18
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Long X, Wang C, Wei S, Wang T, Jin J, Ma J. Layered Double Hydroxide onto Perovskite Oxide-Decorated ZnO Nanorods for Modulation of Carrier Transfer Behavior in Photoelectrochemical Water Oxidation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:2452-2459. [PMID: 31845790 DOI: 10.1021/acsami.9b17965] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Despite the fact that perovskite oxides with high photoelectrochemical (PEC) stability have gained widespread concern in the field of photo(electro)catalytic water splitting, the potential as a photoelectrode has not yet fully exploited. Herein, perovskite oxide-decorated ZnO nanorod photoanode improves the vital issue that photoproduced electron-hole pairs are apt to be quenched, in which type II band alignment between perovskite oxide and ZnO plays a crucial role in extracting carriers. Further, coupling with layered double hydroxide (LDH) onto the heterostructure not only tunes surface injection behavior of charge carriers by facilitating the interface reaction dynamics but also suppresses ZnO self-corrosion for extended durability. As a result, the optimized CoAl-LDH/LaFeO3/ZnO nanorod photoanode yields a much enhancive effect for the PEC property in terms of photocurrent density (2.46 mA cm-2 at 1.23 V vs reversible hydrogen electrode under AM 1.5G), onset potential, and stability. This work signifies a feasible design to combine promising perovskite oxides with the traditional photoelectrode system for achieving efficient water splitting.
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Affiliation(s)
- Xuefeng Long
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , P. R. China
| | - Chenglong Wang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , P. R. China
| | - Shenqi Wei
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , P. R. China
| | - Tong Wang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , P. R. China
| | - Jun Jin
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , P. R. China
| | - Jiantai Ma
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , P. R. China
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19
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Gao B, Wang T, Li Y, Fan X, Gong H, Jiang C, Li P, Huang X, He J. Promoting hole transfer for photoelectrochemical water oxidation through a manganese cluster catalyst bioinspired by natural photosystem II. Chem Commun (Camb) 2020; 56:4244-4247. [DOI: 10.1039/d0cc00955e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A Mn4O4–cubane molecule bioinspired by the natural photosystem II was used as a co-catalyst in photoelectrochemical water oxidation.
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Affiliation(s)
- Bin Gao
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Tao Wang
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Yang Li
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Xiaoli Fan
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Hao Gong
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Cheng Jiang
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Peng Li
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Xianli Huang
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
| | - Jianping He
- College of Materials Science and Technology
- Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies
- Nanjing University of Aeronautics and Astronautics
- Nanjing
- P. R. China
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20
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Ma H, Kwon JA, Mahadik MA, Kim S, Lee HH, Choi SH, Chae WS, Lim DH, Jang JS. Effect of Sn-self diffusion via H 2 treatment on low temperature activation of hematite photoanodes. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00763c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A simple approach of lowering the activation temperature for hematite photoanode was developed. H2 treatment and air quenching allows Sn4+ diffusion from FTO to hematite which exhibited the photocurrent density of 1.17 mA cm−2 at 1.23 V vs. RHE.
