H3po4

All chemical reagents were of analytical grade, used as supplied without further purification unless indicated. Pyrrole, KH₂PO₄, H₃PO4, lysozyme, sodium dodecyl sulfate (SDS), and NaOH were purchased from Wako Pure Chemical Industries (Japan). Nutrient broth was purchased from Eiken Chemical (Japan). Bacterial viability kit L7007 (SYTO9/PI) was purchased from Molecular Probes. Bacteria such as E. coli O157:H7 and E. coli O26:H11 were provided by Prof. Miyake in Osaka Prefecture University. On the other hand, Salmonella enterica, Vibrio parahaemolyticus, Staphylococcus aureus, and Bacillus subtilis were purchased from the Biological Resource Center (NBRC), National Institute of Technology and Evaluation, Japan. Milli-Q grade (>18 MΩ) water with ultraviolet sterilization was used throughout the study.

GO material was prepared by improved Hummers methods^{6 (link),38 (link)} with natural graphite of Bay carbon graphite from Michigan. The graphite powder (5 g) was inserted in the mixture of 200 mL H₂SO₄ (96%, Wako Chemical Co. Ltd.) and 25 mL H₃PO₄ (85% Wako Chemical Co. Ltd.) followed by addition of 25 g KMnO₄ powder (Wako Chemical Co. Ltd.). The mixing of the chemicals with exothermic reactions was carried out very slowly under cooling with ice-water bath to control the temperature at 311 ± 2 K stirring at 200 rpm for 2 h. Then, the 500 mL of distilled water was added slowly into the mixture followed by addition of 100 mL H₂O₂ solution (10%, Wako Chemical Co. Ltd.). Then, the supernatant by centrifugation was collected and was washed with 1 M HCl (Wako Chemical Co. Ltd.) at 3 times and then washed with distilled water to reach the pH of the washed liquid to 7. Finally, we obtained GO powders by freeze-drying of the GO suspension with liquid nitrogen.

LiCoPO₄ materials were directly synthesized by one-pot supercritical fluid method with a reaction time of 6 min. Typically, 2 mmol cobalt acetate tetrahydrate (Co(Ac)₂.4H₂O, Wako, Japan) and 2 mmol lithium acetylacetonate (LiAcac, Wako, Japan) was dissolved in 15 ml ethanol and the solution was heated at 60°C with continuous stirring. The solid salts was completely dissolved within 1 min, followed by addition of solution of phosphoric acid (H₃PO₄, aqueous solution, 85%, Wako, Japan) in 4 ml ethanol. The molar ratio of Co(Ac)₂:LiAcac:H₃PO₄ is of 1:1:1. Hexamethylenetetraamine (HMT) or hexamethylenediamine (HMD) were used as in situ OH⁻ sources and structure-directing agent to control the growth rate as well as morphology of LiCoPO₄. The obtained blue suspension was heated with continuous stirring at 60°C for 10 munities then 5 ml each solution was transfer to a batch reactor (10 ml, 4 reactor) and heated at 400°C and 38 MPa pressure for 6 minutes. After which reactors were allowed to cool to room temperature by water quenching. The resultant powder was separated by centrifugation and washed with distilled water and ethanol until the pH of the solution became neutral. Finally, the obtained specimen was dried at 60°C for 1 day. The above synthesis condition has been optimized to obtain the LiCoPO₄ particles with good homogeneity and superior cathode performance.

All raw chemicals were reagent grade and were used without purification, and distilled water was used in all experiments. Graphite, Na₂WO₄·2H₂O, CsCl, and methanol were purchased from Sigma Aldrich Chemistry. NaNO₃, H₂SO₄, HCl, H₃PO₄, and KCl were purchased from Fuji Film Wako Pure Chemical Corporation. KMnO₄ and H₂O₂ were purchased from the Tokyo Chemical Industry.