Electrochromic Thin Films Based on NiAl Layered Double Hydroxide Nanoclusters for Smart Windows and Low-Power Displays

Abstract

To develop electrochromic thin films for smart windows and low-power displays, homogeneous thin films were produced by spin coating colloidal NiAl layered double hydroxide (LDH) nanocluster solutions on a fluorine-doped tin oxide (FTO) glass substrate. The nano-LDH dispersion was synthesized via a facile one-step epoxide mediated process at room temperature. In situ relative transmittance measurements at 400 nm, recorded during potential scans in cyclic voltammetry or differential pulse chronoamperometry, showed the electrochromic behavior of the homogeneous thin films. The impact of various parameters on the electrochromic properties of the films was detailed, such as the thickness of the film, the nature of the electrolyte, and the presence of electroactive anions. The electrochromic properties, namely, the change in transmittance (ΔT) and the bleaching reversibility, were greatly improved using alkaline metal hydroxide as the electrolyte and in the presence of Fe(CN) 6 4−. The performances that we reached from the deposition of nanoclusters can be advantageously compared to the literature with ΔT = 70% and fast and good reversibility. Upon calcination, the NiAl-LDH film converted into mixed oxides (NiO and NiAl 2 O 4). The higher the calcination temperature, the lower was the ΔT value. The presence of porosity within the thin films, through the introduction of sacrificial polymeric beads and then decomposition at 400°C, was investigated, highlighting an enhancement of the ΔT value attributed to better accessibility to the nickel redox sites.

High performance NiOx nanoplatelet based films by a scrape-coating method for bifunctional electrochromic and energy storage devices

“…On the other hand, as the amount of PEG4000 added increases, the stronger the peaks at around 2930 and 2970 cm −1 , which can be attributed to the stretching vibration of the hydrocarbon bond (–CH) of the saturated carbon in PEG. 47 The intensity and width of the peaks for the NiO x -0.50 film are significantly larger than those of the NiO x -0.25 film, indicating a higher residual amount of PEG4000 in the former. In contrast, only very faint peaks are observed in the NiO x -0.05 film.…”

“…Therefore, excessive OH-groups on the (111) facets of the NiO x NPs would inevitably lower EC performance. On the other hand, as the amount of added PEG4000 increases, the stronger the peaks at around 2930 and 2970 cm -1 , which can be attributed to the stretching vibration of the hydrocarbon bond (-CH) of the saturated carbon in PEG 47 . the intensity and width of the peaks for the NiO x -0.50 film are significantly larger than those of the NiO x -0.25 film, indicating a higher residual amount of PEG4000 in the former.…”

Zn-Cr Layered Double Hydroxides for Photocatalytic Transformation of CO2 under Visible Light Irradiation: The Effect of the Metal Ratio and Interlayer Anion

“…The crystallite size (D, nm), basal space (d 003 -value, nm), cation-cation distance in the brucitelike layer (a, nm) and the variable related to three times the distance between adjacent brucite-like layers (c, nm) were parameters calculated and reported in Table 2. The value d 003 in LDHs with chloride as interlayer anion was 0.79 nm [61,62], whereas for GQDs, SDS and SDC, it was 1.21 nm [63], 2.60 nm [64] and 3.27 nm [65], respectively (Figure 3). Likewise, the c parameter shifted to higher values in LDH3-GQD, LDH3-SDS and LDH3-SDC with respect to LDH3-Cl.…”

Nickel Hydroxides: Requirements, Targeted Construction and Choice of Characteristics and Industrially Applicable Synthesis for Targeted Use in Electrochemical Devices

“…In one of the states, an electrochromic substance (oxidized or reduced) should be transparent, in the other state, it should be colored. Nickel oxide, [191][192][193][194] nickel hydroxide, [195] and Ni-based LDH (NiÀ Al LDH [196] ) are well-known electrochromic substances. In the reduced state (Ni(OH) 2 ), the substance has a very light green color and is almost transparent, while in the oxidized state (NiOOH), it has a dark brown color.…”