Interlayer single-metal-atom coordinated porous boron nitride: Triggering p-d-p orbital hybridization for efficient electrocatalytic nitrate to ammonia reduction

Electrocatalytic nitrate reduction reaction (NO₃RR) represents a sustainable paradigm for simultaneous environmental remediation and green NH₃ production. While single-atom catalysts (SACs) exhibit immense promise for NO₃RR, precisely manipulating their localized orbital interactions to decode the underlying structure-activity relationships remains a critical challenge. Herein, using density functional theory (DFT) calculations, we designed a series of interlayer single-metal-atom coordinated porous boron nitride (IC-M/p-BN) acting as efficient electrocatalysts for NO₃RR. Interlayer metal confinement triggers robust interfacial p-d-p orbital hybridization, establishing an efficient electron relay that empowers surface-exposed non-metallic B sites to act as direct catalytic centers while effectively suppressing the competing HER, NRR and toxic NO/NO₂ byproducts. Crucially, this interfacial charge transfer drives a dynamic B sp²-to-sp³ reconfiguration, facilitating optimal NO₃^- activation. Benefiting from this mechanism, IC-Co/p-BN and IC-Ni/p-BN deliver outstanding NO₃RR activity (limiting potentials of -0.51 and -0.50 V vs. RHE), significantly outperforming their conventional h-BN counterparts. Furthermore, machine learning analysis identifies the work function as the fundamental descriptor governing NO₃^- adsorption, revealing the interfacial catalytic mechanism. Our work not only offers a robust design strategy for high-efficiency 2D confined SACs but also provides deeper insights into the dynamic NO₃^--to-NH₃ conversion mechanism at non-metallic interfaces.