Direct observation of anomalous water at the solid-liquid boundary on silica surface

Abstract

In this study, we investigate the properties and behavior of interfacial water on solid silica surfaces and its implications for various applications. We utilize a combination of transmission electron microscopy (TEM), nuclear magnetic resonance, mass spectrometry, infrared, and Raman spectroscopy to explore the presence and characteristics of anomalous water on silica surfaces. Our findings reveal a stable, nanoscale layer of wall-bound water on the inner surface of silica tubes that persists under high vacuum and room temperature conditions. This layer is rich in hydrated hydrogen ions and exhibits a thickness that correlates with the density of hydroxyl groups in silica. Through additional experimentation, we demonstrate that reducing the density of silica hydroxyl groups causes the wall-bound water to return to a liquid state, highlighting the pivotal role of hydroxyl groups in the formation of this unique water layer. Our study offers valuable insights into the properties and behavior of interfacial water on solid surfaces and lays the foundation for potential applications in a wide range of fields, such as energy storage, drug delivery, environmental remediation, biological sample preparation, microfluidics, and nanofluidics. Future research will further explore the properties and behavior of interfacial water on different material surfaces and under various environmental conditions, laying the groundwork for technological innovation in related fields. By utilizing advanced approaches and fostering interdisciplinary collaboration, this research contributes significantly to our understanding of interfacial water and paves the way for the development of cutting-edge technologies that capitalize on its distinctive properties.