Potassium borohydride

The chemicals and reagents were bought from domestic or foreign vendors, and they were used directly after purchase without any further processing. The materials included ferric nitrate—nonahydrate (Fe(NO₃)₃⋅9H₂O, 98%, SD Fine Chem. LTD), sodium hydroxide pellets (97%, ACROS Organics), glacial acetic acid (98%, CARLO ERBA chemicals), acetyl acetone (98%, LOBA Chemie), formaldehyde (37%, ROTH) and nitrogen-doped titanium dioxide (Company, China). Methanol (99.8%), titanium dioxide (99%), sodium chloride (98.5%), hydrochloric acid (37%), ammonium acetate (99.99%), potassium borohydride (98%) and polyvinyl pyrrolidone (PVP, 55.000 g/mol) were supplied from Sigma-Aldrich.

Lead (II), telluride (TeO₂, 99.998% trace metals basis), potassium hydroxide (KOH), trisodium-citrate (TSC) and potassium borohydride (KBH₄) were purchased from Sigma Aldrich (St. Louis, MO, USA). Lead Nitrate (Pb(NO₃)₂, 99% pure) was obtained from Fisher Scientific (Pittsburgh, PA, USA). All the materials were pure and used as received. Additional purification was not done, when analytical grade precursors were utilized. Double distilled deionized water was used.

Commercial organic solvents (toluene ≥ 99.5%, diethyl ether ≥ 99.7%, dichloromethane ≥ 99.8%) were purchased from Sigma Aldrich (Germany) and purified with Na/benzophenone (toluene, diethyl ether) or CaH₂ (dichloromethane) following literature methods [44 ]. 1H-benzotriazole (≥ 99.0%) and potassium borohydride (98%) were Sigma Aldrich (Germany) products, used as received. Yttrium and lanthanide chlorides (99.9% in all the cases) were Strem Chemicals (France) products, used without further purifications. Poly(methyl methacrylate) (PMMA, M_w = 86,000 g mol⁻¹) was purchased from TCI Chemicals (Belgium) and used as received. Potassium tris(benzotryazol-1-yl)borate, K[tbtz], was synthesized accordingly to literature procedures [45 (link)–47 (link)].