Enhancement of the hydrogen evolution reaction of MA2Z4 monolayer family by vacancy and bimetallic doping: First-principles calculations

Hydrogen as a sustainable and clean energy source has been widely noticed, but it is urgent to find an efficient and stable electrocatalyst to increase its hydrogen production. For the catalytic performance of electrocatalysts, defects, doping, and stress are usually selected to enhance the catalytic performance, on the basis of which in this paper, MSi2N4 (M = Mo, W) system containing vacancies and bimetallic doping was constructed and analyzed for its HER performance. The results show that the formation energy of all structures is stable and Ni doping can significantly improve the stability according to formation energy of the structures with vacancy. Both ipsilateral doping and contralateral doping can significantly improve the Gibbs free energy of MA2Z4 materials, especially the MoSi2N4 doped with double Co. In particular, the values of Gibbs free energy of C-Ni-VN@MoSi2N4-Nin and C-Co-VN@WSi2N4-Nin are −0.027 eV and 0.041 eV, significantly better than the performance of the recognized electrocatalyst Pt, which has a free energy of only 0.09 eV. After doped with transition metallic atoms, the energy bands of all materials present semiconductor property. Our work provides a novel method for the regulation of MA2Z4 family materials and a theoretical strategy for designing efficient HER electrocatalysts.