RESUMO
Electrochromic smart windows have attracted great attention due to their dynamic regulation of the solar spectrum. NiO and MnO2 are typical anodic coloration materials and widely investigated as complementary electrodes with WO3. However, NiO and MnO2 films often cannot be bleached to complete transparency, resulting in low transmittances and low optical modulations in the short-wavelength visible region. Herein, we report a porous nickel manganese layered double hydroxide (NiMn-LDH) nanosheet film directly grown on fluorine-doped tin oxide (FTO) glass using a one-step hydrothermal method, which demonstrates a high transmittance of 80.1% at 550 nm (without deduction of FTO glass). Induced by the double-redox couples of Ni2+/Ni3+ and Mn3+/Mn4+ associated synergistic electrochromic effect, the as-grown NiMn-LDH film electrode exhibits a large optical modulation of 68.5% at 550 nm, and a large solar irradiation modulation of 59.0% in the visible region of 400-800 nm. After annealing at 450 °C for 2 h, the NiMn-LDH film can be transformed into Ni6MnO8 film with a reduced optical modulation of 30.0% at 550 nm. Furthermore, the NiMn-LDH film electrode delivers an areal capacitance of 30.8 mF cm-2 at a current density of 0.1 mA cm-2. These results suggest that the as-prepared NiMn-LDH film electrode is a promising candidate for both electrochromic and energy storage applications.
RESUMO
Electrochromic smart windows are promising for building energy savings due to their dynamic regulation of the solar spectrum. Restricted by materials or traditional complementary device configuration, precisely and independently controlling of visible (VIS) and near-infrared (NIR) light is still on the drawing board. Herein, a novel Zn2+ electrochemically active Ce4W9O33 electrode is reported, which demonstrates three distinct states, including VIS and NIR transparent "bright and warm" state, VIS and NIR opaque "dark and cool" state, VIS transparent and NIR opaque "bright and cool" state. A dual-operation mode electrochromic platform is also presented by integrating Ce4W9O33/NiO complementary device and Zn anode-based electrochromic device (Ce4W9O33/Zn/NiO device). Such a platform enables an added VIS opaque and NIR transparent "dark and warm" state, thus realizing four color states through individually controlling Ce4W9O33 and NiO electrodes, respectively. These results present an effective approach for facilitating electrochromic windows more intelligent to weather/season conditions and personal preferences.