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Yoshida A, Pirabul K, Fujii S, Pan ZZ, Yoshii T, Ito M, Izawa K, Minegishi Y, Noguchi Y, Hiyoshi N, Takeda K, Hasegawa Y, Itoh T, Nishihara H. Contamination-Free Reference Electrode Using Prussian Blue for Small Oxygen Sensors. ACS APPLIED MATERIALS & INTERFACES 2024; 16:50115-50124. [PMID: 39161048 DOI: 10.1021/acsami.4c05103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
In recent years, significant attention has been directed toward advancing compact, point-of-care testing (POCT) devices to better deliver patient care and alleviate the burden on the medical care system. Common POCTs, such as blood oxygen sensors, leverage electrochemical sensing in their design. However, conventional electrochemical devices typically use Ag/AgCl reference electrodes, which are likely to release trace amounts of silver ions that contaminate the working electrode, causing rapid deterioration of the devices. This study proposes an effective reference electrode using graphene-coated porous silica spheres (G/PSS) with embedded Prussian blue (PB), denoted PB/G/PSS, designed specifically for small oxygen sensors. PB is a redox species that is an improvement over Ag/AgCl since it is significantly less water-soluble than AgCl. Since PB is an insulator, we dispersed PB in G/PSS, well-conductive mesoporous matrices, to ensure contact between PB clusters and the electrolytes. Moreover, the monodispersed, spherically shaped PB/G/PSS is an advantageous medium for fabricating POCT devices by screen printing. In this study, the open-circuit potential of the PB/G/PSS electrode remained stable within 30 mV for 31 days. The small oxygen sensor assembled through screen printing using PB/G/PSS demonstrated stable operation for several days or more. In contrast, a similar sensor with Ag/AgCl reference electrode rapidly deteriorated within a day. This PB/G/PSS reference electrode with improved stability is expected to be an excellent alternative to the Ag/AgCl system for small electrochemical-based POCT devices.
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Affiliation(s)
- Akiko Yoshida
- Techno Medica Co., Ltd., Yokohama, Kanagawa 224-0041, Japan
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Kritin Pirabul
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Shunsuke Fujii
- Department of Pediatric Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Zheng-Ze Pan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Takeharu Yoshii
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Mutsuhiro Ito
- Fuji Silysia Chemical Ltd., Kasugai, Aichi 487-0013, Japan
| | - Kenichi Izawa
- Fuji Silysia Chemical Ltd., Kasugai, Aichi 487-0013, Japan
| | - Yuka Minegishi
- Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Sendai, Miyagi 983-855, Japan
| | | | - Norihito Hiyoshi
- Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Sendai, Miyagi 983-855, Japan
| | - Kota Takeda
- Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Sendai, Miyagi 983-855, Japan
| | - Yasuhisa Hasegawa
- Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Sendai, Miyagi 983-855, Japan
| | - Tetsuji Itoh
- Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Sendai, Miyagi 983-855, Japan
| | - Hirotomo Nishihara
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, Miyagi 980-8577, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, Miyagi 980-8577, Japan
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Shimizu S, Yoshii T, Nishikawa G, Wang J, Yin S, Kobayashi E, Nishihara H. Unlocking the chemical environment of nitrogen in perovskite-type oxides. Chem Sci 2024; 15:10350-10358. [PMID: 38994421 PMCID: PMC11234872 DOI: 10.1039/d4sc01850h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 05/15/2024] [Indexed: 07/13/2024] Open
Abstract
Nitrogen (N) doping of perovskite-type oxides is an effective method for enhancing their photocatalytic performance. Quantitative and qualitative analyses of the doped N species are essential for a deeper understanding of the catalytic activity enhancement mechanism. However, examining the N environment in perovskite-type oxides, particularly in the bulk, using conventional analytical techniques, such as X-ray photoelectron spectroscopy (XPS), is challenging. In this study, we propose a new analytical technique, advanced temperature-programmed desorption (TPD) up to 1600 °C, to complement the conventional methods. TPD can quantify all N species in bulk oxides. Moreover, it facilitates chemical speciation of N environments, such as substitutional and interstitial N species. This is verified by XPS, CHN elemental analysis, X-ray absorption spectroscopy, and in situ diffuse reflectance infrared Fourier-transform spectroscopy. This study demonstrates the feasibility of advanced TPD as a new analytical method that offers comprehensive information on the N species within N-doped oxide materials at the bulk level.
