Revealing the origin of activity and selectivity for Ti/g-C3N4 to ammonia production via nitrate reduction electrocatalysis: A first-principles study

Nitrate reduction reaction (NO3RR) is identified as a feasible solution to the current global nitrogen cycle imbalance. Here we explored the NO3RR catalytic performance of transition metal-immobilized single-atom catalysts on g-C3N4 by DFT. Preliminary screening work proved that Ti/g-C3N4 has the lowest limiting potential (UL=−0.3 V) and is the most potential single-atom catalyst for NO3RR. The reaction mechanism analysis of Ti/g-C3N4 also confirmed that it has the selectivity of NO3RR reaction to produce ammonia. This work also proved that the hydrogen evolution reaction does not pose a threat to the ammonia production for Ti/g-C3N4. It is worth mentioning that by analyzing the properties of Ti/g-C3N4 and 2Ti/g-C3N4, we found that the large spin polarization contributed to the excellent activity and selectivity of the NO3RR ammonia production reaction for Ti/g-C3N4. This work not only finds a new NO3RR catalyst (Ti/g-C3N4), but also provides a new idea for designing new NO3RR catalysts.