2. Experimental Section
2.1 Materials
All chemicals can be used directly without any further purification any more. Al nanoparticles (Al NPs) (~100nm diameter) are purchased from Shanghai Nai-ou Nano Technology Co., LTD, and the thickness of alumina shell on the surface of Al NPs is about 5 nm, so the active aluminum content is about 64.5%. Potassium hypermanganate (KMnO4) (>99.5%) and concentrated hydrochloric acid (HCl) (36.0%~38.0%) are supplied by Shanghai Lingfeng Chemical Reagent Co., LTD for further MnO2 synthesis. MnO2 nanorods (MnO2 NRs) are synthesized via hydrothermal method at 140 oC for 12 h, please see Ref.[26-27]. Poly(VDF- ter- HFP-ter - TFE) terpolymer is selected from Shanghai 3F New Chemical Materials Co., LTD, with about 67.5% fluorine content. As for solvents and dispersant, ethyl alcohol, deionized water and dimethylformamide (DMF) are purchased from Nanjing Chemical Reagent Co., LTD.
2.2 Sample Preparation
The ratio of each component is listed in Table 1. In a typical preparation experiment, the mixture of Al NPs and MnO2 NRs is dispersed in ethyl alcohol by using ultrasonic method. In the meanwhile, the corresponding poly(VDF- ter- HFP-ter - TFE) terpolymer component is dissolved by DMF. Then, the terpolymer -DMF solution is poured into the mixture of Al NPs and MnO2 NRs as the precursor for further electrospray method. The diagram of electrospray experiment is shown in Figure 1. The precursor is put into the syringe with a 0.43 mm flat nozzle. The distance between the end of nozzle and the receiving plate is about 10 cm, and there is a 14 kV DC voltage loaded onto the distance. The precursor is ejected by a syringe pump with the velocity of 4.0 mL h-1. During the process, the solvent volatilized and solid-state samples attach to the receiving plate. Finally, the samples are gently scraped off from the receiving plate for further tests.
Table 1 The detailed ratio of each component