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13. Inooh-Mediated Intergrown Heterojunctions for Enhanced Photocatalytic Performance: Assembly and Interfacial Charge Carrier Transferring

Author

Nekouei, Farzin, primary, Wen, Xiaoming, additional, Zheng, Zhong, additional, Sun, Qingbo, additional, Lu, Teng, additional, Orton, Henry, additional, Kremer, Felipe, additional, Nekouei, Shahram, additional, Yuan, Tongwei, additional, Abdelkader, Elwy H., additional, Liu, Borui, additional, Tricoli, Antonio, additional, Otting, Gottfried, additional, Liu, Zongwei, additional, Frankcombe, Terry, additional, and Liu, Yun, additional

Published
2022
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17. Hole-Pinned Defect Clusters for a Large Dielectric Constant up to GHz in Zinc and Niobium Codoped Rutile SnO2

Author

Jiang, Mengqi, primary, Hu, Wanbiao, additional, Jacob, Lilit, additional, Sun, Qingbo, additional, Cox, Nicholas, additional, Kim, Doukyun, additional, Tian, Ye, additional, Zhao, Luyang, additional, Liu, Yang, additional, Jin, Li, additional, Xu, Zhuo, additional, Liu, Peng, additional, Zhao, Gang, additional, Wang, Jian, additional, Svirskas, Šaru̅nas, additional, Banys, Ju̅ras, additional, Park, Chul-hong, additional, Frankcombe, Terry J., additional, Wei, Xiaoyong, additional, and Liu, Yun, additional

Published
2021
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21. High performance bulk photovoltaics in narrow-bandgap centrosymmetric ultrathin films

Author

Mai, Haoxin, Lu, Teng, Sun, Qingbo, Elliman, Robert, Kremer, Felipe, Duong, The, Catchpole, Kylie, Li, Qian, Yi, Zhiguo, Frankcombe, Terry J., Liu, Yun, Mai, Haoxin, Lu, Teng, Sun, Qingbo, Elliman, Robert, Kremer, Felipe, Duong, The, Catchpole, Kylie, Li, Qian, Yi, Zhiguo, Frankcombe, Terry J., and Liu, Yun

Abstract

In conventional bulk photovoltaics (BPVs), it is difficult to acquire both intensive photocurrent and large photovoltage output, which greatly limits the practical application. Here, we report a new strategy that can significantly increase photocurrent by five orders of magnitude whilst retaining the nature of high photovoltage of BPVs by introducing the local-chemistry-induced polar nanoregions (PNRs) into narrow-bandgap centrosymmetric ultrathin films. It is believed that these PNRs distribute randomly in non-ferroelectric insulator matrix and contribute to ferroelectric-like polarization when the sample thickness is comparable to the PNRs sizes. This allows to establish an internal field to effectively separate photogenerated electron–hole pairs even in centrosymmetric materials with narrow bandgap, and thus the power conversion efficiency (PCE) will increase significantly. BiVO4 (BVO) hereof is exemplified. Through intergrowing polar Bi4V2O11 nanoregions into the ultra-thin narrow bandgap BVO film, the PCE increases 1000 times compared with that of the BVO ceramic without taking advantage of the PNRs. This new strategy of producing high PV output in narrow-bandgap semiconductor thin films therefore will extend the candidate pool of bulk PV materials beyond traditional ferroelectricity, providing a pathway for practical application of bulk PV effect. Additionally, the combination of ferroelectric-like feature with a narrow bandgap in one material may create new optoelectronic functions.

Published
2020

25. Collective nonlinear electric polarization: Via defect-driven local symmetry breaking

Author

Dong, Wen, Cortie, David L, Lu, Teng, Sun, Qingbo, Narayanan, Narendirakumar, Hu, Wanbiao, Jacob, Lilit, Li, Qian, Yu, Dehong, Chen, Hua, Chen, Aiping, Wei, Xiaoyong, Wang, Genmiao, Humphrey, Mark G, Frankcombe, Terry J, Liu, Yun, Dong, Wen, Cortie, David L, Lu, Teng, Sun, Qingbo, Narayanan, Narendirakumar, Hu, Wanbiao, Jacob, Lilit, Li, Qian, Yu, Dehong, Chen, Hua, Chen, Aiping, Wei, Xiaoyong, Wang, Genmiao, Humphrey, Mark G, Frankcombe, Terry J, and Liu, Yun

