Nitrogen-doped metal-free carbon catalysts for (electro)chemical CO₂ conversion and valorisation

Carbon dioxide (CO2) is regarded as the main contributor to the greenhouse effect. As a potential strategy to mitigate its negative impacts, the reduction of CO2 is environmentally critical, economically meaningful and scientifically challenging. Concerns regarding anthropogenic emissions have recently sparked interest in the CO2 chemical transformation techniques. Being both thermodynamically and kinetically unfavorable, CO2 conversion generally requires efficient metal-based catalysts although they have multiple competitive disadvantages such as high costs, low availability and detrimental effects on the environment. A new class of catalysts based on earth-abundant carbon materials has been considered as an efficient, low-cost, metal-free alternative for both the capture and catalytic or electrocatalytic conversion of CO2. CO2 electrochemical reduction (CO2RR) offers a new and important pathway towards renewable energy storage and production of fuels, and CO2 cycloaddition with epoxides to cyclic or polymeric carbonates opens up new prospects for the production of polymers and fine chemicals. This review provides an overview of the progresses made in nitrogen-doped metal-free carbon catalysts for CO2 electrochemical conversion and CO2 conversion into cyclic carbonates into useful fuels and chemicals with a focus on the results underlying their mechanistic behavior, advantages and/or limitations of this metal-free N-doped carbon catalysts on CO2 conversion and valorisation.