Potassium permanganate

Natural graphite powder (200 mesh, 99.9% purity), cupric chloride, concentrated sulphuric acid (98%), potassium permanganate, hydrogen peroxide (30%), hydrochloric acid, hydrazine hydrate (80%) and ammonia solution (30%) were purchased from Nanjing Chemical Reagent Co., Ltd. (Nanjing, China). L-Ascorbic acid (L-AA) was purchased from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China). All chemicals were of analytical grade and used as received without further purification. Deionized water was prepared in a Milli-Q Plus system (Millipore, Milford, MA, USA).

Bamboo powder was used as the source for the preparation of cellulose and was purchased from Zhejiang Lishui, China. Graphite powder (40 μm), used as the source for GO, was obtained from Qingdao Henglide Graphite Co., Ltd. Poly(vinyl alcohol) (PVA, M_w ≈ 95,000 g/mol), glutaraldehyde (GA, crosslinker, 25 wt % in H₂O), potassium hydroxide (KOH), Sudan III, acetic acid (CH₃COOH), hydrogen peroxide (H₂O₂, 30%), potassium permanganate (KMnO₄), concentrated sulfuric acid (H₂SO₄, 98%), hydrochloric acid (HCl), sodium nitrate (NaNO₃), sodium chlorite (NaClO₂), phosphorus pentoxide (P₂O₅), potassium persulfate (K₂S₂O₈) and ammonium hydroxide (NH₃·H₂O) were purchased from Nanjing Chemical Reagent Co., Ltd. These materials were all used without further purification.