Nickel sulfate hexahydrate

All chemical reagents used in this work were of analytical grade (AR) and used without further purification. Polyacrylonitrile (PAN, Mw = 90,000) were purchased from J&K Scientific, Ltd. (Beijing, China) 3,4-ethylenedioxythiophene, sodium borohydride, and polystyrene sulfonate (PSS, Mw = 80,000) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Sodium hydroxide, ammonium chloride, nickel sulfate hexahydrate, sodium citrate, sodium hypophosphite, ferric chloride, ethanol, N,N-dimethylformamide, and trichloromethane were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

All reagents used in experiments were of analytical grade. Graphite powder was purchased from Alfa Aesar (Shanghai, China). Nickel sulfate hexahydrate, iron sulfate heptahydrate, hydrazine hydrate (80 wt%), and glucose were procured from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Ascorbic acid (AA), uric acid (UA), and dopamine (DA) were purchased from Acros (Shanghai, China). Deionized water (18.2 MΩ·cm) was used in all experiments.

Nickel sulfate hexahydrate (NiSO₄∙6H₂O), sodium hydroxide, 85% hydrazine hydrate (N₂H₄∙H₂O) and N,N-dimethylformamide (DMF) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). All reagents were of analytical grade and used without further purification. Multi-walled carbon nanotubes (MWCNTs, NC7000) were purchased from Nanocyl (Sambreville, Belgium), with an average diameter of 9 nm and a length of about 1.5 μm. The polyvinylidene fluoride 6020 (MRF: 2 g/10 min, 230 °C/21.6 kg) was provided by Solvay (Brussels, Belgium) and the CO₂ gas (purity: 99.5%) supplied by DaTong gas Co., Ltd. (Chengdu, China).