Preparation of VO2@SiO2 @TiO2 nanoparticles. First, the as-prepared VO2@SiO2 nanoparticles were dispersed in an ethanol solution under strong stirring for 30 min. Then , the required amount of tetrabutyl titanate(TBOT) was quickly added . Finally, an ethanol solution containing 0.03 mL of NH3?H2O was added drop-wise to the solution over 5 min. The reaction was maintained at 45 u C for 24 h. When the reaction was complete, the sample was collected by centrifugation, washed with deionised water and ethanol several times, and dried at 50uC for 6 h31. Please see the reference for further information on the preparation of VO2 nano- particles and VO2@SiO2 nanoparticles 19.