Theoretical Insights\ninto the Efficient Reduction\nof Nitrate to Ammonia on Crystalline Carbon Nitride

The nitrate reduction reaction (NO<sub>3</sub>RR) has\nemerged as\na promising approach for wastewater treatment and ammonia (NH<sub>3</sub>) synthesis. Poly(triazine imide)/LiCl (PTI/LiCl), a highly\ncrystalline carbon nitride with a well-defined structure, has shown\nsignificant potential in this field. In this study, the electronic\nproperties and catalytic performance of PTI/LiCl for NO<sub>3</sub>RR were investigated through theoretical calculations. Band structure\nand projected density of states (PDOS) analyses show that the intercalation\nof Li<sup>+</sup> and Cl<sup>–</sup> ions within the PTI pores\nenhances electronic conductivity and improves its electronic properties.\nThe reduction of nitrate to NH<sub>3</sub> through a series of intermediates\non the PTI/LiCl (001) surface shows exothermic free energy changes\nfor each elementary step. The catalyst demonstrates outstanding selectivity\nand stability, effectively suppressing the competitive hydrogen evolution\nreaction and byproduct formation. Charge density difference and PDOS\nanalyses confirm the orbital interactions between absorbed NO<sub>3</sub> and Li ions. The study highlights the potential of PTI/LiCl\nas a low-cost, efficient electrocatalyst for NO<sub>3</sub>RR and\nprovides theoretical and practical insights for the design of environmentally\nfriendly catalysts.