Fig. 5: Electronic characterization and band structure of Ni-BAND.

a Tauc plot from UV-Vis spectrum of Ni-BAND showing optical band gap, where α is absorption coefficient h is the Planck constant, ν is the photon’s frequency, and E_g is the band gap energy. Linear background fit parameters: slope, 37.4; y-intercept, −34.1. Linera peak fit parameters: slope, 506; y-intercept, −634. b UPS spectrum near the Fermi level, where E_v is the energy difference between the valence band maximum and the Fermi level. Linear fit parameters: slope, 2.01 × 10⁵; y-intercept, −2.34 × 10⁵. c Arrhenius plot of electrical conductivities (σ) measured using four-point-probe measurement, where T is the measured temperature. Linear fit parameters: slope, −0.6765; y-intercept, 0.7588. d Optimized crystal structure of Ni-BAND in real space and its corresponding first Brillouin zone in reciprocal space. Fractional coordinates of all atoms are provided in Supplementary Data 2, and coordinates of high-symmetric points in the reciprocal space (Γ, Χ, Υ, Z, R, T, U, V, P and P’) are provided in Supplementary Table 7. Calculated electronic band structure (top) and density of states (bottom) for pristine (e) and NO₃⁻ removed, n-doped Ni-BAND (f). g Schematic representation and density of states upon n-doping. Source data are provided as a Source Data file.