Selenium powder

Niobium powder (99.9%), selenium powder, iodine (analytical grade) and n-butyl-lithium (n-BuLi; 2.5 M in hexane) were purchased from SinopharmChemical Reagent Co. Ltd. Hydrazine hydrate (98%) was purchased from Aladdin Chemical Reagent Co. Ltd. Bulk NbSe₂ was prepared following previously reported literature, which took advantage of the chemical vapour transport method with I₂ as the transport agent. In detail, 1 mmol Nb, 2 mmol Se and 100 mg I₂ powders were well mixed and sealed under vacuum (10⁻⁵ torr) inside a quartz tube, which is of 12 cm long and 0.8 cm inner diameter. The transport was achieved by establishing an 80°C gradient along the tube with the T_hot=900 °C, and the mixture was heated for 36 h.The resultant was gathered and grounded for the following procedure.

Bismuth neodecanote, oleic acid (90 %), cadmium oxide (99.99 %), bis(trimethylsilyl) sulfide ((TMS)₂S), hexadecylamine (90 %), tri-n-octylphosphine oxide (90 %), and trioctylphosphine (97 %) were purchased from Aldrich. Oleyl amine (90 %) was purchased from Aladdin. Thioacetamide and selenium powder were purchased from Sinopharm. 1,2-Dipalmitoyl-sn-glycero-3-phosphoethanol-amine-N-[methoxy(polyethylene glycol)-2000] (PEG-DSPE, 99 %) was purchased from Avanti. All chemicals were used as received, unless otherwise stated.

Polyacrylonitrile (PAN, Mw = 150,000 g mol⁻¹) was purchased from Sigma–Aldrich. Natural graphite powder (325 meshes) was obtained from Alfa-Aesar. Selenium powder (Se, 99.99%), Na₂MoO₄ (99.99%), hydrazine hydrate (N₂H₄·H₂O, 50 wt% in water), N,N-dimethylformamide (DMF), ethanol, 98% H₂SO₄, 30% H₂O₂, KMnO₄, NaNO₃, and 37% HCl were provided by Sinopharm Chemical Reagent Co. Ltd. All aqueous solutions were prepared with doubly distilled (DI) water.