Adsorption behaviors and vibrational spectra of hydrogen peroxide molecules at quartz/water interfaces

Abstract

The effect of HO concentration on the change of H-bonds at a water/quartz interface was systematically examined by surface-specific sum-frequency generation (SFG) spectroscopy. Molecular dynamics (MD) simulation was further utilized to interpret the specific molecular dynamics as well as the configuration and evolution of water and HO molecules at the interface. The results from this study demonstrated the important role of surface H-bonds on determination of the stability of adsorbed HO at solvated, silica, xerogel surfaces. It was revealed that prior to reaching the surface saturation with HO molecules (less than 20% in bulk solution), multiple H-bonds were formed with silanols at relatively short interactive distances. These H-bonds proved to be strong enough to enable the overall stability of adsorbed HO. However, once saturated, the HO molecules would be adsorbed at longer distances away from the surface, and could easily migrate to the bulk solution; therefore, in this case, the bonds failed to support stable HO adsorption. These new findings explained the detailed molecular mechanism of the relationship between HO concentration and HO stability in HO-silica xerogels. This solves the current challenge of effective HO storage, and provides fundamental insight for predicting the adsorption behavior of HO at the silica surface.

Potassium Hydroxide Concentration-Dependent Water Structure on the Quartz Surface Studied by Combining Sum-Frequency Generation (SFG) Spectroscopy and Molecular Simulations

“…The SFG spectra of the quartz/water interface in the O–H stretch region were measured, and the SFG spectra setup had been described elsewhere. , Briefly, two overlapped input beams were used, one was fixed at visible wavelength 532 nm and the other was tunable in the infrared regime between 2.3 and 10 μm, with typical energies of ∼200 mJ and ∼100 mJ, respectively. The pulses had a width of ∼20 ps.…”

“…Despite the broad impact of interfacial water structure, the lack of experimental techniques to study the buried solid/liquid interface at the molecular level has been an obstacle to expand our knowledge in understanding the surface interactions as well as molecule structures at the surface . However, the development of the sum-frequency generation (SFG) spectroscopy technique has provided an opportunity for researchers to explore surface/interface molecular structure with great versatility. , SFG is a second-order nonlinear optical process, which is prohibited in centrosymmetric media, e.g., bulk aqueous and quartz, but allowed at noncentrosymmetric interfaces, making SFG spectroscopy an intrinsically in situ probe of changes at the interface.…”

“…14 However, the development of the sum-frequency generation (SFG) spectroscopy technique has provided an opportunity for researchers to explore surface/interface molecular structure with great versatility. 15,16 SFG is a second-order nonlinear optical process, which is prohibited in centrosymmetric media, e.g., bulk aqueous and quartz, but allowed at noncentrosymmetric interfaces, making SFG spectroscopy an intrinsically in situ probe of changes at the interface.…”

The Attraction of Water for Itself at Hydrophobic Quartz Interfaces

“…Herein, using MD simulations we probed the perturbation of aqueous water structure in close proximity to model hydrophobic and hydrophilic quartz interfaces. Our interest in quartz-aqueous water interfaces stemmed from their ubiquitousness in nature and recent studies on quartz from structural, [29][30][31] wettability, 32,33 and theoretical 17,[34][35][36][37][38][39][40] perspectives.…”

Real-Time Monitoring of Azo Dye Interfacial Adsorption at Silica–Water Interface by Total Internal Reflection-Induced Surface Evanescent Wave

“…A number of different methods have been developed to study the adsorption behavior of chemicals at the silica–water interface. Most commonly, optical techniques are used, which including atomic force microscopy (AFM), quartz crystal microbalance-dissipation (QCM-D), spectroscopic ellipsometry (SE) and neutron reflection (NR). − Meanwhile, some likewise spectroscopic techniques are also employed, which include solid-state nuclear magnetic resonance (NMR), electron spin resonance (EPR), single-molecule total internal reflection fluorescence microscopy, dual polarization interferometry (DPI), Raman spectroscopy, and surface-specific sum-frequency generation (SFG) spectroscopy …”