Figure 4
From: Synthesis of 2D layered transition metal (Ni, Co) hydroxides via edge-on condensation
Optical and electrical characterizations of Ni(OH)2. (A) Optical absorption spectrum of few layers α-Ni(OH)2 thin flakes on ITO glass, measured by UV–Vis from 300 to 700 nm. (B) Tauc plot derived from (A), the extrapolated bandgaps are 2.54 eV and 3.51 eV, corresponding to few layers and bulk α-Ni(OH)2, respectively. (C) Bandgap extrapolated from reflected electrons energy loss spectroscopy (REELS) by measuring the gap between the center of elastic scattering peak and the cutoff of the low energy loss peak is 2.52 eV. (D) Schematic of Au-Ni(OH)2-Ti sandwich-like device. The top Ti electrode is grounded and voltage is applied on the bottom Au electrode for all measurements. (E) Typical I-V characteristics of samples with different thicknesses, from 4.9 to 18.3 nm. Current increases exponentially under positive bias on all four measured samples. Inset: optical image of the device. (F) Current density–electric field strength correlation of the tested samples with current in logarithm scale. The thinnest sample, 4.9 nm, exhibits the highest breakdown field, 4.47 MV/cm.