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Affiliation(s)
- Haiqing Ma
- Division of Biotechnology
- Advanced Institute of Environmental and Bioscience
- College of Environmental and Bioresource Sciences
- Chonbuk National University
- Iksan 570-752
| | - Jeong An Kwon
- Department of Environmental Engineering
- Chungbuk National University
- Cheongju
- Republic of Korea
| | - Mahadeo A. Mahadik
- Division of Biotechnology
- Advanced Institute of Environmental and Bioscience
- College of Environmental and Bioresource Sciences
- Chonbuk National University
- Iksan 570-752
| | - Sarang Kim
- Division of Biotechnology
- Advanced Institute of Environmental and Bioscience
- College of Environmental and Bioresource Sciences
- Chonbuk National University
- Iksan 570-752
| | - Hyun Hwi Lee
- Pohang Accelerator Laboratory (PAL)
- Pohang University of Science and Technology (POSTECH)
- Pohang 37673
- Republic of Korea
| | - Sun Hee Choi
- Pohang Accelerator Laboratory (PAL)
- Pohang University of Science and Technology (POSTECH)
- Pohang 37673
- Republic of Korea
| | - Weon-Sik Chae
- Korea Basic Science Institute, Daegu Center
- Daegu 41566
- Republic of Korea
| | - Dong-Hee Lim
- Department of Environmental Engineering
- Chungbuk National University
- Cheongju
- Republic of Korea
| | - Jum Suk Jang
- Division of Biotechnology
- Advanced Institute of Environmental and Bioscience
- College of Environmental and Bioresource Sciences
- Chonbuk National University
- Iksan 570-752
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21
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Zhang H, Park JH, Byun WJ, Song MH, Lee JS. Activating the surface and bulk of hematite photoanodes to improve solar water splitting. Chem Sci 2019; 10:10436-10444. [PMID: 32110336 PMCID: PMC6988740 DOI: 10.1039/c9sc04110a] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 09/30/2019] [Indexed: 11/21/2022] Open
Abstract
A simple electrochemical activation treatment is proposed to improve effectively the photoelectrochemical performance of Nb,Sn co-doped hematite nanorods. The activation process involves an initial thrice cathodic scanning (reduction) and a subsequent thrice anodic scanning (oxidation), which modifies both the surface and bulk properties of the Nb,Sn:Fe2O3 photoanode. First, it selectively removes the surface components to different extents endowing the hematite surface with fewer defects and richer Nb-O and Sn-O bonds and thus passivates the surface trap states. The surface passivation effect also enhances the photoelectrochemical stability of the photoanode. Finally, more Fe2+ ions or oxygen vacancies are generated in the bulk of hematite to enhance its conductivity. As a result, the photocurrent density is increased by 62.3% from 1.88 to 3.05 mA cm-2 at 1.23 VRHE, the photocurrent onset potential shifts cathodically by ∼70 mV, and photoelectrochemical stability improves remarkably relative to the pristine photoanode under simulated sunlight (100 mW cm-2).
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Affiliation(s)
- Hemin Zhang
- School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Ulsan 44919 , Republic of Korea .
| | - Jong Hyun Park
- Perovtronics Research Center , Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50 , Ulsan , 44919 , Republic of Korea
| | - Woo Jin Byun
- School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Ulsan 44919 , Republic of Korea .
| | - Myoung Hoon Song
- Perovtronics Research Center , Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50 , Ulsan , 44919 , Republic of Korea
| | - Jae Sung Lee
- School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Ulsan 44919 , Republic of Korea .
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Zhang H, Lee JS. Hybrid Microwave Annealing Synthesizes Highly Crystalline Nanostructures for (Photo)electrocatalytic Water Splitting. Acc Chem Res 2019; 52:3132-3142. [PMID: 31603645 DOI: 10.1021/acs.accounts.9b00353] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hydrogen is regarded as an ideal energy carrier for the hydrogen economy that could replace the current hydrocarbon economy in order to achieve global energy security and mitigate climate change. For this purpose, H2 has to be produced from renewable sources (e.g., solar and wind) without producing global-warming CO2. (Photo)electrolysis of water into H2 and O2 is one of the most promising technologies for the production of renewable H2, which requires (photo)electrocatalysts of high efficiency, chemical robustness, and scalability. An essential attribute required for high-efficiency (photo)electrodes is high crystallinity with few defects to facilitate charge transfer without recombination. To this end, fabrication of photoelectrodes is usually completed with high temperature thermal annealing in a