Unlocking electrocatalytic dynamics with anti-MXene borides monolayers for nitrate reduction

[Display omitted] •Anti-MXene TMB monolayers exhibit exceptional stability for NO3RR.•MnB, RhB, and IrB show remarkable catalytic efficiency with low limiting potentials.•NO3RR pathways reveal a preference for N2 formation on MnB and NH3 on RhB and IrB.•CoB, FeB, and OsB can form both N2 and NH3, with CoB also demonstrating low limiting potentials. In this comprehensive study, we explore the electrocatalytic behavior of novel two-dimensional (2D) monolayers composed of anti-MXene borides (TMB) towards the nitrate reduction reaction (NO3RR) using density functional theory (DFT). The analysis reveals that these TMB monolayers emerge as promising candidates for electrochemical NO3RR, characterized by their exceptional stability, advantageous selectivity, and effective activation properties. Our study reveals that anti-MXene TMB monolayers, including MnB, RhB, CoB, IrB, OsB, and FeB, exhibit significant electrocatalytic potential for nitrate reduction, each with notable catalytic efficiencies demonstrated by their limiting potentials of −0.25 V, −0.29 V, −0.34 V, −0.36 V, −0.66 V, and −0.70 V, respectively. MnB shows a distinct preference for the NO3--to-N2 conversion pathway, whereas CoB, FeB, and OsB effectively facilitate both the NO3--to-NH3 and NO3--to-N2 pathways. Intriguingly, IrB and RhB primarily favor the NO3--to-NH3 pathway, highlighting their potential in ammonia synthesis applications. These variations in pathway preference not only underscore the diverse catalytic capabilities of these monolayers but also open new avenues for tailored catalytic applications and deepen our understanding of the mechanisms of nitrate reduction.