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 (U_L=−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.