Abstract

In this work, we report the defect-mediated, abnormal non-linear polarization behavior observed in centrosymmetric rutile TiO2 where less than 1 at% of sterically mismatched Mg2+ ions are introduced to create ferroelectric-like polarization hysteresis loops. It is found that the defect cluster produces a dipole moment exceeding 6 Debye, with a rotatable component. Such a polarization is further enhanced by the displacement of neighboring Ti4+ ions. The coupling between such defect-driven symmetry-breaking regions generates a collective nonlinear electrical polarization state that persists to high temperatures. More importantly, an observation of abnormal bias shift of polarization hysteresis suggests an antiparallel alignment of certain dipoles frozen relative to the external poling electric field, which is associated with oxygen vacancy hopping. This result challenges the long-standing notion of parallel alignment of dipoles with the external electric field in ferroelectrics. This work also reveals an unexpected new form of non-linear dielectric polarization (non-ferroelectricity) in solid-state materials.

Published
2019

26. Highly Efficient Visible Light Catalysts Driven by Ti3+‐VO‐2Ti4+‐N3− Defect Clusters

Author

Sun, Qingbo, Zhang, Shaoyang, Cortie, David L, Langley, Julien, Cox, Nicholas, Frankcombe, Terry J, Gao, Jie, Chen, Hua, Withers, Ray L, Kremer, Felipe, Yu, Dehong, Brink, Frank, Shi, Wensheng, Liu, Yun, Sun, Qingbo, Zhang, Shaoyang, Cortie, David L, Langley, Julien, Cox, Nicholas, Frankcombe, Terry J, Gao, Jie, Chen, Hua, Withers, Ray L, Kremer, Felipe, Yu, Dehong, Brink, Frank, Shi, Wensheng, and Liu, Yun

Abstract

Local defect structures play significant roles on material properties, but they are seriously neglected in the design, synthesis, and development of highly efficient TiO2‐based visible light catalysts (VLCs). Here, we take anatase TiO2 nanocrystals that contain (Ti3+, N3−) ions and have the complicated chemical formula of ( )( ) as an example, and point out that the formation of Ti3+‐VO‐2Ti4+‐N3− local defect clusters is a key missing step for significantly enhancing VLC properties of host TiO2 nanocrystals. Experimental and theoretical investigations also demonstrate the emergent behaviors of these intentionally introduced defect clusters for developing highly efficient VLCs. This research thus not only provides highly efficient visible light catalysts for various practical applications but also addresses the significance of local defect structures on modifying material properties.

Published
2019

28. Defect engineering for creating and enhancing bulk photovoltaic effect in centrosymmetric materials.

Author

Mai, Haoxin, Lu, Teng, Sun, Qingbo, Langley, Julien, Cox, Nicholas, Kremer, Felipe, Duong, The, Catchpole, Kylie, Chen, Hua, Yi, Zhiguo, Frankcombe, Terry J., and Liu, Yun

Abstract

The bulk photovoltaic (BPV) effect of conventional ferroelectric (FE) materials has sparked a great deal of interest due to anomalous above-bandgap photovoltage. However, large bandgaps and weak photocurrents remain longstanding challenges for FE PV materials in practical applications. To address these issues, we propose a new defect-engineering strategy and demonstrate it on a narrow bandgap centrosymmetric material, BiNbO4 (BNO): the BPV effect is introduced into BNO by tuning the defect amounts, then a defect-modified homojunction structure is constructed to enhance the BPV effect. This defect engineering strategy enables synergetic effects, e.g., enhanced light absorption, FE-like depolarization field and interfacial polarization. This homojunction structure results in two-fold promotion of photovoltage and ten-fold promotion of photocurrent, compared to the defect-modified BNO sample. We believe this new strategy will break through limitations in traditional material design and pave a novel route to future multifunctional materials, especially high performance BPV materials. [ABSTRACT FROM AUTHOR]

Published
2021
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30. Peptide PD29 treats bleomycin-induced pulmonary fibrosis by inhibiting the TGF-β/smad signaling pathway

