Gate Alignment of Liquid Water Molecules in Electric Double Layer

The behavior of liquid water molecules near an electrified interface is important to many disciplines of science and engineering. In this study, we applied an external gate potential to the silica/water interface via an electrolyte-insulator-semiconductor (EIS) junction to control the surface charging state. Without varying the ionic composition in water, the electrical gating allowed an efficient tuning of the interfacial charge density and field. Using the sum-frequency vibrational spectroscopy, we found a drastic enhancement of interfacial OH vibrational signals at high potential in weakly acidic water, which exceeded that from conventional bulk-silica/water interfaces even in strong basic solutions. Analysis of the spectra indicated that it was due to the alignment of liquid water molecules through the electric double layer, where the screening was weak because of the low ion density. Such a combination of strong field and weak screening demonstrates the unique tuning capability of the EIS scheme, and would allow us to investigate a wealth of phenomena at charged oxide/water interfaces.

Modulating the Pro-apoptotic Activity of Cytochrome c at a Biomimetic Electrified Interface

<p>Programmed cell death <i>via</i> apoptosis is a natural defence against excessive cell division, crucial at all stages of life from foetal development to maintenance of homeostasis and elimination of precancerous and senescent cells. Here we demonstrate an electrified liquid bio-interface that replicates the molecular machinery of the inner mitochondrial membrane at the onset of apoptosis. By mimicking <i>in vivo</i> cytochrome <i>c</i> (Cyt <i>c</i>) interactions with cell membranes, our platform allows us to modulate the conformational plasticity of the protein by simply varying the electrochemical environment at an aqueous|organic interface. As proof-of-concept, we use our electrified liquid bio-interface to identify drug molecules that can potentially downregulate Cyt <i>c</i> and protect against uncontrolled neuronal cell death in Alzheimer’s disease and other neurodegenerative disorders.</p>

Modulating the Pro-apoptotic Activity of Cytochrome c at a Biomimetic Electrified Interface

<p>Programmed cell death <i>via</i> apoptosis is a natural defence against excessive cell division, crucial at all stages of life from foetal development to maintenance of homeostasis and elimination of precancerous and senescent cells. Here we demonstrate an electrified liquid bio-interface that replicates the molecular machinery of the inner mitochondrial membrane at the onset of apoptosis. By mimicking <i>in vivo</i> cytochrome <i>c</i> (Cyt <i>c</i>) interactions with cell membranes, our platform allows us to modulate the conformational plasticity of the protein by simply varying the electrochemical environment at an aqueous|organic interface. As proof-of-concept, we use our electrified liquid bio-interface to identify drug molecules that can potentially downregulate Cyt <i>c</i> and protect against uncontrolled neuronal cell death in Alzheimer’s disease and other neurodegenerative disorders.</p>

Enhancing the Catalysis of Oxygen Reduction Reaction via Tuning Interfacial Hydrogen Bonds

Proton activity at the electrified interface is central to the kinetics of proton-coupled electron transfer (PCET) reactions for making chemicals and fuels. Here we employed a library of protic ionic liquids in an interfacial layer on Pt and Au to alter local proton activity, where the intrinsic ORR activity was enhanced up to 5 times, exhibiting a volcano-shaped dependence on the pKa of the ionic liquid. The enhanced ORR activity was attributed to favorable proton transfer kinetics for strengthened hydrogen bonds between the ionic liquid to the ORR product with comparable pKa. This proposed mechanism was supported by in situ surface-enhanced Fourier-Transform Infrared Spectroscopy and our simulation of PCET kinetics based on computed proton vibrational wavefunction at the H-bond interface. These findings highlight opportunities in using non-covalent interactions of hydrogen bond structures and solvation environments at the electrified interface to tune the kinetics of ORR and beyond.

Multimodal spectroscopic investigation of the conformation and local environment of biomolecules at an electrified interface

A combination of mid-infrared plasmons and time-resolved fluorescence are used to probe biomolecules at a buried electrochemically active interface.

Atomic Force Spectroscopy on Ionic Liquids

Ionic liquids have become of significant relevance in chemistry, as they can serve as environmentally-friendly solvents, electrolytes, and lubricants with bespoke properties. In particular for electrochemical applications, an understanding of the interface structure between the ionic liquid and an electrified interface is needed to model and optimize the reactions taking place on the solid surface. As with ionic liquids, the interplay between electrostatic forces and steric effects leads to an intrinsic heterogeneity, as the structure of the ionic liquid above an electrified interface cannot be described by the classical electrical double layer model. Instead, a layered solvation layer is present with a structure that depends on the material combination of the ionic liquid and substrate. In order to experimentally monitor this structure, atomic force spectroscopy (AFS) has become the method of choice. By measuring the force acting on a sharp microfabricated tip while approaching the surface in an ionic liquid, it has become possible to map the solvation layers with sub-nanometer resolution. In this review, we provide an overview of the AFS studies on ionic liquids published in recent years that illustrate how the interface is formed and how it can be modified by applying electrical potential or by adding impurities and solvents.

Water distribution at the electrified interface of deep eutectic solvents

Preferential asymmetric electrosorption of water onto a moderately polarized electrode surface.

Contemporary approaches in development of new materials for electrochemical energy conversion

The development of modern society is followed by increasing energy demands, highlighting the importance of sustainability of the energy system. In line with this task, electrochemistry has been set in the centre of modern research, offering a large number of solutions for energy conversion and storage. One of the main problems is the identification of new electrocatalytic materials which are used for energy conversion applications. A brief view on the use of modern computational techniques in discovery of new electrocatalysts is provided, mainly focusing on the electronic structure methods and the idea of catalytic descriptor. Using this approach, it is possible to screen many candidates for new electrocatalysts. However, the complexity of an electrified interface requires additional efforts to fully understand the properties of electrocatalytic materials.