Electrochemical CO2 conversion to fuels on metal-free N-doped carbon-based materials: functionalities, mechanistic, and technoeconomic aspects

Alarming levels of carbon dioxide (CO2) emission are increasingly posing calamitous consequences of environmental destruction and climate change. CO2 reduction reactions (CO2RRs) to fuels are both kinetically and thermodynamically unfavorable. This necessitates cleaner technologies for addressing the root cause of this notorious gas and its negative outcome, which has become a complex global phenomenon. The N-doped carbon-based electrocatalysts remain the emergent class of novel, safe, efficient, earth-abundant carbon, and ecofriendly for CO2 conversion to fuels and chemicals. N-doping modifies the electronic properties of carbon materials to enhance the electrocatalytic CO2RR to useful products and offers high activity, selectivity, and efficiency by suitably tuning the N species. This study presents recent advancements on the N-doped carbon-based electrocatalysts for CO2RR. The first few parts present the uniqueness of N-doped carbon-based electrocatalysts prior to the methodology of N-doping and N-doped electrocatalytic active sites. These were followed by recent progresses in the field for the formation of CO, HCOOH/HCOO−, syngas, and multicarbon products. Unlike previous reports in the field, the other part discussed the key parameters for improving the performances of metal-free N-doped carbon materials for CO2RR. The roles of N-functionalities in the electrocatalytic activity and selectivity during CO2RR were also explained. The last section discussed detailed mechanistic aspects and technoeconomic analysis of major products of the CO2RR over N-doped carbon-based electrocatalysts. Conclusively, some critical questions and insight into designing efficient N-doped carbon materials and also for CO2RR, including challenges, and knowledge gaps, were provided for better advancement and full fledge of the field toward industrial applications.