Facile synthesis of oxygen-deficient MoO3-x nanosheets by light radiation for fast electrochromic supercapacitors

•Light radiation method was used to fast (< 2 min) and large-scale in situ synthesis α-MoO3-x nanosheets.•The prepared α-MoO3-x nanosheets have unique layered structure and trace oxygen vacancy.•Ultra-fast-switching electrochromic supercapacitor was achieved with the α-MoO3-x nanosheets.•The conductivity of single α-MoO3-x nanosheet was enhanced by one orders of magnitude compared to MoO3 nanobelt.•Single α-MoO3-x nanosheet exhibits a linear dependence between electrical conductivity and temperature. Electrochromic supercapacitors are versatile devices that can visually direct stored energy status in real time through color change. It is promising but challenging for transition metal oxides to achieve high energy density and fast response simultaneously by using feasible materials and simple preparation method due to their low electrical conductivity and ordinary reaction kinetics. Herein, we demonstrate a facile and efficient light-radiation method for rapid (< 2 min) and large-scale preparation of oxygen-deficient α-MoO3-x nanosheets with high electrochromic and supercapacitive performances. The large optical contrast of 40.2% at 650 nm, ultra-fast coloring and bleaching response time (3.2 s and 0.9 s), good coloration efficiency (30.4 cm2 C-1) and high specific capacitance (80 F g-1) are achieved by utilizing these α-MoO3-x nanosheets as electrochemical active materials. With remarkable electrochromic and energy-storage properties, the α-MoO3-x nanosheets prepared by the facial light radiation method show great potential applications in large-area intelligent multifunctional supercapacitors for information technology, electric vehicles, aerospace and defense technology. Oxygen-deficient α-MoO3 nanosheets, prepared by a facial light irradiation method within 2 min, successfully combines good electrochromic and supercapacitive properties simultaneously. [Display omitted]