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Bhartia B, Jayaraman S, Troadec C, Madapusi SP, Puniredd SR. Grafting of Organophosphonic Acid Monolayers on Hydrogen-Terminated Silicon Surface and Secondary Functionalization in Supercritical Carbon Dioxide Media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12063-12074. [PMID: 37581455 DOI: 10.1021/acs.langmuir.3c01278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The monolayer grafting on the oxide-free Si surface is challenging due to vulnerability of the surface against oxide formation in an ambient atmosphere. Most of the conventional studies focused on organic solvent-based chemistry and solvent and substrate interfaces, and residual solvents after the monolayer grafting play a key role in producing the highly stable monolayers. CO2 in its supercritical state (SCCO2) provides an elegant engineering solution for the problem faced as it can be used as inert processing environment and as carrier fluid for monolayer grafting taking up the role of organic solvents. In this work, monolayers of alkyl organophosphonic acids (OPAs) and functional OPAs were grafted on hydrogen-terminated oxide-free Si surfaces using the SCCO2 process. Grafted monolayers were physically and chemically characterized to verify the successful monolayer formation and determine the nature of the covalent binding configuration on the surface. To broaden the prospects of practical utility of the process and the OPA monolayer, the (3-bromopropyl)phosphonic acid (BPPA) monolayer was demonstrated to undergo secondary functionalization by terminal group substitution to convert the Br terminal group to the OH terminal group and secondary monolayer grafting to assemble 4-fluorothiophenol on top of the BPPA monolayer. The ability of monolayers to sustain secondary functionalization processing qualitatively hints toward ordered and stable monolayers of OPAs. The developed SCCO2 process in this work presents a single-step, green, and scalable method to graft the OPA monolayer on oxide-free Si which can employed in the future for monolayer doping, highly selective biochemical sensors, and targeted biological interactions.
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Affiliation(s)
- Bhavesh Bhartia
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-3, Singapore 138634, Republic of Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore,4 Engineering Drive 4, Singapore 117585, Republic of Singapore
| | - Sundaramurthy Jayaraman
- YSQ International Pte Ltd, 401 Commonwealth Drive, #07-01, Singapore 149598, Republic of Singapore
| | - Cedric Troadec
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-3, Singapore 138634, Republic of Singapore
| | - Srinivasan Palavedu Madapusi
- Department of Chemical Engineering, BITS Pilani, Dubai Campus, Dubai International Academic City, P.O. Box No. 345055, Dubai 500001, UAE
| | - Sreenivasa Reddy Puniredd
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-3, Singapore 138634, Republic of Singapore
- Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos, #01-02, Singapore 138669, Republic of Singapore
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Ruan YC, Xie YM, Chen XL, Dong L, Zhang FF, Yang TT, Luo XF, Cheng MY, Yin PF, Dong CK, Lin K, Li DJ, Liu H, Du XW. Exposing Cu(100) Surface via Ion-Implantation-Induced Oxidization and Etching for Promoting Hydrogen Evolution Reaction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2993-2999. [PMID: 35212548 DOI: 10.1021/acs.langmuir.2c00083] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Metallic materials with unique surface structure have attracted much attention due to their unique physical and chemical properties. However, it is hard to prepare bulk metallic materials with special crystal faces, especially at the nanoscale. Herein, we report an efficient method to adjust the surface structure of a Cu plate which combines ion implantation technology with the oxidation-etching process. The large number of vacancies generated by ion implantation induced the electrochemical oxidation of several atomic layers in depth; after chemical etching, the Cu(100) planes were exposed on the surface of the Cu plate. As a catalyst for acid hydrogen evolution reaction, the Cu plate with (100) planes merely needs 273 mV to deliver a current density of 10 mA/cm2 because the high-energy (100) surface has moderate hydrogen adsorption and desorption capability. This work provides an appealing strategy to engineer the surface structure of bulk metallic materials and improve their catalytic properties.
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Affiliation(s)
- Yi-Chen Ruan
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Ya-Meng Xie
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xin-Lin Chen
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Lei Dong
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, China
| | - Fei-Fei Zhang
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Tian-Tian Yang
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xi-Feng Luo
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Mei-Yue Cheng
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Peng-Fei Yin
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Cun-Ku Dong
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Kui Lin
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - De-Jun Li
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, China
| | - Hui Liu
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xi-Wen Du
- Institute of New-Energy Materials, Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education Institution, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
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Study of the Molecule Adsorption Process during the Molecular Doping. NANOMATERIALS 2021; 11:nano11081899. [PMID: 34443729 PMCID: PMC8400913 DOI: 10.3390/nano11081899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/19/2021] [Accepted: 07/21/2021] [Indexed: 11/25/2022]
Abstract
Molecular Doping (MD) involves the deposition of molecules, containing the dopant atoms and dissolved in liquid solutions, over the surface of a semiconductor before the drive-in step. The control on the characteristics of the final doped samples resides on the in-depth study of the molecule behaviour once deposited. It is already known that the molecules form a self-assembled monolayer over the surface of the sample, but little is known about the role and behaviour of possible multiple layers that could be deposited on it after extended deposition times. In this work, we investigate the molecular surface coverage over time of diethyl-propyl phosphonate on silicon, by employing high-resolution morphological and electrical characterization, and examine the effects of the post-deposition surface treatments on it. We present these data together with density functional theory simulations of the molecules–substrate system and electrical measurements of the doped samples. The results allow us to recognise a difference in the bonding types involved in the formation of the molecular layers and how these influence the final doping profile of the samples. This will improve the control on the electrical properties of MD-based devices, allowing for a finer tuning of their performance.
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Germanium Nanowires as Sensing Devices: Modelization of Electrical Properties. NANOMATERIALS 2021; 11:nano11020507. [PMID: 33671353 PMCID: PMC8061886 DOI: 10.3390/nano11020507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 02/07/2023]
Abstract
In this paper, we model the electrical properties of germanium nanowires with a particular focus on physical mechanisms of electrical molecular sensing. We use the Tibercad software to solve the drift-diffusion equations in 3D and we validate the model against experimental data, considering a p-doped nanowire with surface traps. We simulate three different types of interactions: (1) Passivation of surface traps; (2) Additional surface charges; (3) Charge transfer from molecules to nanowires. By analyzing simulated I–V characteristics, we observe that: (i) the largest change in current occurs with negative charges on the surfaces; (ii) charge transfer provides relevant current changes only for very high values of additional doping; (iii) for certain values of additional n-doping ambipolar currents could be obtained. The results of these simulations highlight the complexity of the molecular sensing mechanism in nanowires, that depends not only on the NW parameters but also on the properties of the molecules. We expect that these findings will be valuable to extend the knowledge of molecular sensing by germanium nanowires, a fundamental step to develop novel sensors based on these nanostructures.
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