Al-Doped Octahedral Cu 2 O Nanocrystal for Electrocatalytic CO 2 Reduction to Produce Ethylene.

Ethylene is an ideal CO 2 product in an electrocatalytic CO 2 reduction reaction (CO 2 RR) with high economic value. This paper synthesised Al-doped octahedral Cu 2 O (Al-Cu 2 O) nanocrystal by a simple wet chemical method. The selectivity of CO 2 RR products was improved by doping Al onto the surface of octahedral Cu 2 O. The Al-Cu 2 O was used as an efficient electrocatalyst for CO 2 RR with selective ethylene production. The Al-Cu 2 O exhibited a high % Faradic efficiency (FE C2H4 ) of 44.9% at -1.23 V (vs. RHE) in CO 2 saturated 0.1 M KHCO 3 electrolyte. Charge transfer from the Al atom to the Cu atom occurs after Al doping in Cu 2 O, optimizing the electronic structure and facilitating CO 2 RR to ethylene production. The DFT calculation showed that the Al-Cu 2 O catalyst could effectively reduce the adsorption energy of the *CHCOH intermediate and promote the mass transfer of charges, thus improving the FE C2H4 . After Al doping into Cu 2 O, the center of d orbitals shift positively, which makes the d-band closer to the Fermi level. Furthermore, the density of electronic states increases due to the interaction between Cu atoms and intermediates, thus accelerating the electrochemical CO 2 reduction process. This work proved that the metal doping strategy can effectively improve the catalytic properties of Cu 2 O, thus providing a useful way for CO 2 cycling and green production of C 2 H 4 .