Theoretical Insights into the Efficient Reduction of Nitrate to Ammonia on Crystalline Carbon Nitride

Abstract

The nitrate reduction reaction (NO₃RR) has emerged as a promising approach for wastewater treatment and ammonia (NH₃) synthesis. Poly(triazine imide)/LiCl (PTI/LiCl), a highly crystalline carbon nitride with a well-defined structure, has shown significant potential in this field. In this study, the electronic properties and catalytic performance of PTI/LiCl for NO₃RR were investigated through theoretical calculations. Band structure and projected density of states (PDOS) analyses show that the intercalation of Li⁺ and Cl^– ions within the PTI pores enhances electronic conductivity and improves its electronic properties. The reduction of nitrate to NH₃ through a series of intermediates on the PTI/LiCl (001) surface shows exothermic free energy changes for each elementary step. The catalyst demonstrates outstanding selectivity and stability, effectively suppressing the competitive hydrogen evolution reaction and byproduct formation. Charge density difference and PDOS analyses confirm the orbital interactions between absorbed NO₃ and Li ions. The study highlights the potential of PTI/LiCl as a low-cost, efficient electrocatalyst for NO₃RR and provides theoretical and practical insights for the design of environmentally friendly catalysts.