Sustainable nitrogen photofixation: Considerations on the state of the art of non critical carbon materials

The achievement of a carbon-neutral energy economy is nowadays mandatory to face global warming and the current energy crisis. To mitigate the present and future environmental issues, replacing fossil feedstocks with renewable sources is of primary importance, aiming to meet future generations' demands for energy and commodities. In light of this, the revamp of the ammonia synthesis, which today consumes almost 2% of the energy globally produced, gained increasing interest. The ammonia generation by reacting air and water and using sunlight as an inexhaustible source of energy is the closest approach to the ideal situation for zero-carbon energy and chemical production. To promote solar-to-ammonia production, the photocatalyst plays a crucial role. However, for large-scale implementation and long-term utilization, the selection of noncritical raw materials in catalyst preparation is central aiming at resource security. In this context, herein are reviewed different strategies developed to improve the photocatalytic performances of carbon-based materials. The introduction of vacancies and surface doping are discussed as valuable approaches to enhance the photocatalytic activity in the nitrogen fixation reactions, as well as the construction of heterojunctions to finely tune the electronic properties of carbon-based materials.