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Developing highly efficient carbon aerogels (CA) electrocatalysts based on transition metal‐nitrogen sites is critical for the CO2 electroreduction reaction (CO2RR). However, simultaneously achieving a high current density and high Faradaic efficiency (FE) still remains a big challenge. Herein, a series of unique 3D hierarchical cross‐linked nanostructured CA with metal‐nitrogen sites (MN, M = Ni, Fe, Co, Mn, Cu) is developed for efficient CO2RR. An optimal CA/N‐Ni aerogel, featured with unique hierarchical porous structure and highly exposed M‐N sites, exhibits an unusual CO2RR activity with a CO FE of 98% at −0.8 V. Notably, an industrial current density of 300 mA cm−2 with a high FE of 91% is achieved on CA/N‐Ni aerogel in a flow‐cell reactor, which outperforms almost all previously reported M‐N/carbon based catalysts. The CO2RR activity of different CA/N‐M aerogels can be arranged as Ni, Fe, Co, Mn, and Cu from high to low. In situ spectroelectrochemistry analyses validate that the rate‐determining step in the CO2RR is the formation of *COOH intermediate. A ZnCO2 battery is further assembled with CA/N‐Ni as the cathode, which shows a maximum power density of 0.5 mW cm−2 and a superior rechargeable stability. [ABSTRACT FROM AUTHOR]

Regulating the local environment and structure of metal center coordinated by nitrogen ligands (M‐N4) to accelerate overall reaction dynamics of the electrochemical CO2 reduction reaction (CO2RR) has attracted extensive attention. Herein, we develop an axial traction strategy to optimize the electronic structure of the M‐N4 moiety and construct atomically dispersed nickel sites coordinated with four nitrogen atoms and one axial oxygen atom, which are embedded within the carbon matrix (Ni‐N4‐O/C). The Ni‐N4‐O/C electrocatalyst exhibited excellent CO2RR performance with a maximum CO Faradic efficiency (FE) close to 100 % at −0.9 V. The CO FE could be maintained above 90 % in a wide range of potential window from −0.5 to −1.1 V. The superior CO2RR activity is due to the Ni‐N4‐O active moiety composed of a Ni‐N4 site with an additional oxygen atom that induces an axial traction effect. [ABSTRACT FROM AUTHOR]

The electrochemical carbon dioxide (CO2) reduction (ECR) represents one of the most promising technologies for CO2 conversion into value-added feedstock from carbon monoxide (CO) to a variety of hydrocarbons. As the raw material for Fischer–Tropsch synthesis, CO is one of the most desirable ECR products and has recently received extensive research attention. Although noble metal materials, such as Au and Ag, show high selectivity towards conversion of CO2 to CO, their relative scarcity and high cost seriously limit their practical commercial application. Nanostructured carbon-based non-precious metal electrocatalysts (Nano-CNMs) are of tremendous interest in the field of ECR catalysis due to their tunable structures and electronic properties. Herein, we present an overview of recent progress in the application of Nano-CNMs, mainly including heteroatom-doped carbon, transition metal–heteroatom co-doped carbon, and carbon-based hybrid materials, with emphasis on electrocatalytic conversion of CO2 to CO. We particularly focus on discussing the structure/composition–performance relationships with regard to the electronic structure, surface properties, doping content, and associated electrocatalytic performance of various Nano-CNMs. We outline the future research directions in the development of high-selectivity ECR electrocatalysts for CO production and the stringent challenges in fundamental research and industrial application. [ABSTRACT FROM AUTHOR]

Sn-based materials are identified as promising catalysts for the CO 2 electroreduction (CO2RR) to formate (HCOO - ). However, their insufficient selectivity and activity remain grand challenges. A new type of SnO 2 nanosheet with simultaneous N dopants and oxygen vacancies (V O -rich N-SnO 2 NS) for promoting CO 2 conversion to HCOO - is reported. Due to the likely synergistic effect of N dopant and V O , the V O -rich N-SnO 2 NS exhibits high catalytic selectivity featured by an HCOO - Faradaic efficiency (FE) of 83% at -0.9 V and an FE of > 90% for all C1 products (HCOO - and CO) at a wide potential range from -0.9 to -1.2 V. Low coordination Sn-N moieties are the active sites with optimal electronic and geometric structures regulated by V O and N dopants. Theoretical calculations elucidate that the reaction free energy of HCOO* protonation is decreased on the V O -rich N-SnO 2 NS, thus enhancing HCOO - selectivity. The weakened H* adsorption energy also inhibits the hydrogen evolution reaction, a dominant side reaction during the CO2RR. Furthermore, using the catalyst as the cathode, a spontaneous Galvanic Zn-CO 2 cell and a solar-powered electrolysis process successfully demonstrated the efficient HCOO - generation through CO 2 conversion and storage., (© 2020 Wiley-VCH GmbH.)