Thiourea

The materials and reagents are as follows: 2-Methylimidazole (99%, J&K, Beijing, China), thiourea (99%, J&K, Beijing, China), potassium bromide (99%, J&K, Beijing, China), zinc dihydrate acetate (99%, J&K, Beijing, China), sodium sulfate (99%, J&K, Beijing, China), disodium ethylenediaminetetraacetic acid (EDTA) (99%, J&K, Beijing, China), benzoquinone (99%, J&K, Beijing, China), methanol (≥99.7%, J&K, Beijing, China), isopropanol (99.5%, J&K, Beijing, China), Rhodamine B (96%, J&K, Beijing, China), anhydrous ethanol (≥99.7%, Fuyu chemical, Tianjin, China), cobalt nitrate hexahydrate (98%, Damao chemical reagent factory, Tianjin, China), and cadmium acetate dihydrate (99%, Thermo Fisher Scientific, Waltham, MA, USA). The ITO slides are purchased from Luoyang Guluo Glas Co., Ltd. (Luoyang, China).

Triethylammonium nitrate ([Et₃NH]NO₃, 98%) was purchased from the Centre for Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences. Polyethylene glycol (PEG-200, 99%), thiourea (99%), molybdenum disulfide (99%), and copper oxide (CuO, 97%) were supplied by J&K Scientific Co., Ltd. Tungsten sulphide (99%) was purchased from Adamas Reagent Co., Ltd. Copper nitrate trihydrate (99%), lead acetate trihydrate (99%) and zinc nitrate hexahydrate (99%) were obtained from Sinopharm Chemical Reagent Co., Ltd. Nafion D-521 dispersion (5% w/w in water and 1-propanol, ≥0.92 meg per g exchange capacity), Nafion N-117 membranes (0.180 mm thick, ≥0.90 meg per g exchange capacity), copper sulfide (99.8%), cadmium sulphide (98%) and Toray carbon paper (CP, TGP-H-60, 19 × 19 cm) were purchased from Alfa Aesar China Co., Ltd.

Ionic liquids, including 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF₄, >99%), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄, >99%), 1-octyl-3-methylimidazolium tetrafluoroborate ([Omim]BF₄, >99%), and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim]BF₄, >99%) were purchased from the Centre of Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences. Polyethylene glycol (PEG-200, >99%), thiourea (>99%), lead(ii) acetate trihydrate (>99%), tetrabutylammonium tetrafluoroborate ([TBA]BF₄, >99%), and tetrabutylphosphonium tetrafluoroborate ([TPA]BF₄, >99%) were supplied by J&K Scientific Co., Ltd. Nafion D-521 dispersion (5% w/w in water and 1-propanol, ≥0.92 meg g^–1 exchange capacity), Nafion N-117 membrane (0.180 mm thick, ≥0.90 meg g^–1 exchange capacity), and Toray Carbon Paper (CP, TGP-H-60, 19 × 19 cm) were purchased from Alfa Aesar China Co., Ltd.