Author

Sun, Qingbo, primary, Hu, Jialiang, additional, Yu, Pengcheng, additional, Zhu, Zhaohao, additional, Yu, Ruihe, additional, Ge, Chuang, additional, Li, Chencheng, additional, Wu, Guiyue, additional, Lin, Bingjing, additional, Liu, Guangpan, additional, Liu, Meng, additional, Bian, Huan, additional, Xu, Hanmei, additional, and Jia, Shaochang, additional

Published
2019
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31. Collective nonlinear electric polarization via defect-driven local symmetry breaking

Author

Dong, Wen, primary, Cortie, David, additional, Lu, Teng, additional, Sun, Qingbo, additional, Narayanan, Narendirakumar, additional, Hu, Wanbiao, additional, Jacob, Lilit, additional, Li, Qian, additional, Yu, Dehong, additional, Chen, Hua, additional, Chen, Aiping, additional, Wei, Xiaoyong, additional, Wang, Genmiao, additional, Humphrey, Mark G., additional, Frankcombe, Terry J., additional, and Liu, Yun, additional

Published
2019
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33. Photovoltaic Effect of a Ferroelectric-Luminescent Heterostructure under Infrared Light Illumination

Author

Mai, Haoxin, Lu, Teng, Li, Qian, Sun, Qingbo, Vu, Khu, Chen, Hua, Wang, Genmiao, Humphrey, Mark, Kremer, Felipe, Li, Li (Lily), Withers, Raymond, Liu, Yun, Mai, Haoxin, Lu, Teng, Li, Qian, Sun, Qingbo, Vu, Khu, Chen, Hua, Wang, Genmiao, Humphrey, Mark, Kremer, Felipe, Li, Li (Lily), Withers, Raymond, and Liu, Yun

Abstract

In this report, a ferroelectric-luminescent heterostructure is designed to convert infrared light into electric power. We use BiFeO3 (BFO) as the ferroelectric layer and Y2O3:Yb,Tm (YOT) as the upconversion layer. Different from conventional ferroelectric materials, this heterostructure exhibits switchable and stable photovoltaic effects under 980 nm illumination, whose energy is much lower than the band gap of BFO. The energy transfer mechanism in this heterostructure is therefore studied carefully. It is found that a highly efficient nonradiative energy transfer process from YOT to BFO plays a critical role in achieving the below-band-gap photon-excited photovoltaic effects in this heterostructure. Our results also indicate that by introducing asymmetric electrodes, both the photovoltage and photocurrent are further enhanced when the built-in field and the depolarization field are aligned. The construction of ferroelectric-luminescent heterostructure is consequently proposed as a promising route to enhance the photovoltaic effects of ferroelectric materials by extending the absorption of the solar spectrum.

Published
2018

34. Heterogeneous photocatalytic decomposition of per- and poly-fluoroalkyl substances: A review.

Author

Sun, Qingbo, Zhao, Chunyan, Frankcombe, Terry J., Liu, Hong, and Liu, Yun

Subjects
*PHOTOCATALYSIS, *POLLUTANTS, *CHEMICAL decomposition, *MOLECULAR structure, *CHEMICAL reactions, *INDUSTRIAL capacity
Abstract

Per- and poly-fluoroalkyl substances (PFASs) as emergent contaminants are generating serious environmental and health issues. An imminent task is thus to develop effective technologies to completely remove and ideally decompose PFASs through physical and/or chemical routes. Heterogeneous photocatalysis, which directly utilizes sunlight to drive the chemical decomposition of many organic compounds, is a promising solution to remediating PFASs-contaminated environment. In this review, the current progress of heterogeneous photocatalytic technology for decomposing PFASs is systematically summarized. The significance of environmental factors during heterogeneous photocatalysis is discussed from three aspects including anaerobic vs aerobic, acidic vs alkaline, and light use vs light loss. The associated reaction mechanisms and reaction routes are analyzed based on the stepwise change of PFASs molecular structures. Some further issues regarding PFASs heterogeneous photocatalysis are briefly pointed out along with the potential industrial applications of this technology. Heterogeneous photocatalysis is a promising solution to remediating environmental contaminants since it directly uses sunlight to drive the associated chemical reactions. Here, we review the current progress of heterogeneous photocatalytic technology for decomposing per- and poly-fluoroalkyl substances. Common issues and future development directions in this field are suggested. [ABSTRACT FROM AUTHOR]

Published
2020
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35. Highly Efficient Visible Light Catalysts Driven by Ti3+ -VO -2Ti4+ -N3− Defect Clusters

Author

Sun, Qingbo, primary, Zhang, Shaoyang, additional, Cortie, David, additional, Langley, Julien, additional, Cox, Nicholas, additional, Frankcombe, Terry J., additional, Gao, Jie, additional, Chen, Hua, additional, Withers, Ray L., additional, Kremer, Felipe, additional, Yu, Dehong, additional, Brink, Frank, additional, Shi, Wensheng, additional, and Liu, Yun, additional

Published
2018
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39. Controlling magnetic properties of Fe3+ doped indium oxide nanocubes by atmospheric annealing method.