furnace. However, conventional thermal annealing (CTA) always results in undesirable crystal sintering, which reduces the surface area, and damage to the transparent conducting oxide (TCO) substrate. An emerging alternative method, hybrid microwave annealing (HMA), offers the beneficial effect of the high-temperature annealing (crystallinity) while minimizing its negative effects of sintering and TCO damage, enabling the fabrication of efficient (photo)electrodes for water splitting. HMA combines direct microwave heating with additional heating from an effective microwave absorber (called a susceptor), thereby avoiding a nonuniform temperature distribution between the interior and exterior of the synthesized material. More importantly, an extremely high temperature of the entire sample can be reached in only a few minutes. Compared with CTA, HMA has several advantages in the preparation of (photo)electrodes: (i) formation of a high-purity phase; (ii) high crystallinity with fewer defects; (iii) preservation of the original nanostructure; (iv) less damage to the TCO substrate for photoelectrodes; (v) smaller nanocrystals and uniform dispersion of catalyst particles. Overall, HMA is a convenient, ultrafast, and energy-economical technology for the synthesis of efficient (photo)electrodes. In this Account, we discuss recent progress made in our laboratory on HMA for preparing photoanodes (Fe2O3, BiVO4, ZnFe2O4, and Fe2TiO5), photocathodes (Cu2O and CuFeO2), and a graphene-based electrocatalyst (MoS2/graphene composite), which exhibit distinctive behavior and efficient performance in (photo)electrocatalytic water splitting. In particular, we have advanced the HMA technique further to synthesize hematite-based photoanodes with core-shell heterojunction nanorods (Nb,Sn:Fe2O3@FeNbO4 and Ta,Sn:Fe2O3@FeTaO4) by solid-solid interface reaction, which simultaneously achieves multiple doping effects (Nb or Ta, Sn) to improve the photoelectrocatalysis of water splitting. Thus, this Account focuses on the synthetic aspects of HMA, which may offer new research opportunities for the synthesis of other metal oxide (photo)electrode materials and hybrid electrocatalysts in the fields of solar energy conversion and storage, secondary batteries, and H2 fuel production.
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Affiliation(s)
- Hemin Zhang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Jae Sung Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
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Wang L, Zhu J, Liu X. Oxygen-Vacancy-Dominated Cocatalyst/Hematite Interface for Boosting Solar Water Splitting. ACS APPLIED MATERIALS & INTERFACES 2019; 11:22272-22277. [PMID: 31244023 DOI: 10.1021/acsami.9b03789] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Surface suppression is one of critical issues for semiconductors in photoelectrochemical (PEC) water splitting. Deposition of oxygen evolution cocatalysts on photoanodes can improve the oxygen evolution rate, but still it has some limits in some cases. In this work, we propose a new and simple precipitation approach to transform the surface of hematite into iron phosphate (Fe-Pi). Further, Ar-plasma treatment on Fe-Pi/Fe2O3 introduces oxygen vacancies on the phosphorous and photoanode. A surface phosphate treatment accelerates the transfer of holes from the bulk to the surface. Besides, creating oxygen vacancy defects on Fe-Pi/Fe2O3 can significantly increase the reactivity of active sites, leading to the remarkable enhancement in oxygen evolution reaction activity and PEC performance. The resulting photoanode has a current density of 2.71 mA cm-2 at 1.23 VRHE and 3.5 mA cm-2 at 1.50 VRHE under simulated solar light condition. The reduced surface recombination by Fe-Pi layer and Ar-plasma treatment is confirmed by electrochemical analysis. These findings give a great potential of the use of a combination strategy for cocatalyst deposition and optimizing the performance of hematite.
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Affiliation(s)
- Lei Wang
- College of Chemistry and Chemical Engineering and Inner Mongolia Key Lab of Nanoscience and Nanotechnology , Inner Mongolia University , Hohhot 010021 , China
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates , Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou 730000 , China
- Key Laboratory of Materials Processing and Mold, Ministry of Education , Zhengzhou University , Zhengzhou 450002 , China
| | - Jie Zhu
- College of Chemistry and Chemical Engineering and Inner Mongolia Key Lab of Nanoscience and Nanotechnology , Inner Mongolia University , Hohhot 010021 , China
| | - Xianhu Liu
- Key Laboratory of Materials Processing and Mold, Ministry of Education , Zhengzhou University , Zhengzhou 450002 , China
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