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Affiliation(s)
- Shunsuke Shimizu
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
| | - Takeharu Yoshii
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
| | - Ginga Nishikawa
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
| | - Jingwen Wang
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
- School of Environmental Science and Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University Shanghai 200240 P. R. China
| | - Shu Yin
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
| | - Eiichi Kobayashi
- Kyushu Synchrotron Light Research Center 8-7 Yayoigaoka, Tosu Saga 841-0005 Japan
| | - Hirotomo Nishihara
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
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Pirabul K, Zhao Q, Pan ZZ, Liu H, Itoh M, Izawa K, Kawai M, Crespo-Otero R, Di Tommaso D, Nishihara H. Silicon Radical-Induced CH 4 Dissociation for Uniform Graphene Coating on Silica Surface. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306325. [PMID: 38032161 DOI: 10.1002/smll.202306325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/05/2023] [Indexed: 12/01/2023]
Abstract
Due to the manufacturability of highly well-defined structures and wide-range versatility in its microstructure, SiO2 is an attractive template for synthesizing graphene frameworks with the desired pore structure. However, its intrinsic inertness constrains the graphene formation via methane chemical vapor deposition. This work overcomes this challenge by successfully achieving uniform graphene coating on a trimethylsilyl-modified SiO2 (denote TMS-MPS). Remarkably, the onset temperature for graphene growth dropped to 720 °C for the TMS-MPS, as compared to the 885 °C of the pristine SiO2. This is found to be mainly from the Si radicals formed from the decomposition of the surface TMS groups. Both experimental and computational results suggest a strong catalytic effect of the Si radicals on the CH4 dissociation. The surface engineering of SiO2 templates facilitates the synthesis of high-quality graphene sheets. As a result, the graphene-coated SiO2 composite exhibits a high electrical conductivity of 0.25 S cm-1. Moreover, the removal of the TMP-MPS template has released a graphene framework that replicates the parental TMS-MPS template on both micro- and nano- scales. This study provides tremendous insights into graphene growth chemistries as well as establishes a promising methodology for synthesizing graphene-based materials with pre-designed microstructures and porosity.
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Affiliation(s)
- Kritin Pirabul
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
| | - Qi Zhao
- Department of Chemistry, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Zheng-Ze Pan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
| | - Hongyu Liu
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
| | - Mutsuhiro Itoh
- Fuji Silysia Chemical Ltd., 2-1846 Kozoji-cho, Kasugai, Aichi, 487-0013, Japan
| | - Kenichi Izawa
- Fuji Silysia Chemical Ltd., 2-1846 Kozoji-cho, Kasugai, Aichi, 487-0013, Japan
| | - Makoto Kawai
- Fuji Silysia Chemical Ltd., 2-1846 Kozoji-cho, Kasugai, Aichi, 487-0013, Japan
| | - Rachel Crespo-Otero
- Department of Chemistry, University College London, 2020 Gordon St., London, WC1H 0AJ, UK
| | - Devis Di Tommaso
- Department of Chemistry, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Hirotomo Nishihara
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
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Yamamoto M, Goto S, Tang R, Yamazaki K. Toward three-dimensionally ordered nanoporous graphene materials: template synthesis, structure, and applications. Chem Sci 2024; 15:1953-1965. [PMID: 38332834 PMCID: PMC10848746 DOI: 10.1039/d3sc05022j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/23/2023] [Indexed: 02/10/2024] Open
Abstract
Precise template synthesis will realize three-dimensionally ordered nanoporous graphenes (NPGs) with a spatially controlled seamless graphene structure and fewer edges. These structural features result in superelastic nature, high electrochemical stability, high electrical conductivity, and fast diffusion of gases and ions at the same time. Such innovative 3D graphene materials are conducive to solving energy-related issues for a better future. To further improve the attractive properties of NPGs, we review the template synthesis and its mechanism by chemical vapor deposition of hydrocarbons, analysis of the nanoporous graphene structure, and applications in electrochemical and mechanical devices.
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Affiliation(s)
- Masanori Yamamoto
- Department of Chemical Science and Engineering, Tokyo Institute of Technology Ookayama 2-12-1 Meguro Tokyo 152-8550 Japan
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba Sendai 980-8577 Japan
| | - Shunsuke Goto
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba Sendai 980-8577 Japan
| | - Rui Tang
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba Sendai 980-8577 Japan
| | - Kaoru Yamazaki
- RIKEN Center for Advanced Photonics, RIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
- Institute for Materials Research, Tohoku University 2-1-1 Katahira, Aoba Sendai 980-8577 Japan
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Yamazaki K, Goto S, Yoshino S, Gubarevich A, Yoshida K, Kato H, Yamamoto M. Surface defect healing in annealing from nanoporous carbons to nanoporous graphenes. Phys Chem Chem Phys 2023. [PMID: 38019669 DOI: 10.1039/d3cp04921c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
Nanoporous graphene (NPG) materials have the pronounced electrochemical stability of the seamless graphene structures developed over the 3D space. We revisited the Raman spectra of nanoporous carbons (NPCs) synthesized using θ-/γ-Al2O3 templates and NPGs converted from NPCs by annealing at 1800 °C to identify the type and density of defects. We found that both the NPCs and NPGs mostly consist of single-layered graphene with a few single vacancies and Stone-Wales defects. The density of vacancy defect per hexagon in the graphene sheet is estimated to be 10-2 for NPCs, while the annealing reduced the value to 10-3-10-4 for NPGs. This supports the outstanding chemical and electrochemical stability of the novel porous carbon materials.
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Affiliation(s)
- Kaoru Yamazaki
- RIKEN Center for Advanced Photonics, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Shunsuke Goto
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Shunya Yoshino
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Anna Gubarevich
- Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
| | - Katsumi Yoshida
- Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
| | - Hideki Kato
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Masanori Yamamoto
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro, Tokyo 152-8550, Japan.
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