Reverse pH-dependent fluorescence protein visualizes pattern of interfacial proton dynamics during hydrogen evolution...

Area of Science:

• Electrochemistry
• Biophysics
• Materials Science

Background:

• Reverse pH-dependent fluorescent proteins exhibit inverse chromophore protonation relative to external pH.
• This pH dependence persists even when the proteins are immobilized at metal-solution interfaces.
• The hydrogen evolution reaction (HER) typically increases local pH, but can induce deprotonation in these proteins via an interface-specific effect.

Purpose of the Study:

• To utilize the interface-specific deprotonation of reverse pH-dependent fluorescent proteins for real-time visualization of interfacial proton dynamics during HER.
• To differentiate HER-induced deprotonation from bulk solution pH changes.
• To investigate the influence of electrode configuration on proton depletion patterns and observe proton transport phenomena at the interface.

Main Methods:

• Employing dKeima, a reverse pH-dependent fluorescent protein, for wide-field, scanning-less imaging.
• Real-time monitoring of optical signals at the metal-solution interface during HER.
• Utilizing composite electrodes with catalysts to study interfacial proton dynamics.

Main Results:

• dKeima successfully visualized HER-driven deprotonation, distinguishing it from solution pH effects.
• Proton depletion patterns showed a strong dependence on electrode configuration in composite structures.
• Observed optical signal propagations suggest long-range proton hopping confined to the metal-solution interface.

Conclusions:

• Reverse pH-dependent fluorescent proteins offer a novel tool for spatiotemporal analysis of interfacial proton dynamics.
• This approach enhances understanding of the HER mechanism.
• The findings contribute to the development of safe and efficient molecular hydrogen production strategies.