Author

Sun, Qingbo, Zeng, Yuping, and Jiang, Dongliang

Subjects
*MAGNETIC properties, *FERROMAGNETIC materials, *ANNEALING of metals, *INDIUM spectra, *X-ray diffraction, *TRANSMISSION electron microscopy
Abstract

Fe3+ doped In2O3 nanocubes with different doped concentrations (from 5 at. % to 15 at. %) were prepared by direct solvothermal method and 10 at. % doped samples were then annealed under atmospheric conditions to investigate effects of annealing temperatures on their magnetic properties. The magnetic transitions from paramagnetic to ferromagnetic and again to paramagnetic occurred with increments of annealing temperatures, since the oxygen vacancies affected exchanges of two neighboring Fe3+ ions. Moreover, their magnetic properties were further demonstrated to be intrinsic by X-ray diffraction, high-resolution transmission electron microscopy, and X-ray energy dispersive spectrometry. [ABSTRACT FROM AUTHOR]

Published
2011
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40. The Formation of Defect-Pairs for Highly Efficient Visible-Light Catalysts

Author

Sun, Qingbo, Cortie, David, Zhang, Shaoyang, Frankcombe, Terry J, She, Guangwei, Gao, Jie, Sheppard, Leigh R, Hu, Wanbiao, Chen, Hua, Zhuo, Shangjun, Chen, Dehong, Withers, Ray L, McIntyre, Garry, Yu, Dehong, Shi, Wensheng, Liu, Yun, Sun, Qingbo, Cortie, David, Zhang, Shaoyang, Frankcombe, Terry J, She, Guangwei, Gao, Jie, Sheppard, Leigh R, Hu, Wanbiao, Chen, Hua, Zhuo, Shangjun, Chen, Dehong, Withers, Ray L, McIntyre, Garry, Yu, Dehong, Shi, Wensheng, and Liu, Yun

Abstract

Highly efficient visible-light catalysts are achieved through forming defect-pairs in TiO2 nanocrystals. This study therefore proposes that fine-tuning the chemical scheme consisting of charge-compensated defect-pairs in balanced concentrations is a key missing step for realizing outstanding photocatalytic performance. This research benefits photocatalytic applications and also provides new insight into the significance of defect chemistry for functionalizing materials.

Published
2017

44. The Formation of Defect‐Pairs for Highly Efficient Visible‐Light Catalysts

Author

Sun, Qingbo, primary, Cortie, David, additional, Zhang, Shaoyang, additional, Frankcombe, Terry J., additional, She, Guangwei, additional, Gao, Jie, additional, Sheppard, Leigh R., additional, Hu, Wanbiao, additional, Chen, Hua, additional, Zhuo, Shangjun, additional, Chen, Dehong, additional, Withers, Ray L., additional, McIntyre, Garry, additional, Yu, Dehong, additional, Shi, Wensheng, additional, and Liu, Yun, additional

Published
2017
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45. Chemical Synthesis and High-Pressure Reaction of Nb5+Monodoped Rutile TiO2Nanocrystals

Author

Sun, Qingbo, Huston, Larissa Q., Tang, Chunguang, Wei, Lingling, Sheppard, Leigh R., Chen, Hua, Frankcombe, Terry J., Bradby, Jodie E., and Liu, Yun

