  Two-dimensional (2D) boron monolayers have been successfully synthesized on
silver substrate very recently. Their potential application is thus of great
significance. In this work, we explore the possibility of boron monolayers
(BMs) as electrocatalysts for hydrogen evolution reaction (HER) by
first-principle method. Our calculations show that the BMs are active catalysts
for HER with nearly zero free energy of hydrogen adsorption, metallic
conductivity and plenty of active sites in the basal plane. The effect of the
substrate on the HER activity is further assessed. It is found that the
substrate has a positive effect on the HER performance caused by the
competitive effect of mismatch strain and charge transfer. The indepth
understanding of the structure dependent HER activity is also provided.
