Quantifying local pH changes in carbonate electrolyte during copper-catalysed [Formula: see text] electroreduction...

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Copper (Cu) is a unique transition metal catalyzing CO2 electroreduction to hydrocarbons and alcohols.
• Understanding reaction mechanisms and the catalyst's micro-environment is key to controlling product selectivity.
• Local pH and CO2 concentrations near the electrode significantly impact product formation.

Purpose of the Study:

• To introduce an in operando NMR technique for simultaneous in-situ measurement of local pH and CO2 concentration.
• To investigate the influence of applied potential and electrolyte buffer capacity on formate production during CO2 electroreduction.
• To experimentally validate theoretical models and emphasize the interplay between catalyst and electrolyte.

Main Methods:

• In operando Nuclear Magnetic Resonance (NMR) spectroscopy.
• Electrochemical carbon dioxide reduction experiments.
• Simultaneous measurement of electrode-vicinity pH and CO2 concentration.

Main Results:

• Demonstrated the capability of in operando NMR to monitor local pH and CO2 levels during electroreduction.
• Quantified the effect of applied potential and electrolyte buffering on formate formation.
• Provided experimental evidence supporting theoretical predictions regarding catalyst-electrolyte interactions.

Conclusions:

• The study highlights the critical role of the local micro-environment in copper-catalyzed CO2 electroreduction.
• In operando NMR is a powerful tool for mechanistic studies in electrocatalysis.
• Optimizing the catalyst-electrolyte interface is essential for enhancing selectivity in CO2 conversion.