Controlled Synthesis of Intermetallic Au₂Bi Nanocrystals and Au₂Bi/Bi Hetero-Nanocrystals with Promoted Electrocatalytic CO₂ Reduction Properties

The electrocatalytic properties of metal nanoparticles (NPs) strongly depend on their compositions and structures. Rational design of alloys and/or heterostructures provides additional approaches to modifying their surface geometric and electronic structures for optimized electrocatalytic performance. Here, a solution synthesis of freestanding intermetallic Au₂Bi NPs, the heterostructures of Au₂Bi/Bi hetero-NPs, and their promoted electrocatalytic CO₂ reduction reaction (CO₂RR) performances were reported. It was revealed that the formation and in-situ conversion of heterogeneous seeds (e. g., Au) were of vital importance for the formation of intermetallic Au₂Bi and Au₂Bi/Bi hetero-NPs. It was also found that the Au components would act as the structure promoter moderating the binding strength for key intermediates on Bi surfaces. The alloying of Bi with Au and the formation of heterogeneous Au₂Bi/Bi interfaces would create more surface active sites with modulated electronic structures and stronger adsorption strengths for key intermediates, promoting the CO₂-to-HCOOH conversion with high activity and selectivity. This work presents a novel route for preparing intermetallic nanomaterials with modulated surface geometric/electric structures and promoting their electrocatalytic activities with alloying effects and interfacial effects. Such strategy may find wide application in catalyst design and synthesis for more electrocatalytic reactions.