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

The conversion of CO into valuable fuels and multi-carbon chemical substances by electrical energy is an effective strategy to solve environmental problems by using renewable energy sources. In this work, the density functional theory (DFT) method is used to reveal the electrocatalytic mechanism of CO reduction reaction (CORR) over the surface of CuAl-Cl-layered double hydroxides (LDHs) with Cu monoatoms (Cu@CuAl-Cl-LDH), Cu diatoms (Cu@CuAl-Cl-LDH), orthotetrahedral Cu clusters (Td-Cu@CuAl-Cl-LDH) and planar Cu clusters (Pl-Cu@CuAl-Cl-LDH). The active sites, density of states, adsorption energy, charge density difference and free energy are calculated. The results show that CORR over all the above five catalysts can generate C products. Pl-Cu@CuAl-Cl-LDH tends to generate CHOH, while the remaining four structures all tend to produce CH. Cu favors CORR, and Td-Cu@CuAl-Cl-LDH with a larger positively charged area at the active site has the better electrocatalytic performance among the calculated systems with a maximum step height of 0.78 eV. The selectivity of the products CH and CHOH depends on the dehydration of the intermediate *CHO to *CHO or *CCH; if the dehydration produces *CCH intermediate, the final product is CH, and if no dehydration occurs, CHOH is produced. This work provides theoretical information and guidance for further rational design of efficient CORR catalysts for energy saving and emission reduction.