Abstract

Identifying the doping effects of extrinsic ions both during chemical reactions and in resultant products is important to deeply understand the associated material properties and to develop novel materials for practical applications. Here, we experimentally demonstrate the significant inhibitor effect of Nb5+dopants on the formation of rutile TiO2nanocrystals through dopant concentration-modified solvothermal reaction processes. A lower Nb5+doping level (≤9.09 atom %) is found to be more beneficial for the nucleation and growth of rutile Ti1 – 2x4+Tix3+Nbx5+O2nanocrystals while a higher one (>9.09 at.%) leads to the preferable formation of the anatase phase. At a pressure range of up to 30 GPa, the synthesized Nb5+monodoped rutile TiO2nanocrystals almost possess an equal slope in their respective plot of the pressure-dependent Raman frequency shifts and a similar structural transformation from rutile to baddeleyite-like (pressurization) and then to an α-PbO2-like phase (depressurization). They thus present a dopant concentration-independent high-pressure reaction behavior due to a small change in their average and local defect structures evidenced by the bond valence sum analysis and density functional theory calculations. This work not only emphasizes the key roles of dopants in material synthesis but also broadens insights into the intrinsic correlations between material properties and their specific local defects.

Published
2020
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46. Highly Efficient Visible Light Catalysts Driven by Ti3+‐VO‐2Ti4+‐N3− Defect Clusters.

Author

Sun, Qingbo, Langley, Julien, Cox, Nicholas, Withers, Ray L., Liu, Yun, Cortie, David, Zhang, Shaoyang, Shi, Wensheng, Yu, Dehong, Frankcombe, Terry J., Gao, Jie, Chen, Hua, Kremer, Felipe, and Brink, Frank

Subjects
ENERGY shortages, ELECTRONIC band structure, PHOTOEXCITATION, CHARGE carriers, CHEMICAL synthesis, HYDROGENATION
Abstract

Local defect structures play significant roles on material properties, but they are seriously neglected in the design, synthesis, and development of highly efficient TiO2‐based visible light catalysts (VLCs). Here, we take anatase TiO2 nanocrystals that contain (Ti3+, N3−) ions and have the complicated chemical formula of (Ti1-x4+Tix3+)(O2-y-z2-Ny3- □z) as an example, and point out that the formation of Ti3+‐VO‐2Ti4+‐N3− local defect clusters is a key missing step for significantly enhancing VLC properties of host TiO2 nanocrystals. Experimental and theoretical investigations also demonstrate the emergent behaviors of these intentionally introduced defect clusters for developing highly efficient VLCs. This research thus not only provides highly efficient visible light catalysts for various practical applications but also addresses the significance of local defect structures on modifying material properties. Defect‐clusters‐driven: Local defect structure could determine or create material properties since it could change a local chemical environment and subsequently mediate the electronic state density of materials. Here, we demonstrate that the deliberate design and formation of Ti3+‐VO‐2Ti4+‐N3− defect clusters in TiO2 anatase nanocrystals would drive the highly efficient visible light catalytic decomposition of organic contaminates. This research thus not only presents a defect‐engineering route to design/develop highly efficient visible light catalysts but also highlights the significance of local defect structures on modifying material properties. [ABSTRACT FROM AUTHOR]

Published
2019
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47. Collective nonlinear electric polarization viadefect-driven local symmetry breakingElectronic supplementary information (ESI) available. See DOI: 10.1039/c9mh00516a

Author

Dong, Wen, Cortie, David, Lu, Teng, Sun, Qingbo, Narayanan, Narendirakumar, Hu, Wanbiao, Jacob, Lilit, Li, Qian, Yu, Dehong, Chen, Hua, Chen, Aiping, Wei, Xiaoyong, Wang, Genmiao, Humphrey, Mark G., Frankcombe, Terry J., and Liu, Yun

Abstract

In this work, we report the defect-mediated, abnormal non-linear polarization behavior observed in centrosymmetric rutile TiO2where less than 1 at% of sterically mismatched Mg2+ions are introduced to create ferroelectric-like polarization hysteresis loops. It is found that the defect cluster produces a dipole moment exceeding 6 Debye, with a rotatable component. Such a polarization is further enhanced by the displacement of neighboring Ti4+ions. The coupling between such defect-driven symmetry-breaking regions generates a collective nonlinear electrical polarization state that persists to high temperatures. More importantly, an observation of abnormal bias shift of polarization hysteresis suggests an antiparallel alignment of certain dipoles frozen relative to the external poling electric field, which is associated with oxygen vacancy hopping. This result challenges the long-standing notion of parallel alignment of dipoles with the external electric field in ferroelectrics. This work also reveals an unexpected new form of non-linear dielectric polarization (non-ferroelectricity) in solid-state materials.

Published
2019
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