Tuning electronic structure promoted the hydrogen evolution reaction activity of defective MSi2N4 (M=Mo, W) by transition metal and non-metal doping

Hydrogen is an important candidate for the next generation of clean energy among the studied green energy. However, H2 production efficiency is still low due to lack of efficient catalysts. Herein, the hydrogen evolution reaction (HER) performances of MSi2N4 (M = Mo, W) and N (Si) defective structures with single transition metal (TM = Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Ru, Pd, Ag, Ta, W, and Ir) and nonmetal (NM=B, O, P, and S) atoms doping are investigated by first principles calculations. The results show that N and Si vacancies promote HER activity of pristine MoSi2N4 and WSi2N4, and N vacancy delivers relative higher HER activity than that of Si vacancy. Interestingly, the HER performance of MoSi2N4 and WSi2N4 can be further improved by tuning their electronic structure with NM and TM doping. O/MoSi2 Nv4 and O/WSi2 Nv4 deliver optimal Delta GH* values (Delta GH* = -0.09 eV and -0.21 eV, respectively) among the NM doped structures. Four of TM doped structures, Co/Mo Siv2 N4, Co/W Siv 2 N4, Pd/Mo Siv 2 N4, and Pd/W Siv 2 N4 deliver near-zero Delta GH*values, with the corresponding Delta GH*of -0.05, -0.01, 0.02, and 0.06 eV, respectively. More works suggest that there is a strong linear relationship between Delta GH*and descriptor jr (related with valence-electron number and electronegativity), with the correlation coefficient R2 are 0.91 and 0.76 for TM/Mo Siv 2 N4 and TM/W Siv 2 N4, respectively, suggesting that jr is a good descriptor for screening HER catalysts for TM doped M Siv 2 N4, especially for TM/Mo Siv 2 N4 structures. In addition, the jr-log (i0) volcano curve indicates that when the jr is about 9.15 eV (peak points), the TM doped structures obtained optimal HER activity.