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Mahadik MA, Anushkkaran P, Chae WS, Lee HH, Cho M, Jang JS. TiO 2 nanorod/nanotube interface reconstruction and synergistic role of oxygen vacancies and gold in H-Au-TiO 2 NR/NT for photoelectrochemical bacterial inactivation and water splitting. CHEMOSPHERE 2023; 341:139968. [PMID: 37643649 DOI: 10.1016/j.chemosphere.2023.139968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/14/2023] [Accepted: 08/24/2023] [Indexed: 08/31/2023]
Abstract
Photoelectrochemical (PEC) water splitting by semiconductor photoanodes is limited by sluggish water oxidation kinetics coupled with serious charge recombinations. In this paper, an effective strategy of TiO2 nanorod/nanotube nanostructured interface reconstruction, oxygen vacancies and surface modification were employed for stability and efficient charge transport in the photoanodes. Successive anodization and hydrothermal routes were adopted for the TiO2 NR/NT photoanodes interface reconstruction, followed by Au nanoparticles/clusters (Au NP) loading and hydrogen treatment. This resulted in H-Au-TiO2 NR/NT photoanodes. A three-dimensional structure of TiO2 NR on TiO2 NT/Ti foil nanotubes achieved the highest photocurrent density (1.42 mA cm-2 at 0.3 V vs. Ag/AgCl). The optimal oxygen vacancies and Au NP loading on TiO2 NR/NT exhibited 1.62 mA cm-2 photocurrent density at 0.3 V vs. Ag/AgCl in H-Au-TiO2 NR/NT photoelectrode, which is eight times higher than the TiO2 NT/Ti foil. TRPL analyses confirm the hydrogen treatments to TiO2 exhibited the emission lifetime (46 ns) in the H-Au-TiO2 NR/NT photoanodes due to newly formed lower Ti3+-related trapped electron states and Au NP. The optimum H-Au (4)-TiO2 NR/NT photoanodes achieved 95% photoelectrochemical (PEC) bacterial inactivation and effective PEC water splitting with (278 and 135.4) μmol of hydrogen and oxygen generation, respectively. In this study, oxygen vacancies combined with gold particles and interface reconstruction provide an innovative way to design effective photoelectrodes.
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Affiliation(s)
- Mahadeo A Mahadik
- Division of Biotechnology, Safety, Environment and Life Science Institute, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, 54596, Republic of Korea
| | - Periyasamy Anushkkaran
- Department of Integrative Environmental Biotechnology, Safety, Environment and Life Science Institute, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, 54596, Republic of Korea
| | - Weon-Sik Chae
- Daegu Center, Korea Basic Science Institute, Daegu, 41566, Republic of Korea
| | - Hyun Hwi Lee
- Pohang Accelerator Laboratory (PAL), Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Min Cho
- Division of Biotechnology, Safety, Environment and Life Science Institute, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, 54596, Republic of Korea.
| | - Jum Suk Jang
- Division of Biotechnology, Safety, Environment and Life Science Institute, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, 54596, Republic of Korea; Department of Integrative Environmental Biotechnology, Safety, Environment and Life Science Institute, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan, 54596, Republic of Korea.
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Yamada K, Suzuki H, Abe R, Saeki A. Complex Photoconductivity Reveals How the Nonstoichiometric Sr/Ti Affects the Charge Dynamics of a SrTiO 3 Photocatalyst. J Phys Chem Lett 2019; 10:1986-1991. [PMID: 30964685 DOI: 10.1021/acs.jpclett.9b00880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Strontium titanate (SrTiO3) is a perovskite that is important in water-splitting photocatalytic chemistry. Although excess Sr is known to improve the photocatalytic activity, its effect on charge dynamics remain largely unaddressed. Herein, we present a detailed analyses of gigahertz complex transient photoconductivity (Δσ) measured using time-resolved microwave conductivity (TRMC). We show that charge carrier trapping associated with the emergence of an anomalous positive imaginary part and the first-order rate constant of the normal positive real part of Δσ dramatically decreased with increasing Sr/Ti ratio. The second-order rate constant attributed to charge recombination simultaneously decreased, and these rate constants were well correlated with the improved hydrogen evolution rate of aqueous SrTiO3 suspensions with a Pt co-catalyst. These findings provide a fresh perspective on the stoichiometry-carrier dynamics relationship paramount for the optimization of composition-engineered photocatalysts and reveal the broad implications for mechanistic studies based on TRMC evaluation.
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Affiliation(s)
- Kento Yamada
- Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Hajime Suzuki
- Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Ryu Abe
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering , Kyoto University , Nishikyo-ku, Kyoto 615-8510 , Japan
| | - Akinori Saeki
- Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
- Precursory Research for Embryonic Science and Technology (PRESTO) , Japan Science and Technology Agency , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan
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Sheng X, Xu T, Feng X. Rational Design of Photoelectrodes with Rapid Charge Transport for Photoelectrochemical Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805132. [PMID: 30637813 DOI: 10.1002/adma.201805132] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 11/23/2018] [Indexed: 06/09/2023]
Abstract
Photoelectrode materials are the heart of photoelectrochemical (PEC) cells, which hold great promise to address global energy and environmental issues by converting solar energy into electricity or chemical fuels. In recent decades, significant research efforts have been devoted to the design and construction of photoelectrodes for the efficient generation and utilization of charge carriers to boost PEC performance. Herein, insights from a literature study on the relationship between the architecture and charge dynamics of photoelectrodes are presented. After briefly introducing the fundamental theories of charge dynamics in nanostructured photoelectrodes, the development of photoelectrode design in 1D polycrystalline nanotube arrays, 1D single-crystalline nanowire arrays, and hierarchical and mesoporous nanowire arrays is reviewed with a focus on the interplay between architecture and charge transport properties. For each design, commonly used synthetic approaches and the corresponding charge transport properties are discussed. Subsequently, the applications of these photoelectrodes in PEC systems are summarized. In conclusion, future challenges in the rational design of photoelectrode architecture are presented. The basic relationships between the architectures and charge dynamics of photoelectrode materials discussed here are expected to provide pertinent guidance and a reference for future advanced material design targeting improved light energy conversion systems.
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Affiliation(s)
- Xia Sheng
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. China
| | - Tao Xu
- Department of Chemistry and Biochemistry, Northern Illinois University, Dekalb, IL, 60115, USA
| | - Xinjian Feng
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. China
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Radiative and Non-Radiative Recombination Pathways in Mixed-Phase TiO2 Nanotubes for PEC Water-Splitting. Catalysts 2019. [DOI: 10.3390/catal9020204] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Anatase and rutile mixed-phase TiO2 with an ideal ratio has been proven to significantly enhance photoelectrochemical (PEC) activity in water-splitting applications due to suppressing the electron–hole recombination. However, the mechanism of this improvement has not been satisfactory described yet. The PEC water oxidation (oxygen evolution) at the interface of TiO2 photoanode and electrolyte solution is determined by the fraction of the photogenerated holes that reach the solution and it is defined as the hole transfer efficiency. The surface and bulk recombination processes in semiconductor photoanodes majorly influence the hole transfer efficiency. In this work, we study the hole transfer process involved in mixed-phase TiO2 nanotube arrays/solution junction using intensity-modulated photocurrent and photovoltage spectroscopy (IMPS and IMVS); then, we correlate the obtained hole transfer rate constants to (photo)electrochemical impedance spectroscopy (PEIS) measurements. The results suggest that the enhanced performance of the TiO2 mixed-phase is due to the improved hole transfer rate across the TiO2/liquid interface as well as to the decrease in the surface trap recombination of the holes.
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