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CO₂ Reduction Reaction (CO2RR)

The CO₂ Reduction Reaction converts carbon dioxide into valuable chemicals and fuels.

Overview

CO2RR can produce various products depending on the catalyst and conditions:

Product Electrons Pathway
CO 2e⁻ CO pathway
HCOOH 2e⁻ Formate pathway
CH₃OH 6e⁻ Methanol pathway
CH₄ 8e⁻ Methane pathway
C₂H₄ 12e⁻ Ethylene pathway

Supported Pathways

ASCICat supports three major CO2RR pathways:

CO Pathway

\[CO_2 + 2H^+ + 2e^- \rightarrow CO + H_2O\]

Key intermediate: *CO bound to surface

from ascicat import ASCICalculator

calc = ASCICalculator(reaction='CO2RR', pathway='CO')
Parameter Value
\(\Delta E_{opt}\) -0.67 eV
\(\sigma_a\) 0.15 eV
Window [-1.2, -0.2] eV

CHO Pathway (Methanol)

\[CO_2 + 6H^+ + 6e^- \rightarrow CH_3OH + H_2O\]

Key intermediate: *CHO bound to surface

calc = ASCICalculator(reaction='CO2RR', pathway='CHO')
Parameter Value
\(\Delta E_{opt}\) -0.48 eV
\(\sigma_a\) 0.15 eV
Window [-0.9, -0.1] eV

COCOH Pathway (Formate)

\[CO_2 + 2H^+ + 2e^- \rightarrow HCOOH\]

Key intermediate: *COOH bound to surface

calc = ASCICalculator(reaction='CO2RR', pathway='COCOH')
Parameter Value
\(\Delta E_{opt}\) -0.32 eV
\(\sigma_a\) 0.15 eV
Window [-0.7, 0.05] eV

Multi-Pathway Analysis

Screen across all pathways:

from ascicat import ASCICalculator
import pandas as pd

pathways = ['CO', 'CHO', 'COCOH']
all_results = {}

for pathway in pathways:
    calc = ASCICalculator(reaction='CO2RR', pathway=pathway)
    calc.load_data(f'data/CO2RR_{pathway}_clean.csv')
    results = calc.calculate_asci()
    all_results[pathway] = calc.get_top_catalysts(n=10)

# Compare top catalysts across pathways
for pathway, top in all_results.items():
    print(f"\n{pathway} Pathway - Top 3:")
    for i, (_, row) in enumerate(top.head(3).iterrows(), 1):
        print(f"  {i}. {row['symbol']} (ASCI={row['ASCI']:.3f})")

Benchmark Materials

CO Pathway

Material \(\Delta E_{CO}\) (eV) Selectivity
Au(111) -0.55 ~100% CO
Ag(111) -0.48 ~90% CO
Zn -0.60 ~80% CO

Formate Pathway

Material \(\Delta E_{COOH}\) (eV) Selectivity
Sn -0.45 ~90% HCOOH
Pb -0.50 ~80% HCOOH
Bi -0.38 ~95% HCOOH

Multi-Carbon Products

Material Products Notes
Cu(111) CH₄, C₂H₄, C₂H₅OH Unique multi-carbon activity
Cu-Ag C₂+ products Synergistic effect

Configuration Details

from ascicat.config import get_reaction_config

# Get all CO2RR configurations
for pathway in ['CO', 'CHO', 'COCOH']:
    config = get_reaction_config('CO2RR', pathway=pathway)
    print(f"\n{pathway} Pathway:")
    print(f"  Optimal: {config.optimal_energy} eV")
    print(f"  Width: {config.activity_width} eV")
    print(f"  Window: {config.activity_window}")

Selectivity Considerations

Competing HER

All CO2RR catalysts also catalyze HER. The competitive adsorption of H vs. CO₂ determines selectivity. ASCICat scores intrinsic activity but doesn't directly model selectivity.

To account for selectivity:

  1. Pre-filter catalysts known for high CO2RR selectivity
  2. Consider including a selectivity descriptor in custom analysis
  3. Use experimental validation for top candidates

Scientific References

  • Peterson, A. A. & Nørskov, J. K. J. Phys. Chem. Lett. 3, 251 (2012)
  • Nitopi, S. et al. Chem. Rev. 119, 7610 (2019)
  • Kuhl, K. P. et al. Energy Environ. Sci. 5, 7050 (2012)
  • Hansen, H. A. et al. J. Phys. Chem. Lett. 4, 388 (2013)