Acidic Electrocatalytic CO₂ Reduction Using Space-Confined Nanoreactors.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Electrochemical CO2 reduction (CO2RR) is key for sustainable chemical synthesis.
• Conventional CO2RR in alkaline/neutral media suffers from carbonate formation, reducing efficiency.
• Acidic media presents challenges due to competing hydrogen evolution.

Purpose of the Study:

• To develop a space-confined strategy for efficient CO2RR in acidic media.
• To investigate the use of Ni nanoparticles encapsulated in N-doped carbon nanocages as yolk-shell nanoreactors.
• To understand the structure-performance relationship for selective CO2 conversion.

Main Methods:

• Synthesis of Ni nanoparticles encapsulated within N-doped carbon nanocages (yolk-shell nanoreactors).
• Electrochemical CO2 reduction reaction (CO2RR) experiments in acidic electrolytes (pH 2.5) and neutral electrolytes (pH 7.2).
• Utilizing a flow electrolysis system for continuous operation and performance evaluation.

Main Results:

• Achieved a Faradaic efficiency (FE) of 93.2% for CO at pH 7.2 and 84.3% for CO at pH 2.5.
• Demonstrated suppression of hydrogen evolution in acidic media due to inhibited proton diffusion within the nanoreactor's Nernst layer.
• Observed enhanced current density and sustainable operation in the acidic flow electrolysis system compared to neutral systems.

Conclusions:

• Space-confined CO2RR in acidic media using yolk-shell nanoreactors is a viable strategy for selective CO production.
• The unique nanostructure effectively steers mass transport, suppressing competing reactions.
• This work provides insights into catalyst design for efficient and sustainable CO2 conversion.