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The electrochemical reductive valorization of CO2, referred to as the CO2RR, is an emerging approach for the conversion of CO2‐containing feeds into valuable carbonaceous fuels and chemicals, with potential contributions to carbon capture and use (CCU) for reducing greenhouse gas emissions. Copper surfaces and graphene‐embedded, N‐coordinated single metal atom (MNC) catalysts exhibit distinctive reactivity, attracting attention as efficient electrocatalysts for CO2RR. This review offers a comparative analysis of CO2RR on copper surfaces and MNC catalysts, highlighting their unique characteristics in terms of CO2 activation, C1/C2(+) product formation, and the competing hydrogen evolution pathway. The assessment underscores the significance of understanding structure–activity relationships to optimize catalyst design for efficient and selective CO2RR. Examining detailed reaction mechanisms and structure‐selectivity patterns, the analysis explores recent insights into changes in the chemical catalyst states, atomic motif rearrangements, and fractal agglomeration, providing essential kinetic information from advanced in/ex situ microscopy/spectroscopy techniques. At the end, this review addresses future challenges and solutions related to today's disconnect between our current molecular understanding of structure–activity‐selectivity relations in CO2RR and the relevant factors controlling the performance of CO2 electrolyzers over longer times, with larger electrode sizes, and at higher current densities. [ABSTRACT FROM AUTHOR]

Electrocatalysis could be a promising approach to produce valuable chemical compounds from carbon and nitrogen reactants. However, several challenges related to activity and selectivity need to be addressed to make these conversion energy and cost-efficient. The NO X reduction is an important reaction for denitrification and here we elucidate how the reaction mechanism controls the product distribution. We investigated the reduction reaction on a series of transition metals (Cu, Ni, Co, Fe, and Mn) to understand the factors governing the associative and dissociative reaction paths. While Cu favors the associative protonation path, the NO 3 − and NO 2 − reduction on Ni, Co, Fe, and Mn surfaces favor the dissociative reaction pathway. Comparing our DFT computed results with experimental data we found that apart from competing HER the adsorption of *NO 2 and its N-O dissociation barrier are two key factors for selective NO 3 − reduction towards ammonia and NO 2 −. These strategies could be extended to understand energetically robust reactions like N 2 and CO 2 reduction reactions. [Display omitted] • NO X reduction mechanism on Mn, Fe, Co, Ni and Cu and their oxide surfaces. • Cu and Ag bind NO 3 − weakly and favor the protonation path giving NO 2 − at low potential. • Mn, Fe, Co and Ni bind NO 3 − strongly and favor dissociation which leads to NH 3 selectivity. • The change in product distribution is driven by the interplay between electro and thermal steps. [ABSTRACT FROM AUTHOR]