Study on the Adsorption and Activation Behaviours of Carbon Dioxide over Copper Cluster (Cu₄) and Alumina-Supported Copper Catalyst (Cu₄/Al₂O₃) by means of Density Functional Theory

Table 5

The bond orders (B.O) and the binding energy of C–O (E_bind, kJ·mol⁻¹).

Parameters	CO2–Cu4 (tetrahedral): d2b	CO2–Cu4/Al2O3 (d2d)	CO2 (gas)
B.O (C–O)	1.197; 1.571	1.750; 1.910	1.915
B.O (O–Cu4)	0.420; 0.070	0.094; 0.097	−
B.O (C–Cu4)	0.785	0.149	−
B.O (CO2–Cu4)	1.275	0.340	−
Ebind (C–O)	669.56; 696.31	648.11; 632.58	716.54

Note: the total bond order between atoms of CO₂ and copper atoms.