Enhanced C-C coupling in CO2 electroreduction on dual-atom catalysts modified by bridge O/OH

Due to their high economic value, C2 products are highly desirable as the products of the CO2 electroreduction reaction (CO2RR). In order to convert CO2 to C2 products, dual-atom catalysts (DACs) supported on N-doped carbon frameworks are expected as potential catalysts. However, it has remained challenging to observe C2 products generated on DACs in experiments. Considering that C-C coupling is the crucial step for the generation of C2 products, it is necessary to explore methods for enhancing C-C coupling on DACs. We present a computational study focusing on C-C coupling reactions occurring on O/OH-bridged Co and Ni dimers supported by Ndoped graphene (Co2@N6O, Co2@N6OH, Ni2@N6O and Ni2@N6OH). Three patterns of C-C coupling, denoted as *CO-*CO ->*COCO, *CO-*COH ->*COCOH, and *CO-*CHO -> *COCHO, are investigated. For Co2@N6 and Ni2@N6, only *CO-*CHO -> *COCHO on Ni2@N6 is feasible. After modified by O/OH, *CO-*CO ->*COCO and *CO-*CHO -> *COCHO on Co2@N6O, Co2@N6OH and Ni2@N6OH occur. O/OH and dual-atom catalysts could form a three-membered ring, thereby reducing the interaction of C and metal atoms, which facilitates the attachment of two C atoms for C-C coupling. All the results indicate that the presence of bridge O/OH can effectively enhance C-C coupling on Ni and Co dimer.