Theoretical study on electrocatalytic carbon dioxide reduction over copper with copper-based layered double...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Electrochemical conversion of carbon dioxide (CO2) into fuels and chemicals offers a sustainable energy solution.
• Layered double hydroxides (LDHs) modified with copper species are promising electrocatalysts for CO2 reduction reaction (CO2RR).
• Understanding the atomic-level mechanisms is crucial for designing efficient CO2RR catalysts.

Purpose of the Study:

• To elucidate the electrocatalytic mechanism of CO2RR over various copper configurations (monoatoms, diatoms, clusters) supported on CuAl-Cl-LDH.
• To identify the active sites and determine the factors influencing product selectivity (C2H4 vs. C2H5OH).
• To evaluate the catalytic performance of different copper species for CO2 conversion.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model the CO2RR.
• Calculations included active site analysis, density of states, adsorption energies, charge density differences, and free energy profiles.
• Investigated five distinct catalytic systems: Cu@CuAl-Cl-LDH, Cu2@CuAl-Cl-LDH, Td-Cu4@CuAl-Cl-LDH, and Pl-Cu4@CuAl-Cl-LDH.

Main Results:

• All studied catalysts facilitate the generation of C2 products from CO2 reduction.
• Planar Cu4 clusters (Pl-Cu4@CuAl-Cl-LDH) favor ethanol (C2H5OH) production, while other structures predominantly yield ethylene (C2H4).
• The orthotetrahedral Cu4 cluster (Td-Cu4@CuAl-Cl-LDH) exhibited superior electrocatalytic performance with a maximum step height of 0.78 eV, attributed to its larger positively charged active site.

Conclusions:

• The selectivity towards C2H4 or C2H5OH is governed by the dehydration pathway of the *C2H2O intermediate.
• Positively charged copper species (Cuδ+) enhance CO2RR activity.
• This theoretical study provides valuable insights for the rational design of advanced CO2RR electrocatalysts, promoting energy efficiency and emission reduction.