Room-Temperature Liquid-Phase Exfoliation of MoO3 Nanosheets for Photochromic Smart Windows

Abstract

Photochromic smart windows represent a promising technology for reducing building energy consumption, owing to their broad spectral tunability, high optical transmittance (Tlum), superior solar regulation efficiency (ΔTsol), and passive response. A major limitation currently stalling the progress of photochromic smart windows is the reliance on tungsten oxides, which suffer from slow bleaching rates and often irreversible behavior. In this work, we propose MoO3 nanosheets as an alternative photochromic material for smart windows. Such MoO3 nanosheets was fabricated by a facile room-temperature liquid-phase exfoliation method from the commercial MoO3 powder. It exhibits pronounced and reversible photochromism, a stark contrast to the photochromically inert commercial MoO3 powder. The MoO3 nanosheet-based film is transparent in the bleached state, with a Tlum of 85.82%. It achieves a ΔTsol of 36.39% by strongly blocking 500-1500 nm light (centered at 820 nm) after UV coloration. This performance originates from the generation of molybdenum bronze, whose localized surface plasmon resonance (LSPR) from extra electrons is distinctly enhanced by the nanosheets' confined geometry, giving rise to the intense Vis-NIR absorption. Therefore, this work opens up new possibilities for the research of photochromic smart windows.