Hydrazine n2h4

Pd–B nanoparticles^{31 (link)} were prepared via the rapid chemical reduction reaction between palladium chloride (PdCl₂, Sigma-Aldrich) and sodium borohydride (NaBH₄, Sigma-Aldrich). PdCl₂ (89 mg) was dissolved in 2.5 mL deionized (DI) water. The B dopant concentration was controlled by dissolving NaBH₄ in 12.5 mL DI water (62.5, 250, 500, 1000 mg). NaBH₄ solution was placed in PdCl₂ solution. After the reaction between PdCl₂ and NaBH₄, the Pd–B nanoparticles were washed using DI water. After centrifuging, Pd–B nanoparticles were dried in a vacuum oven overnight. Pure Pd nanoparticles were prepared using hydrazine (N₂H₄, Sigma-Aldrich) as a reducing agent for PdCl₂ instead of NaBH₄.

We synthesized tellurene using a hydrothermal method as explained below. First, 4.4 mmol of PVP (Sigma Aldrich, St. Louis, MO, USA) was fully dissolved in 50 mL deionized water. PVP of different molecular weights (M.W. 58,000 or 360,000 g/mol) were incorporated, following the addition of 0.45 mmol of sodium tellurite (Na₂TeO₃, Sigma Aldrich, 99%) to the solution. As the components fully dissolved, the solution became transparent. Hydrazine (N₂H₄, Sigma Aldrich, 98%) and ammonium hydroxide solution (NH₄OH, 28% NH₃, Sigma Aldrich) were added as the reducing agent and pH adjustment, respectively. The dissolved solution was maintained for 10 min. The resulting solution was transferred to a Teflon-lined autoclave and heated at 180 °C for 30 h. After the reaction was completed, the Teflon-lined autoclave was left to cool down to room temperature. The obtained tellurene solution was washed four times with deionized water by centrifugation, and then the cleaned solution was dispersed in ethyl alcohol (Samchun Chemical Ltd., 99%, Seoul, South Korea).

To synthesize copper nanowires, a reagent, copper precursor, a capping agent, and a reducing agent are required. Sodium hydroxide (NaOH) was employed as a reagent to decompose copper precursors at the beginning of the procedure. Copper chloride (CuCl₂) was utilized as a copper precursor. Ethylenediamine (EDA, C₂H₈N₂, 99.5%, Sigma-Aldrich, Burlington, MA, USA) and hydrazine (N₂H₄, 35 wt % in H₂O, Sigma-Aldrich, Burlington, MA, USA) were used as a capping agent and a reducing agent, respectively. To fabricate Cu-Ag nanowires, silver nitrate (AgNO₃) was consumed as aa shell material to coat on the surface of copper nanowires, and methylsulfonylmethane (DMSO₂, >99.8%, Bergstrom Nutrition, Vancouver, WA, USA) was used as a copper surfactant and a silver reducing agent. Deionized water (DI H₂O) was used as a solvent to dissolve NaOH, CuCl₂, AgNO₃, and DMSO₂ and to dilute N₂H₄.