For the Ni (II) complex, the band energy differences are consistently negative, ranging from -0.755 eV to -1.002 eV. This indicates a strong tendency for electron transfer, as negative values suggest the complex possesses lower unoccupied molecular orbitals (LUMOs) that are readily accessible for proton reduction. Such energetics are conducive to efficient catalytic behavior in HER, as the energy gaps align well with the thermodynamic and kinetic requirements for hydrogen generation.