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Electrochemically converting CO2 (CO2 reduction reaction(CO2RR)) to value‐added fuels is an advanced technology to effectively alleviate global warming and the energy crisis. However, thermodynamically high energy barriers, sluggish reaction kinetics, and inadequate CO2 conversion rate as well as poor selectivity of target products and rapid materials degradation severely limit its further large‐scale application, which highlights the importance of high‐performance electrocatalysts. Metal nanomaterials, due to their intrinsically high but still insufficient reactivity, selectivity, and stability, have been brought to the forefront and have lead to many reviews from various points of view. However, reviews which comprehensively unravel the importance and excellence of specific metal nanostructures and their associated properties for CO2RR are quite limited. To bridge this gap, various specific monometal and bimetal nanostructures are summarized, with an emphasis on the deep understanding of crystal orientation, surface structure, surface crystallography, surface modification, and many associated effects benefiting from the constructed specific metal nanostructures as well as the intrinsic relationships of specific metal nanostructure‐property‐CO2RR activities. Finally, the challenges and the perspectives to advance CO2RR are proposed to pay particularly more attention to architecture evolution during CO2RR with in situ/operando techniques, high‐throughput theoretical computations, and facile synthetic strategies with high yield and production for scale‐up applications.

Electrochemical CO2 reduction reaction (CO2RR), when powered with intermittent but renewable energies, holds an attractive potential to close the anthropogenic carbon cycle through efficiently converting the exorbitantly discharged CO2 to value-added fuels and/or chemicals and consequently reduce the greenhouse gas emission. Through systematically integrating the density functional theory calculations, the modeling statistics of various proportions of CO2RR-preferred electroactive sites, and the theoretical work function results, it is found that the crystallographically unambiguous Ag nanoclusters (NCs) hold a high possibility to enable an outstanding CO2RR performance, particularly at an optimal size of around 2 nm. Motivated by this, homogeneously well-distributed ultrasmall Ag NCs with an average size of ∼2 nm (2 nm Ag NCs) were thus synthesized to electrochemically promote CO2RR, and the results demonstrate that the 2 nm Ag NCs are able to achieve a significantly larger CO partial current density [j (CO)], an impressively higher CO Faraday efficiency of over 93.8%, and a lower onset overpotential (η) of 146 mV as well as a remarkably higher energy efficiency of 62.8% and a superior stability of 45 h as compared to Ag nanoparticles (Ag NPs) and bulk Ag. Both theoretical computations and experimental results clearly and persuasively demonstrate an impressive promotion effect of the crystallographically explicit atomic structure for electrochemically reducing CO2 to CO, which exemplifies a novel design approach to more benchmark metal-based platforms for advancing the practically large-scale CO2RR application.

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