CO₂ reduction reaction on Sc-doped nanocages as catalysts

The catalytic ability of Sc-doped C₄₆ and Sc-doped Al₂₃P₂₃ as catalysts of CO₂-RR to create the CH₄ and CH₃OH is investigated. The mechanisms of CO₂-RR are examined by theoretical methods and ΔG_reaction of reaction steps of CO₂-RR mechanisms are calculated. The overpotential of CH₄ and CH₃OH production on Sc-doped C₄₆ and Sc-doped Al₂₃P₂₃ is calculated. The Sc atoms of Sc-doped C₄₆ and Sc-doped Al₂₃P₂₃ can adsorb the CO₂ molecule as the first step of CO₂-RR. The CH₄ is produced from hydrogenation of *CH₃O and the *CO → *CHO reaction step is the rate limiting step for CH₄ production. The CH₃OH can be formed on Sc-doped C₄₆ and Sc-doped Al₂₃P₂₃ by *CO → *CHO → *CH₂O → *CH₃O → CH₃OH mechanism and HCOOH → *CHO → *CH₂O → *CH₃O → CH₃OH mechanism. The Sc-C₄₆ and Sc-Al₂₃P₂₃ can catalyze the CO₂-RR to produce the CH₄ and CH₃OH by acceptable mechanisms.

Here, the structures are optimized by PW91PW91/6-311+G (2d, 2p) and M06-2X/cc-pVQZ methods in GAMESS software. The frequencies of nanocages and their complexes with species of CO₂-RR are investigated by mentioned methods. The transition state of each reaction step of CO₂-RR is searched by Berny method to find the CO₂-RR intermediates. The ∆E_adsorption of intermediates of CO₂-RR on surfaces of nanocages is calculated and the ∆G_reaction of reaction steps of CO₂-RR is calculated.