Pre-Protonation Reaction Pathway for CO₂ Electrolysis to n-Propanol.

Area of Science:

• Electrochemistry
• Catalysis
• Renewable Energy Storage

Background:

• Electrocatalytic CO2 reduction to n-propanol faces challenges due to high energy barriers in C-C coupling and competition from C2 products, leading to low selectivity.
• Existing methods struggle to efficiently convert CO2 into high-energy-density fuels like n-propanol.

Purpose of the Study:

• To develop a novel preprotonation reaction pathway to overcome limitations in n-propanol electrosynthesis.
• To enhance the selectivity and efficiency of converting CO2 into n-propanol using a mixed-coordination copper catalyst.

Main Methods:

• Utilized a mixed-coordination copper catalyst featuring high-coordination copper sites (HCN-Cu) and low-coordination copper sites (LCN-Cu).
• Investigated a preprotonation pathway involving CO spillover from HCN-Cu to LCN-Cu sites.
• Employed Density Functional Theory (DFT) calculations to analyze reaction energy barriers and mechanisms.

Main Results:

• The novel pathway facilitates preprotonation of C1 and C2 intermediates at LCN-Cu sites, circumventing high-energy CO-CO coupling.
• DFT calculations confirmed a shift in the rate-determining step from C-C coupling to *COH formation, reducing the energy barrier from 1.63 to 0.98 eV.
• Achieved a record-high n-propanol Faradaic selectivity of 17.6% due to enhanced C3 formation and mitigated C2 product competition.

Conclusions:

• The preprotonation pathway in mixed-coordination copper catalysts significantly enhances n-propanol selectivity.
• This approach offers a promising strategy for efficient storage of renewable electricity via CO2 electroreduction.
• The findings pave the way for developing advanced catalysts for sustainable chemical synthesis.