Recent Developments in Polymeric Carbon Nitride-Derived Photocatalysts and Electrocatalysts for Nitrogen Fixation

Ammonia generation through N-2 molecule reduction under ambient conditions has attracted tremendous attention because of the enormous energy input and continuous CO2 emissions of the traditional Haber-Bosch process. Photocatalytic and electrocatalytic N-2 reduction reaction (NRR) to NH3 production using sustainable energy sources are fascinating approaches to respond to these issues. However, the state-of-the-art photocatalysis and electrocatalysis toward NH3 production is far away from the industrial requirement because of poor catalytic activity. Hence, rationally designed high-efficiency catalysts are urgently demanded to promote practical applications. Polymeric carbon nitride (PCN) has drawn considerable focus because of its unusual properties, such as visible-light response and high pyridinic nitrogen content. This Review provides the most recent progress on constructing PCN-based photocatalysts and electrocatalysts via various design strategies, including vacancy creations, doping, and incorporation, to mediate its applications in NRR. On the basis of theoretical simulations, the insights into mechanism pathways of photocatalytic and electrocatalytic NH3 evolution are presented to provide guidance for engineering PCN-based catalysts. Subsequently, the remaining challenges and future prospects of further development in this research field are also highlighted. It can be foreseen that this Review will shed some light on the development of more potential PCN-based catalysts toward NRR and offer instructive information for further understanding the structure-performance correlations.