Selective Photocatalytic CO ₂ Reduction to C ₂ H ₆ on a Ni–Au Diatomic Catalyst

Photoreduction of CO 2 to C 2 hydrocarbons is more valuable but challenging due to the multielectron transfer process and sluggish kinetics of the C–C coupling step, which requires the synergistic work of multiple active sites to achieve. Herein, we constructed a Ni–Au diatomic site on an In 2 O 3 support for selective CO 2 photoreduction to C 2 H 6 in a gas–solid system without a sacrificial agent. The catalyst demonstrated a C 2 H 6 production rate of 3.58 μmol g –1 h –1 with a selectivity of over 79.8%. A series of optoelectronic characterizations (especially in situ XPS) suggested that the Ni–Au dual-atom sites significantly enhanced the separation and transfer kinetics of photogenerated electron–hole pairs. Control experiments and in situ DRIFTS characterization revealed that the Au sites in the 1Ni0.5Au/In 2 O 3 catalyst promoted the C–C coupling step of the C 1 intermediate species, while the Ni sites significantly increased the local CO concentration around the active sites, synergistically promoting efficient C 2 H 6 production. This work provides insights into rationally designing synergistic catalysts with multiple active sites for selective CO 2 photoreduction into a high-value target product.