Synergistic Ni–P Co-doping in Pyrite FeS2 for Efficient Electrocatalytic Nitrate Reduction via a Dissociative Mechanism: A Theoretical Insight

Abstract

The electrocatalytic reduction of nitrate (NO3RR) represents a sustainable frontier for wastewater remediation and green ammonia production; however, its efficiency is frequently constrained by sluggish N–O bond cleavage and competitive hydrogen evolution (HER). Inspired by the multi-site enzymatic cascades in nature, we propose a rational co-doping strategy to modulate the dual active sites of pyrite FeS2 for enhanced NO3RR performance. Through comprehensive density functional theory (DFT) computations, we demonstrate that the synergistic integration of Ni and P dopants significantly regulates the electronic structure of the Fe–S motifs, facilitating a highly efficient dissociative mechanism. Our results reveal that the Ni–P/FeS2 catalyst exhibits a low limiting potential of −0.28 V, where the Ni–P dual sites cooperatively drive the sequential deoxygenation of NO3- and NO2* intermediates. Detailed electronic analysis underscores that the superior activity originates from the optimal d-band center of metal and the p-band of. Furthermore, computed formation energies and ab initio molecular dynamics simulations confirm the robust thermodynamic and structural stability of Ni–P/FeS2, suggesting its high accessibility for experimental realization. Beyond identifying a promising NO3RR catalyst, this work elucidates the fundamental role of metal–nonmetal synergies in governing complex multi-electron transfer processes, offering a robust paradigm for the rational design of advanced dual-site catalysts.