Herein, worm-like Au nanoparticles have been prepared via a potential-cycling method by using Au foil as a counter electrode. The resulting catalyst exhibits high electrocatalytic CO 2 reduction activity in 0.1 KHCO 3 over a large potential range, achieving maximum Faradaic efficiency of 92% at −0.5 V versus reversible hydrogen electrode and 48-h durability. [Display omitted] • Worm-like Au nanoparticles anchored to 3D graphene foam were synthesized using a potential-cycling method. • The catalyst shows an outstanding CO 2 reduction performance over a large potential range in 0.1 M KHCO 3. • The catalyst achieved an optimal Faradaic efficiency of CO reaching 92% at −0.5 V vs RHE with more than 48-h stability. Highly efficient and selective conversion of CO 2 into a reusable form is desirable to the sustainable production of valuable chemicals out of greenhouse gases. Metal-based electrocatalysts often suffer from poor product selectivity for CO 2 reduction, and the activity is always limited to a narrow potential range. In this study, the worm-like Au nanoparticles anchored to three-dimensional (3D) graphene foam were synthesized via a potential-cycling method, termed as Au/GF. It can high-efficient catalyze CO 2 reduction to CO in aqueous 0.1 M KHCO 3 at the potential range of −0.2 V to −0.7 V versus reversible hydrogen electrode (vs RHE). At −0.5 V vs RHE, the reduction Faradaic efficiency (FE) reaches 92% and stays at this level for 48 h without any noticeable decay. The work promotes a facile strategy for nano-Au electrode production toward efficient and selective CO 2 reduction to CO. [ABSTRACT FROM AUTHOR]