Nano zno

The waste rice noodle (WRN, main organic constituent: starch 21.36 g/100 g; protein 1.91 g/100 g; fat 0.4 g/100 g) was collected from the canteen of the Guilin University of Technology in Guilin, China. The nano ZnO (99.9% purity), methylene blue (98.5% purity), malachite green (98% purity), methyl violet (98% purity), basic fuchsin (98% purity), rhodamine B (98% purity), aniline (99.9% purity), tetracycline hydrochloride (98% purity), ethylenediaminetetraacetic acid disodium salt (EDTA–2Na, 98% purity), 2-propanol (IPA, 99% purity), 1,4-benzoquinone (BQ, 98% purity) and dimethyl pyridine N-oxide (DMPO, 99% purity) were all purchased from Macklin Reagent (Shanghai, China) without further purification.

The processes of the separators modification are shown in Fig. 2. Nano ZnO (99.9%, 30 ± 10 nm) and commercial β-MnO₂ (denoted as MnO₂) were purchased from MACKLIN. The solution of deionized water and ethanol in a volume ratio of 1 : 1 was prepared. ZnO, KB and polytetrafluoroethylene emulsion (PTFE) were added to the solution, in which the mass ratio of ZnO, KB and PTFE were 8 : 1 : 1; 7 : 2 : 1; 6 : 3 : 1; 5 : 4 : 1, and sonicated 4 h. The mixture was sprayed uniformly on one side of the commercial separators (Whatman GF/A) by an airbrush while the separator was heated on a heating plate. After drying, the separators were heated at 350 °C for 2 h to activate the PTFE. Finally, the separators were cut into discs with a diameter of 12.7 mm. The thickness of ZnO and KB modified layer on the separator after spraying was about 112.5 μm, as shown in Fig. S2.† MnO₂, acetylene black and PTFE were mixed in the same way, sprayed on the carbon paper and then activated to prepare the cathode electrode.