A Newly Predicted\nMagnetic TMB6 Monolayer for Efficient\nNitrogen Fixation

Developing electrocatalysts for the N<sub>2</sub> reduction\nreaction\n(NRR) with high activity, high selectivity, and low cost is urgently\nrequired to enhance the NH<sub>3</sub> yield rate. Based on first-principles\ncalculations, we predict a series of new transition metal boride TMB<sub>6</sub> (TM = Ti, V, Cr, Mn, Fe, and Co) monolayers and investigate\ntheir magnetoelectronic and electrocatalytic properties. The results\nreveal that VB<sub>6</sub> and CoB<sub>6</sub> favor ferromagnetic\ncoupling, while TiB<sub>6</sub>, CrB<sub>6</sub>, MnB<sub>6</sub>,\nand FeB<sub>6</sub> display antiferromagnetic ordering. Furthermore,\nTiB<sub>6</sub> exhibits a high Néel temperature of 344 K and\na large magnetic anisotropy energy of 614 μeV per Ti atom. Most\ninterestingly, TiB<sub>6</sub> and VB<sub>6</sub> exhibit superior\nNRR catalytic activity with a limiting potential of −0.50 and\n−0.19 V, respectively, and favorable NRR selectivity over the\nHER. Finally, the structural stability of TMB<sub>6</sub> monolayers\nhas been confirmed by a set of phonon dispersion, molecular dynamics,\nand elastic constant calculations. Our results highlight the use of\nthe newly designed two-dimensional (2D) TM borides as promising candidates\nfor spintronic devices and nitrogen fixation applications.