Activating electrocatalytic hydrogen evolution performance of two-dimensional MSi2N4(M = Mo, W): A theoretical prediction

Very recently, a type of two-dimensional (2D) crystals, MSi2N4(M = Mo, W), has been successfully synthesized in experiment [Y.-L. Hong et al., Science 369, 670 (2020)]. Here, using first-principles calculations, we systematically investigate the potential of two-dimensional (2D) MSi2N4 as hydrogen evolution reaction (HER) catalysts, and propose two effective ways to trigger their HER activity. Our computations reveal that while the metal vacancies cannot activate the inertia planes for HER, 2D MSi2N4 with N vacancy exhibits excellent HER performance. Especially for 2D WSi2N4, the introduction of N vacancy can yield an ideal value of hydrogen adsorption Gibbs free energy (Delta G(H*) = - 0.02 eV), even superior to that of Pt (Delta G(H*) = - 0.09 eV). Moreover, by high-throughput screening of 3d, 4d, and 5d transition metals, we find that introducing V/Fe/Nb/Tc/Ta atom into 2D MSi2N4 can significantly trigger their HER activity. The underlying physics are discussed in detail. Our work not only highlights a family of potential HER electrocatalysts, but also provides feasible strategies for triggering their HER activity.

Automated summary

The study found that introducing N vacancies in 2D MSi2N4 can significantly enhance its hydrogen evolution reaction catalytic activity, especially in 2D WSi2N4, N vacancies can yield a hydrogen adsorption Gibbs free energy superior to that of Pt. By introducing specific atoms, the HER activity of 2D MSi2N4 can be significantly triggered, providing new insights for designing more efficient HER catalysts.