Fig. 5: Theoretical calculations of n-Cu/BP on HER.

a Total and partial DOS of Cu, Co, Fe, Ni, and Mo single atoms on BP support. b The adsorption energy values of the common transition metal single-atom models. c The theoretically calculated charge transfer values for metal single atoms on BP as a function of the ICOHP values. d Calculated free energy diagram of the HER with M-P3 as an active center. e The charge density difference diagram of Cu/BP and corresponding charge transfer from the Cu atom to the BP layer. Cyan and yellow contours represent electron depletion and accumulation. The isosurface value is 0.002 e/Å3. f Free energy of water dissociation diagram for n-Cu/BP, n-Co/BP and CuCo/BP.