2D monolayer electrocatalysts for CO₂ electroreduction

The electrocatalytic carbon dioxide reduction reaction (CO₂RR) is an attractive method for converting atmospheric CO₂ into value-added chemicals and fuels. In order to overcome the low efficiency and durability that hinder its practical application, a significant amount of research has been dedicated to designing novel catalysts at the nanoscale and even the atomic scale. Two-dimensional (2D) monolayer materials inherit the merits of both 2D materials and single-atom materials. Through bridging the gap between heterogeneous and homogeneous catalysis, 2D monolayer materials exhibit great potential in the CO₂RR due to their unique structural/electronic properties, high atom utilization, low mass transfer resistance and uniform active sites. Here, we systematically overview the development and application of 2D monolayer catalysts for the electrocatalytic CO₂RR. First, an overview of the CO₂RR technology is presented. Subsequently, a comprehensive discussion is undertaken on various types of 2D monolayer electrocatalysts, such as 2D graphene-based materials, 2D monolayer metal-organic frameworks (MOFs), 2D monolayer covalent organic frameworks (COFs) and 2D monolayer metal-based materials. Their respective electrocatalytic performances are also systematically analyzed. More importantly, novel perspectives on the primary challenges and opportunities associated with the utilization of 2D monolayer materials in the CO₂RR are presented. Achieving high-quality 2D monolayer materials and producing highly selective multi-carbon products remain the two major challenges in the design, synthesis and application of 2D monolayer electrocatalysts. Addressing these synthesis-related and performance-related issues is significant for the progression and practical utilization of 2D monolayer materials in the CO₂RR.