Programmable Single-Stranded DNA Layers as Modulators of Nanoscale pH at Electrocatalytic Interfaces

Area of Science:

• Electrochemistry
• Nanotechnology
• Materials Science

Background:

• Controlling the local reaction environment at electrocatalytic interfaces is critical for optimizing electrochemical reactions.
• Single-stranded DNA (ssDNA) with anionic phosphate backbones offers potential as a novel material for modulating these interfaces.

Purpose of the Study:

• To investigate the use of ssDNA layers as ionomer-like coatings for nanoscale control of the interfacial pH.
• To explore how ssDNA structure, specifically strand length and base-pairing, influences electrocatalytic activity and selectivity on gold nanoparticle (AuNP) electrocatalysts.

Main Methods:

• Fabrication of ssDNA layers on AuNP electrocatalysts with controlled thickness and base-pairing.
• Electrochemical characterization of hydrogen evolution and glycerol oxidation reactions.
• Structure-activity relationship analysis, including temperature-dependent studies and modified ssDNA constructs.
• Operando surface-enhanced Raman spectroscopy (SERS) to probe interfacial mechanisms.

Main Results:

• ssDNA layers effectively modulated the local pH and interfacial environment at the nanoscale.
• Electrocatalytic activity and selectivity for hydroxide ion (OH-) involving reactions were dependent on the ssDNA sequence and base-pairing.
• Base-pairing interactions within the ssDNA layer were identified as the primary factor governing catalytic performance.
• Operando SERS revealed an ssDNA-mediated Donnan exclusion mechanism for OH-.

Conclusions:

• ssDNA serves as a programmable platform for engineering nanoscale reaction environments in electrocatalysis.
• Design principles for ionomer-like architectures based on ssDNA can be developed for advanced electrocatalytic applications.
• The findings highlight the potential of DNA nanotechnology in controlling interfacial phenomena for catalysis.