Synergistic Ni–P co-doping in pyrite FeS2 for efficient electrocatalytic nitrate reduction via a dissociative mechanism: a theoretical insight

Abstract

The electrocatalytic nitrate reduction reaction (NO₃RR) represents a sustainable strategy 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 natural 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 modulates 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. Detailed electronic analysis underscores a synergistic Ni-d/P-p ‘push–pull’ effect that triggers barrierless N–O bond cleavage, fundamentally optimizing the kinetic landscape for the NO₃⁻-to-NH₃ conversion. Furthermore, computed formation energies and ab initio molecular dynamics simulations confirm the robust thermodynamic and structural stability of Ni–P/FeS₂, suggesting its feasibility for experimental realization. Beyond identifying a promising NO₃RR catalyst, this work elucidates the fundamental role of metal–nonmetal synergy in governing complex multi-electron transfer processes, offering a robust paradigm for the rational design of advanced dual-site catalysts.