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Hidden Isolated OH at the Charged Hydrophobic Interface Revealed by Two-Dimensional Heterodyne-Detected VSFG Spectroscopy
摘要： Water around hydrophobic groups mediates hydrophobic interactions that play key roles in many chemical and biological processes. Thus, the molecular-level elucidation of the properties of water in the vicinity of hydrophobic groups is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic ion/water interfaces, the tetraphenylborate-ion (TPB?)/water and tetraphenylarsonium-ion (TPA+)/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of the anionic TPB? interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen-bonded OH groups, which are hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of the cationic TPA+ interface only show the presence of usual hydrogen-bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region.
关键词： hydrophobic interfaces,sum-frequency generation,ultrafast spectroscopy,interfacial water,vibrational dynamics
更新于2025-09-23 15:21:01
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A salt-resistant Janus evaporator assembled from ultralong hydroxyapatite nanowires and nickel oxide for efficient and recyclable solar desalination
摘要： Solar energy-driven interfacial water evaporation is a promising energy utilization technology in the field of seawater desalination and water purification. However, the accumulation of salt on the heating surface severely impairs the water evaporation performance and long-time stability. Herein, we demonstrate a new kind of photothermal paper comprising a high-temperature-resistant paper made from ultralong hydroxyapatite nanowires and glass fibers and black nickel oxide (NiO) nanoparticles for solar energy-driven desalination. Owing to the high photothermal conversion ability, fast water transportation in the air-laid paper, and good heat insulation, the hydrophilic HN/NiO photothermal paper can achieve efficient, stable and recyclable water evaporation performance. In addition, a Janus HN/NiO photothermal paper based on hydrophobic sodium oleate-modified ultralong hydroxyapatite nanowires has been developed, and it has a high water evaporation efficiency of 83.5% under 1 kW m?2 irradiation. In particular, with the bottom hydrophobic ultralong hydroxyapatite nanowire layer and water-transporting channels in the air-laid paper to facilitate salt exchange, the as-prepared Janus evaporator exhibits no salt accumulation on the surface, high performance and long-time stable desalination using simulated seawater (3.5 wt% NaCl). Furthermore, the Janus evaporator with the hydrophobic ultralong hydroxyapatite nanowire substrate can be extended to support other photothermal materials such as black titanium oxide (Ti2O3) and Ketjen black carbon. The as-prepared Janus HN/Ti2O3 and Janus HN/KB photothermal paper also exhibit salt-resistant desalination function. The as-prepared Janus salt-resistant photothermal paper with efficient, stable and recyclable merits has great potential in solar energy-driven desalination and water purification.
关键词： desalination,interfacial water evaporation,water purification,solar energy-driven,photothermal paper,ultralong hydroxyapatite nanowires,nickel oxide
更新于2025-09-23 15:19:57
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Hidden isolated OH at the charged hydrophobic interface revealed by two-dimensional heterodyne-detected VSFG spectroscopy
摘要： Water around the hydrophobic groups mediates hydrophobic interaction that plays key roles in many chemical and biological processes. Thus, molecular-level elucidation of the properties of the water in the vicinity of the hydrophobic group is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic interfaces, i.e., the tetraphenylborate ion (TPB-)/water and tetraphenylarsonium ion (TPA+)/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of anionic TPB- interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen bonded OH groups, which is hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of cationic TPA+ interface only show the presence of usual hydrogen bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region.
关键词： sum-frequency generation,ultrafast spectroscopy,hydrophobic interfaces,interfacial water,vibrational dynamics
更新于2025-09-23 15:19:57
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Surface-Specific Spectroscopy of Water at a Potentiostatically Controlled Supported Graphene Monolayer
摘要： Knowledge of the structure of interfacial water molecules at electrified solid materials is the first step toward a better understanding of important processes at such surfaces, in, e.g., electrochemistry, atmospheric chemistry, and membrane biophysics. As graphene is an interesting material with multiple potential applications such as in transistors or sensors, we specifically investigate the graphene-water interface. We use sum-frequency generation spectroscopy to investigate the pH- and potential-dependence of the interfacial water structure in contact with a chemical vapor deposited (CVD)-grown graphene surface. Our results show that the SFG signal from the interfacial water molecules at the graphene layer is dominated by the underlying substrate and that there are water molecules between the graphene and the (hydrophilic) supporting substrate.
关键词： pH-dependence,interfacial water structure,graphene-water interface,sum-frequency generation spectroscopy,potential-dependence
更新于2025-09-11 14:15:04